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AUTUMN MEETING, SEPTEMBER 2008 EAST MIDLANDS

AUTUMN BRITISH VETERINARY DERMATOLOGY STUDY GROUP AUTUMN MEETING

13th and 14th SEPTEMBER 2008 EAST MIDLANDS AIRPORT THISTLE HOTEL

SPONSORS

Principal Sponsor:

VIRBAC

Major Sponsors:

DECHRA VETERINARY PRODUCTS

HILLS PET NUTRITION JANSSEN ANIMAL HEALTH

PFIZER

Main Sponsors:

ARTU BIOLOGICALS

BAYER

MERIAL ANIMAL HEALTH

NATIONWIDE VETERINARY LABORATORIES

NOVARTIS ANIMAL HEALTH

ROYAL CANIN

The B.V.D.S.G. committee and members would like to thank our sponsors for their generosity and support of this meeting Proceedings published for the British Veterinary Dermatology Study Group by Affiniti, Adventis Health Limited, Adventis House, Post Office Lane, Beaconsfield HP9 1FN Proceedings editor: Paul S Coward. Anthills, 25 Moneyfly Road, Verwood, Dorset BH31 6BL [email protected]

1 PROGRAMME

DISEASES OF THE FACE AND FEET

SATURDAY 13 TH September 2008

9.00 - 9.45am REGISTRATION

Morning session

9.45 - 10.15 Anatomy and Surgery of Foot and Claw Structures Prue Neath

10.15 - 10.45 Surgery of Foot and Claw Structures Prue Neath

10.45 - 11.30 COFFEE AND COMMERCIAL EXHIBITION

11.30 - 12.15 Lymphocytic-Plasmacytic Pododermatitis in the Dog Rory Breathnach

12.15 - 1.00 The Canine Foot as a Predilection Site for Disease Rory Breathnach

1.00 - 2.00 LUNCH

1.30 - 2.00 ESVD AGM

2.00 - 2.30 COFFEE AND COMMERCIAL EXHIBITION

Afternoon session

2.30 - 3.15 Symmetrical Lupoid Onychodystrophy Rory Breathnach

3.15 - 4.15 Uveodermatological Syndrome – an Ophthalmologist’s Approach Jim Carter

4.30 - 5.15 TEA AND COMMERCIAL EXHIBITION

5.15 - 6.00 BVDSG AGM

2 SUNDAY 14 TH September 2008

Morning session

9.00 - 9.45 Immune-Mediated Blistering Diseases Vanessa Schmidt

9.45 - 10.30 Facial Dermatoses in Domestic Animals; Cutaneous Lupus Erythematosus and Mucocutaneous Pyoderma Filippo De Bellis

10.30 - 11.15 COFFEE AND COMMERCIAL EXHIBITION

11.15 - 12.00 Common Infectious Diseases of the Feet in Sheep and Cattle Agnes Winter

12.00 - 12.45 Diseases of the Feet and Face in Sheep and Cattle Agnes Winter

1.00 - 2.00 LUNCH

2.00 - 2.30 COFFEE AND COMMERCIAL EXHIBITION

Afternoon session

2.30 - 3.15 Canine Claw Diseases and Research John Reilly

3.15 - 4.00 Anatomy and Common Diseases of the Equine Hoof John Reilly

Abstracts

4.00 - 4.15 0.4% dimeticone spray; a novel control material to kill fleas by physical means Jones I, Kidman ER, Burgess I.

3 CONTENTS

Page no. Anatomy and Surgery of Foot and Claw Structures 5 Prue Neath

Surgery of Foot and Claw Structures 6 Prue Neath

Lymphocytic-Plasmacytic Pododermatitis in the Dog 7 Rory Breathnach

The Canine Foot as a Predilection Site for Disease 11 Rory Breathnach

Symmetrical Lupoid Onychodystrophy 19 Rory Breathnach

Uveodermatological Syndrome – an Ophthalmologist’s Approach 21 Jim Carter

Immune-Mediated Blistering Diseases 27 Vanessa Schmidt

Facial Dermatoses in Domestic Animals; Cutaneous Lupus 35 Erythematosus and Mucocutaneous Pyoderma Filippo De Bellis

Common Infectious Diseases of the Feet in Sheep and Cattle 41 Agnes Winter

Diseases of the Feet and Face in Sheep and Cattle 45 Agnes Winter

Canine Claw Diseases and Research 48 John Reilly

Anatomy and Common Diseases of the Equine Hoof 49 John Reilly

0.4% dimeticone spray; a novel control material to kill fleas by 50 physical means Jones I, Kidman ER, Burgess I.

4 ANATOMY AND SURGERY OF FOOT AND CLAW STRUCTURES Prue Neath

Abstract not submitted NOTES

5 SURGERY OF FOOT AND CLAW STRUCTURES Prue Neath

Abstract not submitted NOTES

6 LYMPHOCYTIC-PLASMACYTIC PODODERMATITIS IN THE DOG Dr Rory Breathnach MVB MSc PhD MRCVS Lecturer in Dermatology and Internal Medicine

University College Dublin Faculty of Veterinary Medicine 4 Dublin IRELAND

Pododermatitis is a common and frequently debilitating inflammatory disease of the pedal skin of dogs. The clinical history is often characterised by periods of disease exacerbation and remission. While pododermatitis may represent simply one component or manifestation of an otherwise more extensive dermatological disease, some dogs have lesions confined solely to the foot.

IDIOPATHIC PODODERMATITIS Despite the large number of differential diagnoses for pododermatitis, the results of laboratory and other ancillary investigations in affected dogs frequently prove unrewarding. Animals that fall within this category are classified as having idiopathic pododermatitis (IP). Although poorly understood, various theories have been proposed to explain the underlying pathogenesis in idiopathic disease including pedal conformation, trauma, immunosuppression, bacterial infection and furunculosis with dermal granuloma formation. Bacterial infection has been reported to be a significant component of IP. However, bacterial infection invariably occurs secondary to other diseases such as hypersensitivity disorders or immunosuppression. Furthermore, pedal lesions that heal by second intention may be predisposed to mixed dermal infections involving opportunistic bacteria. It has been suggested that bacterial folliculitis may progress to furunculosis, with the subsequent release of follicular contents into the dermis and resultant granuloma formation. Thus, it is possible that bacterial infection and hair follicle- related pathology may contribute to the dynamism frequently encountered in IP dogs.

LYMPHOCYTIC-PLASMACYTIC PODODERMATITIS (LPP) A sub-population of IP dogs exists in which affected animals are systemically healthy but have persistent inflammation and pruritus confined to the pedal skin.

Clinical findings Males and females are usually equally represented. The mean age for onset of clinical signs is approximately 5 years. All four feet are affected in 80-90% of cases. Lesions are typically present on both the dorsal and palmoplantar skin surfaces. Lesions involving the pad surface are uncommon. There is no evidence of a seasonal component to the disorder or any consistent temporal association with specific therapeutic agents. The dominant clinical signs present are pruritus, erythema, alopecia and localized skin thickening. A web-like appearance to the foot is noted in 80% of cases. Pain/discomfort on palpation is common. Sinus tracts and haemorrhagic bullae occur in 25-40% of cases. Results of clinical pathology and diagnostic imaging investigations are typically normal i.e. most cases are systemically healthy.

Histopathology of lesional biopsies Lesional biopsies are characterised by the presence of a perivascular dermatitis reaction accompanied by dermal oedema, epidermal hyperplasia, hyperkeratosis and spongiosis. In all cases examined, the perivascular infiltrates are composed of moderate-to-marked numbers of lymphocytes and plasmacytes. Hyperkeratosis, when present, is usually classified as diffuse in distribution and moderate in severity. The pattern observed is invariably orthokeratotic. Epidermal hyperplasia is moderate- to-severe in more than 80% of cases. The stratum spinosum and stratum granulosum are the two sub-regions primarily affected by this change. Spongiosis is often moderate in severity and focal in distribution. Mild vacuolar degeneration within epidermal cells is seen in approximately 20% of cases with LPP. Mononuclear cell exocytosis is a prominent finding in the epidermis of 75% of cases, with focal epidermal erosion/ulceration observed in approximately 25% of

7 affected dogs. Mild-to-moderate disruption of the dermo-epidermal (D-E) junction is seen in 25% of dogs, with a similar incidence figure for melanin incontinence. Vasodilation of dermal blood vessels and superficial dermal oedema are prominent findings in virtually all dogs with LPP (however, a leucocytoclastic vasculitis reaction pattern is not a feature). The superficial and middle dermal blood vessel plexi are the predominant ones participating in the response observed. Perivascular aggregates are usually most pronounced in the superficial and mid-dermis. However, lymphocyte and plasma cell infiltrates are observed beneath the D-E junction in approximately 50% of cases. A moderate increase in the number of dermal mast cells and macrophages are observed in 30-50% of LPP lesional biopsies. Eosinophil numbers are low. Folliculitis and furunculosis are uncommon findings. Although dermal fibroplasia is a prominent finding in dogs with LPP, dermal granulomas are uncommon.

Interpretation and response to treatment The interpretation of lymphoplasmacytic infiltrates in skin biopsies is a subject of debate, with some veterinary dermatopathologists viewing them as a common non-specific finding at glabrous and mucocutaneous skin sites. However, the presence of large numbers of lymphocytes and plasma cells within a lesion typically suggests antigenic stimulation and immune reactivity. Although most chronic non-specific dermatitides in the dog contain some lymphoid cells within the inflammatory infiltrate, these cells do not usually dominate the histological appearance of the lesion. Lymphoplasmacytic infiltrates have previously been reported in both antibiotic-responsive (AbR) and immunomodulatory-responsive (ImR) dermatoses in the dog. As recurrent interdigital pyoderma is a common cause of relapsing pododermatitis, it is initially advisable to employ a combined approach of culture, cytology, biopsy and response to antimicrobial therapy to try and determine which of these cases are truly antibiotic-responsive. If the response to such therapy is poor, most affected individuals will typically display a marked clinical improvement over a 2-8 week period in response to immunosuppressive doses of prednisolone or cyclosporine (hence the term “ImR-LPP”). Affected individuals display significantly improved scores for pruritus, erythema, alopecia and skin thickening at the 8-week time point post treatment initiation. Longer-term control is typically achieved following gradual tapering of the dose administered once clinical signs have ameliorated. The tapered dose of prednisolone required to maintain longer-term control is usually 0.5-1.0 mg/kg q48h, while the corresponding dose for cyclosporine is 1.5-4.5 mg/kg q48h.

CHARACTERISATION OF IMMUNE RESPONSES IN DOGS WITH IMR-LPP

CD1c expression for dendritic cells The median numbers of CD1c + dendritic cells (DCs) in the epidermis and dermis of dogs with ImR-LPP are significantly increased compared to healthy controls. In addition to increased numbers, the dendritic branches of DCs are more prominent and interdigitating in ImR-LPP dogs compared to controls. Focal aggregates of positively stained interstitial DCs are most prominent immediately beneath the D-E junction and in the superficial dermis. In addition, small clusters of DCs (typically 6-12 cells/site) can be found in perivascular spaces and at diffuse sites throughout the dermis. These clusters are often observed in close proximity to mononuclear inflammatory cells.

MHC class II expression The median numbers of MHC class II + cells in the epidermis and dermis of dogs with ImR-LPP are significantly increased compared to healthy controls. Positive staining for MHC class II antigens is present in the epidermis of virtually all dogs with ImR-LPP; intense intra-epidermal staining is typically associated with DCs and mononuclear inflammatory cells. In ImR-LPP dogs, dermal staining for MHC class II molecules is associated with a wide variety of cell types including interstitial DCs, mononuclear inflammatory cells, fibroblast-like cells and vascular endothelium. Most lymphocyte class II-associated staining is observed in clusters in perivascular regions and below the D-E junction. The stimuli resulting in the accumulation of DCs and MHC class II + cells in the lesions of ImR-LPP are currently unknown. Despite this, the DC hyperplasia and increased MHC class II + cell numbers evident in lesional ImR-LPP skin are consistent with enhanced antigen presentation. These data suggest that DCs and MHC class II antigens may possibly contribute to the underlying pathogenesis of ImR-LPP through the priming and activation of T cells in dogs with this disease. 8 T AND B LYMPHOCYTE RESPONSES IN DOGS WITH IMR-LPP

Serum Immunoglobulins The median serum concentrations of IgA, IgG and IgM in dogs with ImR-LPP are significantly elevated when compared to clinically healthy controls (P < 0.01 for all three isotypes). Thus, while a crude measure, the global humoral immune response in peripheral blood is up-regulated.

Lymphocyte proliferation assays Dogs with ImR-LPP have comparable stimulation indices for a variety of T- and B-cell mitogens when compared to a healthy control group. Although a relatively crude test, there is thus no evidence for impaired cell-mediated immunity in the peripheral blood of affected individuals.

Lymphocyte phenotyping studies in peripheral blood Absolute CD3 +, CD4 +, CD8 + and CD21 + cell counts in the peripheral blood of ImR-LPP dogs are not significantly different from healthy controls. However, the median CD8 +/CD3 + T cell ratio is significantly higher in dogs with ImR-LPP.

Skin infiltrating lymphocytes The median CD3 +, CD4 +, CD8 + and CD21 + cell counts in the epidermis and dermis of dogs with ImR-LPP are significantly elevated in comparison to healthy controls (P < 0.01 for all four cell subsets). Although present in all layers of the living epidermis, focal clusters of CD3 +, CD4 + and CD8 + T cells in the ImR-LPP group are primarily restricted to the stratum basale and stratum spinosum. Dermal CD3 +, CD4 + and CD8 + T cells are observed in perivascular sites in the superficial dermis, beneath the D-E junction and periadnexally. Though small numbers of CD3 + cells are observed in the infundibular mural region of some dogs with ImR-LPP, they are rarely observed in lower regions of the follicle wall. Calculation of the ratio of dermal CD4 +/CD8 + cells is meaningless as the combined CD4 + and CD8 + counts exceeded the CD3 + count in 50% of affected individuals. CD21 + cells are typically observed in the epidermis of 85% of dogs with ImR-LPP; staining is largely confined to interepithelial sites in the stratum basale and stratum spinosum. Positive staining in the ImR-LPP group for B cells is evident in clusters in perivascular spaces in the superficial dermis, below the D-E junction and in the dermal interstitium. Although CD21 + B cells are observed in the regions surrounding the epitrichial glands, sebaceous glands and hair follicles of dogs with ImR-LPP, positive staining within the follicle wall is uncommon.

CYTOKINE PROFILES IN LESIONAL AND NON-LESIONAL IMR-LPP SKIN

A study was conducted to quantify the expression of mRNA encoding Th 1 (IFN- , IL-2 and IL-12), Th 2 (IL-4 and IL-6) and immunomodulatory cytokines (IL-10 and TGF- )γin lesional ImR-LPP, non-lesional ImR-LPP and healthy control pedal skin. Gene transcripβts were quantified using TaqMan real-time reverse transcriptase-polymerase chain reaction (RT-PCR) assays. ImR-LPP skin had significant over-expression of IL-6 mRNA (P < 0.05) and significant under- expression of IL-12 mRNA (P < 0.01) compared to healthy controls. In addition, lesional ImR-LPP skin had significantly higher levels of IL-10 transcripts compared to healthy control pedal skin (P < 0.05). Although not attaining significance (P = 0.07), a trend towards reduced TGF- mRNA expression in lesional ImR-LPP skin was also evident. There were no significant differβences in the levels of IFN- or IL-2 mRNA transcripts among the three skin sample sources. IL-4 mRNA was detected in onlyγone lesional sample. These results suggest that the pathogenesis of ImR-LPP may be associated with a T-cell mediated inflammatory response characterized by impaired Th 1-like, but enhanced Th 2-like cytokine expression.

9 NOTES

10 THE CANINE FOOT AS A PREDILECTION SITE FOR DISEASE Rory Breathnach

AETIOLOGY OF CANINE PODODERMATITIS Pododermatitis is a common and frequently debilitating inflammatory disease of the pedal skin of dogs. The clinical history is often characterised by periods of disease exacerbation and remission, although some dogs have lesions that persist and involve all four feet. Although pododermatitis may occur as a separate entity, many cases of pedal inflammation represent simply one component or manifestation of an otherwise more extensive dermatological disease. Several review articles have attempted to classify the various microbial, parasitic and immunological diseases that may result in pedal involvement. The techniques used to confirm a diagnosis in each case are outlined in Table 1 (See page 18).

Infectious causes

Bacteria Bacterial infection involving the pedal skin is frequently reported in the dog. The principal pathogen involved in canine pyoderma is Staphylococcus intermedius . However, many authors have stated that any bacterial involvement in pododermatitis invariably results from secondary infection, and that a wide range of different organisms may be involved. Secondary opportunistic bacteria that have been isolated in such cases include Proteus spp., Pseudomonas aeruginosa and Escherichia coli . Chronic or relapsing pyoderma of the foot may be associated with immunosuppression. Immunosuppressive diseases that may predispose dogs to chronic interdigital pyoderma include hypothyroidism, hyperadrenocorticism and diabetes mellitus. The diagnosis of interdigital pyoderma may be confirmed by cytology, bacterial culture and/or biopsy of affected skin. Atypical infections of the pedal skin with Mycobacteria spp., Nocardia spp. and Actinomyces spp. are reported infrequently in the dog.

Fungi Dermatophyte infections, including those caused by Microsporum spp. and Trichophyton spp., may occasionally involve the feet of dogs. The lesions may vary markedly in appearance and manifest as alopecia, erythema, scaling or more rarely, inflammatory plaques. At the time of clinical examination, superimposed bacterial infection can also be present. Dermatophyte infections of the foot may involve the nail or the nail bed. Dermatophytosis is a potential zoonotic disease, necessitating a prompt diagnosis in order to minimize the risk of infection spreading to man. Fungal infections of the pedal skin due to Candida spp. and Malassezia pachydermatis have also been reported in the dog. Some authors have suggested a specific aetiological role for M. pachydermatis in canine pododermatitis. Increasing warmth and humidity can result in a higher incidence of skin infections with this latter ubiquitous yeast. Many affected dogs are reported to suffer from another underlying disease condition that predisposes to M. pachydermatis infection. Other mycotic diseases of the foot tend to occur deep within the dermis or subcutaneous tissue. Intermediate (subcutaneous) mycoses are defined as fungal infections that have invaded the living (i.e. non-keratinized) layers of the skin. Traumatic wounds to the skin represent the most common route of entry for these mainly saprophytic organisms. Prototheca spp. and Sporothrix schenckii have both been isolated from intermediate mycoses in the dog. Mycetomas represent a unique infection in which the causal organism is present in tissues in the form of grains or granules that subsequently give rise to abscess formation, erosions and the discharge of purulent granular material. Deep or systemic mycoses are fungal infections of internal organs that may disseminate to the skin via the bloodstream, as reported for Blastomyces spp. and Cryptococcus spp. However, skin lesions resulting from primary cutaneous inoculation of these fungi are rare. Nodular masses and draining sinus tracts are the major manifestations of intermediate and deep mycotic infections of the skin. Lesions may be single or multiple. In the case of deep or systemic mycotic infections, other clinical signs of ill health are usually present.

11 Ectoparasites Various parasitic species have been directly incriminated in the aetiology of canine pododermatitis. Demodectic mange is an inflammatory parasitic skin disease of dogs that may affect the feet. Although Demodex canis is a normal inhabitant of canine skin, demodectic mange is characterized by the presence of a larger than normal number of demodectic mites within the skin. Whilst D. canis mites usually live within the hair follicles, a smaller number of mites have been detected within the sebaceous glands. Mason (1993) reported the discovery of a new, shorter demodectic mite in the dog. This shorter variant is normally observed within the stratum corneum of the epidermis and not within the hair follicle. Subsequent to this, another long-bodied demodectic mite was also identified within the hair follicle. The clinical significance of these latter two variants or species of mite still remains unclear. Pododemodicosis may occur as a specific entity or as part of a more generalized demodectic mite infestation. Heavily parasitized follicles are prone to secondary bacterial infection. Several theories on immune system dysfunction have been proposed in an effort to explain why some dogs are predisposed to the development of demodicosis. Neotrombicula autumnalis is a scavenging mite whose adult stages survive on decaying vegetation. The larval stages of N. autumnalis may parasitize any skin surface of the dog that comes in direct contact with the ground, including the feet. Larval feeding often results in moderate to severe irritation and a pruritic, papulocrustous eruption. Some dogs may actually become sensitized to N. autumnalis.

Endoparasites Larval stages of helminth parasites that may penetrate the pedal skin of dogs include Pelodera strongyloides , and the hookworm species Ancylostoma caninum and Uncinaria stenocephala . These helminth species are more commonly associated with disease in groups of dogs, particularly when the animals are kept in kennels or runs contaminated with faecal material. Dermatological signs may be present at sites other than the feet. The affected skin is erythematous and alopecic in Pelodera dermatitis . Papules, crusts and secondary bacterial infection are commonly present. Although pruritus may vary in severity, it is usually mild. Hookworm dermatitis is commonly reported in grouped dogs, such as greyhounds and foxhound packs. Pedal involvement is characterized by the presence of erythema, heat, swelling and pain in the skin between the toes. The footpads are frequently soft and spongy, with hyperkeratosis of the pads being commonly observed in more chronic cases.

Protozoa Protozoal parasites such as Leishmania spp. are reported to cause pedal skin lesions in dogs in certain regions of the world. Clinical signs vary in severity but include erythema, scale, erosions and ulcers. Hypertrophy of the toenails has also been reported.

Pododermatitis arising as a result of hypersensitive causes Hypersensitive skin diseases in the dog commonly involve the pedal skin. Most of these dogs have a history of intermittent, persistent or seasonally recurrent clinical signs of skin disease.

Atopic dermatitis Canine atopic dermatitis (AD) has recently been re-defined as a genetically predisposed inflammatory and pruritic allergic skin disease with characteristic clinical features, that is associated most commonly with IgE antibodies to environmental allergens. Although the precise pathogenesis of canine AD remains unclear, the percutaneous absorption of allergen, with subsequent processing by Langerhans cells, is likely to be the initial step involved in the induction and development of AD. Studies conducted in vitro have demonstrated that Langerhans cells are involved in IgE-dependent antigen presentation to autologous T cells. This may subsequently result in a preferential expression of allergen-specific Th2 cells that elaborate a number of different cytokines. This imbalance in the ratio of Th2 to Th1 cells, and the shifting concentrations of different cytokines produced by these cells, results in enhanced production of allergen-specific IgE by B lymphocytes/plasma cells. However, the pattern of cytokine expression in the skin lesions of AD may vary according to the age of the lesion. Some authors have suggested that the role of IgE in the pathogenesis of AD may relate more to enhancement of antigen-presenting cell (APC) function in Langerhans cells (and other APCs) than to the triggering of mediator and cytokine release by mast cells.

12 Certain breeds are known to be predisposed to developing AD including Cairn terriers, West Highland white terriers, golden retrievers, Labrador retrievers, boxers and English setters. The time of first onset of clinical signs usually varies between 6 months and 7 years of age. Zur et al . (2002) reported a mean age of onset of 1.7 years in a retrospective survey of dogs with AD. Although clinical signs may vary, the dominant presenting complaint is pruritus. The resultant self-trauma can lead to secondary changes which include erythema, papules, pustules, alopecia and lichenification. Other complications include secondary bacterial infection, Malassezia dermatitis and seborrhoea. The most commonly affected sites on the body include the face, feet, axillae, inguinal regions, the extensor surface of the carpi and the flexor surface of the tarsi. AD is a common cause of pedal dermatitis in the dog. Conjunctivitis and otitis externa have been described in approximately 50% of affected dogs. Clinical signs of AD may occur on a seasonal or perennial basis. The range of potential allergens is exhaustive. Although a diagnosis was traditionally based on satisfying the criteria of Willemse (1986), in more recent times AD has largely been a diagnosis based on history, clinical signs and the exclusion of all other resembling pruritic dermatoses.

Contact dermatitis Contact dermatitis may be divided into two distinct sub-categories, irritant contact dermatitis and allergic contact dermatitis. The true incidence of allergic contact dermatitis appears to be low. A wide range of substances in the animal’s environment may induce a hypersensitive skin response, and contact surfaces other than the foot may additionally become involved. The offending allergens are often synthetic agents including carpet cleaners, disinfectants and resins. Allergic contact dermatitis has also been reported following exposure to various plant leaves and other vegetative material, including cedar wood and Hippeastrum . Clinical signs are common on the feet and include erythema, papules, alopecia and pruritus. Allergic contact dermatitis is a delayed-type hypersensitive reaction.

Food hypersensitivity Canine food hypersensitivity is a non-seasonal and highly pruritic skin disorder. However, food hypersensitivity in dogs may often be confused with food intolerance. No age, sex or breed predispositions have been reported for this disease in the dog. Clinical signs are highly variable and include manifestations such as urticaria, anaphylaxis and pruritic dermatosis. Concurrent alimentary tract involvement is reported in only 10-15% of cases. The dominant complaint in canine food hypersensitivity is pruritus, with self-trauma resulting in the development of erythema, alopecia and secondary bacterial and Malassezia skin infections. Papules and wheals may be observed as primary lesions in certain cases. Although any site on the body can be affected, the feet, face, ears, axillae, groin and caudal thighs are commonly involved. The pruritus reported is often severe and lesions may be present on all four feet. A wide range of potential allergens in the animal’s diet has been incriminated in this disease. In vitro serologic tests to detect allergen-specific IgE and intradermal skin test challenge are unreliable methods for confirming a diagnosis of food hypersensitivity in the dog.

Drug hypersensitivity Cutaneous drug eruptions are a group of variably pruritic, though uncommon, dermatoses in the dog. However, as cutaneous drug reactions can mimic virtually any form of skin disease, efforts to establish an accurate diagnosis can be problematic. Individual cases of erythema multiforme, toxic epidermal necrolysis, lupus erythematosus and vasculitis have all been attributed to therapy with various medicinal products. Clinical signs may include papules, plaques, erosions and ulcers that involve the pedal skin, pads and skin-pad margins. There are no age or breed predilections in general, although certain breeds do appear more susceptible to reactions to specific drugs e.g. Doberman pinschers and sulphadiazine. It is generally advised that the presence of pedal or other cutaneous lesions in any dog receiving medication should alert the clinician to a possible iatrogenic role in lesion development. Cessation of drug administration should normally result in a gradual resolution of the clinical signs over a period of days to weeks in a true case of cutaneous drug eruption.

Bacterial hypersensitivity Bacterial hypersensitivity is an uncommon, though severely pruritic, pustular dermatitis that is postulated to occur as a result of a hypersensitive reaction to staphylococcal antigens. In dogs, it has been proposed that bacterial hypersensitivity may represent either a type I- or a type III-hypersensitive reaction. The lesions are commonly referred to as “target” lesions,

13 with erythematous zones that spread peripherally and may coalesce. The majority of affected dogs have a co-existing dermal disease such as atopic dermatitis, flea allergic dermatitis or hypothyroidism. Pedal involvement may be particularly severe in some dogs with bacterial hypersensitivity. Skin biopsies from lesional sites usually reveal varying degrees of vasculitis and intraepidermal pustules, folliculitis or furunculosis.

Fungal hypersensitivity Increasing attention has begun to focus on the potential role of fungal hypersensitivity in the pathogenesis of skin diseases in man, although the true incidence of this disorder in the dog is difficult to ascertain. A hypersensitive reaction to Candida spp. has been suggested in some dogs with paronychia, whilst a similar reaction to Malassezia pachydermatis may result in clinical signs involving the feet. It has also been proposed that the pathogenesis of fungal kerions could involve the development of a hypersensitive reaction to dermatophytes.

Pododermatitis arising as a result of autoimmune causes

Pemphigus complex Four distinct sub-classifications of the pemphigus complex are recognized in the dog, although all appear to possess a similar underlying pathogenesis. It is postulated that the initial step in disease development may involve the production of an autoantibody to the glycocalyx of the keratinocyte cell membrane. The antigens involved are heterogeneous, associated with desmosomal components, and may differ from one form of the disease to the next. Pemphigus foliaceus may commonly involve the pedal skin of dogs. Although the clinical signs observed in pemphigus foliaceus are largely similar to those reported for the other three forms of disease i.e. vulgaris, vegetans and erythematosus, the incidence of pedal involvement is lower for these latter three forms. Crusts and ulcers are commonly observed on the feet and footpads, although intact blisters and bullae may also be evident. Erythema, pustules, alopecia and epidermal collarettes have all been described at the affected site, whilst peeling, fissuring, swelling and ulceration at the skin-pad margin are reported in some cases involving the footpads. Characteristic histopathological findings in skin biopsies may be strongly supportive of a diagnosis of pemphigus complex in the dog. Direct immunofluorescence or immunoperoxidase staining techniques applied to lesional skin biopsies may reveal autoantibodies targeted against the epidermal glycocalyx in some, though not all cases of canine pemphigus. Various laboratory techniques capable of detecting circulating autoantibodies in serum have also been described.

Bullous pemphigoid Bullous pemphigoid is a vesico-bullous, ulcerative skin disease in which the epidermal basement membrane zone is the intial site of autoantibody attack. Some of the specific antigenic components in collagen targeted by the IgG autoantibodies in this region have recently been identified in the dog. Complement fixation, along with neutrophil and eosinophil infiltration at the affected site, is thought to play an important role in the pathogenesis of bullous pemphigoid in the dog. Drug provocation and exposure to ultraviolet light may predispose dogs to the development of this disease. Lesions are commonly present in the mouth, mucocutaneous junctions, footpads and nailbeds. Clinical signs are similar to those reported for the pemphigus complex, although they may be more severe and widespread in bullous pemphigoid.

Systemic lupus erythematosus Systemic lupus erythematosus (SLE) is a complex autoimmune disease that may potentially affect a variety of different tissues in the body. Several theories exist in relation to the origin of skin lesions in SLE. It has been suggested that ultraviolet light may penetrate down to the basement membrane zone in genetically susceptible individuals, altering the keratinocyte surface and allowing the expression of previously sequestered antigens in either the cytoplasm or nucleus of the cell. Antibodies directed against these antigens then attach to the keratinocyte surface, resulting in a cytotoxic reaction involving the cell. Inflammatory mediators and immunomodulatory agents are also released, leading to infiltration of the affected tissues by lymphocytes and histiocytes. Skin lesions observed in SLE commonly include vesicles, bullae and ulcers on the face, ears, distal limbs, feet and nasal planum. Erosion and ulceration of the footpads have also been

14 reported. Secondary pyoderma and seborrhoea are sometimes present. Although pruritus is variable, it may be particularly marked on certain occasions. In the majority of dogs, clinical signs related to the involvement of other organ systems are usually present. Abnormal haematological findings in patients with SLE may include anaemia, leucopoenia or leucocytosis, and thrombocytopenia. Hypergammaglobulinaemia and proteinuria are additional non-specific findings reported in some affected dogs.

Discoid lupus erythematosus Discoid lupus erythematosus (DLE) is considered by many authors to be a benign form of SLE, in which the clinical signs of disease are limited to the skin. Lesions are usually confined to the face and include depigmentation, erythema, scaliness, ulceration and crusting over the nasal region. However, similar lesions are also reported around the feet and footpads. Ultraviolet light is thought to play a role in predisposing to the development of DLE.

Cold agglutinin disease Cold agglutinin disease is a rare cutaneous disorder of dogs that may affect the feet. Certain proteins, such as cryoglobulins and cryofibrinogens, can precipitate from blood upon cooling. The globulin fractions involved may be monoclonal or polyclonal, and may be associated with disease processes as diverse as infections, autoimmune diseases and neoplasia. Precipitation of these proteins may lead to significant vascular pathology through obstruction, thrombosis, and stasis of blood flow. Cold agglutinin disease generally affects body extremities such as the feet, nose, ears and tail. Clinical signs include erythema, necrosis, purpura and ulceration. Exposure to cold environmental conditions ( ≤4°C) is usually a relevant factor in the animal’s history. Despite possessing a wide range of thermal activity (0-37°C), cryopathic autoantibodies exhibit maximum activity at lower temperatures of 0-4°C. Cold agglutinin disease represents a type II hypersensitive reaction, and has been associated with lead poisoning in dogs.

Pododermatitis arising as a result of endocrine causes

Hypothyroidism Although endocrine disorders would be considered an uncommon cause of primary pedal skin disease, immunosuppression associated with hypothyroidism and hyperadrenocorticism can result in bacterial, fungal or parasitic infections at this site. Thyroid hormones play an important role in the differentiation and maturation of skin, follicular activity and the regulation of many aspects of cutaneous metabolism. Low thyroid status may impair the physical barrier function of skin. In addition, thyroid hormones play an important role in the development of mammalian lymphoid tissue, and low serum triiodothyronine (T 3) and thyroxine (T 4) concentrations have been associated with impaired neutrophil and lymphocyte function. These essential roles help to explain why bacterial pyoderma is a frequent complication of hypothyroidism in the dog. Hypothyroidism can also predispose dogs to secondary Malassezia dermatitis and otitis externa, and adult-onset demodicosis. Haematological evaluation of dogs with hypothyroidism may reveal a non-regenerative anaemia, whilst biochemical analysis frequently reveals elevated concentrations of cholesterol, alanine aminotransferase, alkaline phosphatase and creatine kinase.

Hyperadrenocorticism The immunosuppressive effects of excess glucocorticoids in hyperadrenocorticism have been associated with secondary microbial infection and adult-onset demodicosis of the pedal skin in dogs. In some reported cases, the clinical signs of demodicosis have been confined to the foot. A tentative diagnosis of hyperadrenocorticism is initially based on the history and presenting clinical signs. The diagnosis is confirmed according to the tests specified in Table 1 (See p18).

Hepatocutaneous syndrome Hepatocutaneous syndrome is an uncommon disorder of the dog that has been variably described as diabetic dermatosis, necrolytic migratory erythema or glucagonoma syndrome. Although many reports in the human literature document the presence of a glucagon-secreting tumour within the pancreas of affected patients, only a small percentage of dogs have a demonstrable pancreatic mass. Instead, the majority of canine patients have evidence of advanced hepatic disease. Whilst the precise nature of the hepatopathy may differ between dogs, hepatic cirrhosis is commonly reported at post-mortem examination. Hyperglucagonaemia may occur in some dogs with hepatocutaneous syndrome. Affected animals usually present with severe cutaneous lesions including erythema, crusting, oozing

15 and ulceration of the face, muzzle, genitalia, distal limbs and footpads. Hyperkeratosis and ulceration of the footpads are commonly reported. A history of systemic signs including weight loss, inappetance and lethargy for a period of weeks to months prior to the onset of cutaneous signs is often present. Biochemical analysis usually reveals marked elevations in serum hepatic enzyme concentrations, hypoalbuminaemia and increased postprandial bile acid concentrations.

Pododermatitis arising as a result of environmental causes

Irritant contact dermatitis Irritant contact dermatitis is an inflammatory disease caused by direct contact of the skin with an offending substance. The substance involved could be an irritant, toxin or harsh physical stimulus. Primary irritant contact dermatitis may occur in dogs without any prior history of exposure or sensitization to that agent. The foot is a common site for lesions of irritant contact dermatitis. Highly corrosive substances tend to produce more immediate and severe reactions than less corrosive agents. A long list of substances has been incriminated in the aetiology of pododematitis including disinfectants, salts, fertilisers, urine and various herbicidal sprays. Clinical signs may include erythema, pain and ulceration of the pedal skin. The resultant pruritus can vary from mild to intense. Other potential causes include: • Trauma • Foreign-body dermatitis • Toxins In spite of its current ban in many countries, the rodenticide thallium is still reported to cause cutaneous and mucosal disease in the dog when ingested over a prolonged period of time. Pedal lesions consist of erythema, alopecia, crusts and ulceration of the interdigital skin. Cutaneous lesions at other body sites, along with systemic signs of ill health, have also been reported. The skin lesions are usually non-pruritic.

Pododermatitis associated with hyperkeratotic, nodular and pigmentary dermatoses

Zinc-responsive dermatosis True zinc deficiency in the dog is rarely observed, with the exception of Bull terriers with acrodermatitis. However, zinc-responsive dermatoses have been infrequently described in the dog. The condition usually manifests as one of two distinct syndromes. The first syndrome has been recognized in the Siberian husky, Alaskan malamute and other breeds in which a genetically programmed defect in intestinal zinc absorption is considered to be responsible for the problem. Many of these dogs have dietary concentrations of zinc well within the internationally recommended range, but the failure to adequately absorb this trace element from the bowel results in deficiency. In the second syndrome, rapidly growing puppies fed on poor quality diets, or diets over- supplemented with minerals (especially calcium) and vitamins, can suffer from a relative zinc deficiency. This deficiency may arise from the low concentrations of zinc in the diet, excess binding of zinc in the intestine by calcium or phytates, or a combination of both of these factors. Irrespective of which syndrome occurs, the clinical signs are essentially similar. There is crusting and scaling of the mucocutaneous junctions, elbows and footpads. Plaque-like lesions, fissuring and hyperkeratosis of the footpads may occur. Claw disease, particularly onychomalacia, has also been observed in affected dogs. Secondary bacterial and Malassezia skin infections are common, particularly if pruritus is present. A similar entity to that just described was reported in the 1980s, and was commonly referred to by the term “generic dog food dermatosis”. The clinical signs and histopathological features of lesional biopsies were remarkably similar to those reported for zinc-responsive dermatosis. However, generic dog food dermatosis was more rapid in onset and many animals also displayed systemic signs of ill-health (Sousa et al. , 1988). The cutaneous and systemic signs invariably resolved once the diet was changed to one that complied with the National Academy of Sciences minimum nutritional requirements for dogs.

Digital hyperkeratosis Digital hyperkeratosis (with or without involvement of the nasal planum) has been reported in middle to older aged dogs of several breeds. Lesions may adopt a vegetative, grooved,

16 ridged or even feathered appearance. The pads may become fissured and painful in the more advanced cases, especially in larger breeds of dogs. Kerry blue terriers and Irish terriers may be predisposed to a specific form of digital hyperkeratosis, termed “familial footpad hyperkeratosis”. Although still uncertain, recent work suggests that an autosomal recessive mode of inheritance may be responsible for this condition. Affected dogs usually develop severe hyperkeratosis of the footpads by 6 months of age, and all pads on all four feet are usually involved.

Sterile (pyo)granulomas Sterile (pyo)granulomas are infrequent idiopathic lesions that occasionally affect the pedal skin. Clinical signs usually consist of multiple thickened or nodular lesions that are sometimes accompanied by draining sinus tracts. In addition to the feet, many affected dogs also have lesions on the face and ears. Pruritus and pain are mild or absent in most cases. Histopathological examination reveals pyogranulomatous dermatitis, although bacterial and fungal cultures of lesional material are invariably negative. In the early stages of disease, the granulomatous lesions may track, though not actually involve, the hair follicles. A form of sterile pyogranuloma peculiar to the German shepherd has been reported. Although pathology is present in the pedal skin of these German shepherds, the clinical signs primarily consist of sinus tracts that open to the surface above the level of the metacarpal or metatarsal pads.

Nodular dermatofibrosis syndrome Nodular dermatofibrosis syndrome is a rare generalized disease primarily reported in the German shepherd dog. More recently, the disease has been recognized in the Boxer, Labrador and various mixed-breeds of dog. This syndrome is characterized by the presence of nodular skin growths at many sites, including the feet. Based upon histopathological criteria, the lesions are classified as collagenous nodules or nevi. A symmetrical appearance to the lesions may sometimes be observed. An autosomal dominant mode of inheritance has been proposed in the German shepherd. Clinical case reports often document an acute onset of lesions in young to middle aged dogs. Most affected animals also have concurrent renal cyst adenocarcinoma lesions.

Neoplasia This is another potential cause of lesions of this type Pododermatitis arising as a result of psychogenic and neurological causes Psychogenic dermatoses represent a diverse group of diseases in which cutaneous lesions result from self-induced damage in animals with psychological disturbances. Acral lick dermatitis manifests as one or more areas of thickened, raised skin with alopecia, partial to full thickness ulceration and clearly defined demarcations. Commonly affected sites include the cranial aspect of the lower limbs, especially around the carpus or the toes. Most affected dogs belong to the larger breeds, with Labrador retrievers and Doberman pinschers being over-represented. The lesions appear to develop as a direct result of the animal’s licking behaviour at that site. Although efforts must be made to identify any underlying organic cause to the problem e.g. osteomyelitis or a foreign body, no such cause is identified on most occasions. Acral mutilation syndrome is a rarely reported disease of English springer spaniels, German short-haired pointers and English pointers. This syndrome involves a sensory neuropathy, in which abnormalities have been recorded in the spinal cord, spinal roots, ganglia and peripheral nerves. The mode of inheritance appears to be autosomal recessive in affected dogs. Clinical signs are observed in the first few months of life and include severe licking and biting at the feet, followed by analgesia and loss of temperature sensation in the toes. The effects may extend further up the limb. The hind legs tend to be more severely affected, with affected toes and footpads becoming swollen and ulcerated. Auto-amputation of the toes may occur.

17 Table 1. Diagnostic/ancillary tests recommended to help confirm the aetiology in dogs with pododermatitis

Aetiology Diagnostic/ancillary tests recommended Infectious diseases • Bacterial dermatitis Cytology, culture and biopsy. PCR for some atypical Mycobacteria spp. • Dermatophytosis Wood’s lamp (certain species), KOH of skin scrapings/hair plucks, culture • Malassezia dermatitis Cytology, culture on Sabouraud’s agar or modified Dixon’s agar, biopsy • Intermediate/deep mycoses Biopsy, culture of lesional tissue samples • Demodicosis Skin scrapings, biopsy • Neotrombicula infestation Visual inspection, microscopy • Pelodera dermatitis Skin scrapings, biopsy. Modified Baermann technique on litter • Hookworm dermatitis Faecal flotation test • Leishmaniosis Biopsy. PCR for leishmanial DNA in lesional tissue Hypersensitive diseases • Atopic dermatitis History, clinical signs and exclusion of resembling pruritic dermatoses • Food hypersensitivity Food trial using a novel protein source • Contact allergic dermatitis History, avoidance of suspect allergen, patch testing • Drug hypersensitivity History, skin biopsy, basophil degranulation test possible • Bacterial hypersensitivity Biopsy, intradermal skin testing using staphylococcal extract(s) • Fungal hypersensitivity Biopsy, intradermal skin testing using fungal extract(s) Autoimmune diseases • Pemphigus complex Biopsy, immunohistochemical staining (IgG, IgA, IgM, complement C3) • Bullous pemphigoid Biopsy, immunohistochemical staining (IgG, IgA, IgM, complement C3) • Systemic lupus erythematosus Biopsy, immunohistochemical staining (IgG, IgA, IgM, complement C3) • Discoid lupus erythematosus Biopsy, immunohistochemical staining (IgG, IgA, IgM, complement C3) • Cold agglutinin disease Biopsy, serological testing for cold-reacting autoantibodies Endocrine diseases • Hypothyroidism Biopsy, thyroid function tests, scintigraphy of thyroid gland • Hyperadrenocorticism ACTH stimulation and dexamethasone suppression tests, ultrasound • Hepatocutaneous syndrome Skin biopsy, serum biochemistry, ultrasound and FNA/biopsy of liver Environmental causes • Irritant contact dermatitis History, clinical signs, avoidance of suspect irritant • Trauma History, clinical signs • Frost bite History, clinical signs • Foreign body dermatitis Surgical exploration of site, biopsy Hyperkeratotic, nodular and pigmentary dermatoses • Zinc-responsive dermatosis Biopsy, dietary or breed history. Serum/hair zinc concentrations variable • Digital hyperkeratosis Biopsy, exclusion of other causes of hyperkeratosis • Sterile (pyo)granuloma Biopsy • Nodular dermatofibrosis Biopsy ± ultrasound and biopsy of kidney lesions Psychogenic/ neurological • Acral lick dermatitis History, clinical signs, biopsy, exclusion of other causes • Acral mutilation syndrome History, biopsy of affected nerve tissue

18 SYMMETRICAL LUPOID ONYCHODYSTROPHY Rory Breathnach

Abstract not Submitted NOTES

19 NOTES

20 UVEODERMATOLOGICAL SYNDROME – AN OPHTHALMOLOGIST’S APPROACH W.J.Carter BVetMed DVOphthal MRCVS RCVS Recognised Specialist in Veterinary Ophthalmology Exeter Veterinary Ophthalmology Referrals

INTRODUCTION Uveodermatological syndrome (UVD) is a chronic panuveitis with cutaneous involvement resulting in vitiligo and poliosis, which was first described in two Japanese Akitas in 1977 1. Since then, other case reports have been published documenting a similar syndrome in other breeds such as the Siberian Husky and Golden retriever, although the majority of cases have been in the Japanese Akita 1,2,3,4,5,6,7,8,9,10,11,12,13 .

What is uveitis? Inflammation of the uveal tract which is made up of the iris, ciliary body and choroid (coloured in grey)

choroid

Clinical signs of panuveitis/uveitis • Pain, photophobia, blepharospasm and lacrimation • Ocular redness, often most marked in perilimbal area above the ciliary body (perilimbal hyperaemia) • Mild corneal opacity • Aqueous flare • Loss of iris detail, iris may be swollen (and anterior chamber shallow) • Constricted (miotic) pupil • Low intraocular pressure • Tapetal and non tapetal hyporeflectivity due to retinal and subretinal oedema • Bullous retinal detachments or total detachments depending on severity of disease • Optic neuritis (Loss of nerve head detail, swollen and hyperaemic) • Variable effect on vision, but may be acutely blind (especially if there is posterior segment involvement e.g. panuveitis)

21 Uveodermatological Syndrome (UVD) or Vogt-Koyanagi-Harada Like Syndrome Uveodermatological syndrome normally affects young adult dogs with a mean age of three years and is most commonly seen in the Japanese Akita, Samoyed, Shetland Sheepdog and Siberian Husky, although other breeds including the Golden Retriever and Irish Setter have been reported. This disease in our canine patients falls into two main types:- 1. Acute disease- These cases often only present with ocular signs and may never develop on to show cutaneous lesion as due to the nature of the disease they may be euthanased prior to skin lesions manifesting. 2. Chronic disease- these present with clinical or subclinical uveitis that is easily controlled with topical or low dose systemic medications and progress to show cutaneous lesions as well. The medical ophthalmologists (International VKH Workshop Group) have categorised this disease to a much greater degree than in the veterinary world and have drawn up criteria for its classification. This does not necessarily agree with the disease presented in the veterinary literature and so we have tended to call it VKH-like disease or Uveodermatological syndrome (UVD).

Complete VKH: Criteria 1–5 must be present Incomplete VKH: Criteria 1–3 and either 4 or 5 must be present Probable VKH (isolated ocular disease): Criteria 1–3 must be present

1. No history of penetrating ocular trauma or surgery preceding the initial onset of uveitis 2. No clinical or laboratory evidence suggestive of other ocular disease entities 3. Bilateral ocular involvement (a or b must be met, depending on the stage of disease when the patient is examined) a) Early manifestations of disease • Evidence of diffuse choroiditis (with or without anterior uveitis, vitreous inflammatory reaction, or optic disk hyperemia) which may manifest as (a) focal areas of subretinal fluid, or (b) bullous serous retinal detachments b) Late manifestations of disease • History suggestive of prior presence of early findings noted in 3a and either (1) or (2) below, or multiple signs from 3. 1. Ocular depigmentation: either (a) sunset glow fundus or (b) Sugiura’s sign 2. Other ocular signs including (a) nummular chorioretinal depigmented scars, or (b) retinal pigment epithelium clumping and/or migration, or (c) recurrent or chronic anterior uveitis 4. Neurological/auditory findings (may resolve by time of evaluation) a) Meningismus (malaise, fever, headache, nausea, abdominal pain, stiffness of the neck and back, or a combination of these factors); note that headache alone is not sufficient to meet the definition of meningismus b) Tinnitus c) Cerebrospinal fluid pleocytosis 5. Integumentory finding (not preceding onset of central nervous system or ocular disease) a) Alopecia, or b) Poliosis (leukotrichia), or c) Vitiligo

22 Canine UVD has been likened to human Vogt-Koyanagi-Harada (VKH) syndrome, which is a chronic multiorgan granulomatous inflammatory condition of unknown aetiology, which principally affects the eyes, auditory system, meninges and skin 14 . The common link between the ocular, cutaneous and central nervous system signs is a similar embryological development of pigment containing cells, which are the target of the granulomatous inflammation 14 . The mechanism that triggers the autoimmune reaction is unknown, but sensitisation to melanocytic antigens by means of cutaneous injury or possible viral infection has been postulated 15,16 . Experimental evidence suggests that VKH involves a T-lymphocyte mediated autoimmune process directed against an unknown antigen associated with melanocytes. Exposure of lymphocytes from human patients with VKH disease to peptides derived from the tyrosinase family of proteins led to significant proliferation of lymphocytes. The tyrosinase family of proteins are enzymes involved in melanin formation and are expressed specifically by melanocytes. Immunisation of these peptides into pigmented rats induced ocular and extraocular changes that highly resembled human VKH disease 17 . Canine UVD is similarly believed to be due to an immune-mediated reaction against melanocytes, but there is little evidence that demonstrates an underlying trigger factor, although both bacterial and fungal causes have been suggested 2,3,6,18 . In one study, histopathological examination of a young male Japanese Akita revealed sequestration of uveal melanocytes surrounded by large accumulations of inflammatory cells, in a very similar pattern to that presented in man, however the immunological basis for this inflammation has not been clearly identified in the veterinary literature 9. Histopathologically our canine patients exhibit a granulomatous panuveitis with prominent perivascular lymphoid aggregates and melanophages, whilst the anterior chamber often containing many lymphocytes and plasma cells. On examination of the posterior segment there are commonly retinal detachments, destruction of the retinal pigmented epithelium, subretinal neovascularisation and choroidal scarring and signs consistent with secondary glaucoma. Histopathology of the skin reveals interface dermatitis with a primary lichenoid pattern. Studies conducted in people suffering with VKH indicated that CD3 +† T cells constituted the majority of lymphocytes present in aqueous humour and cerebrospinal fluid (CSF) 19 . The percentage of CD4 + lymphocytes in uveitic aqueous humour and CSF was significantly higher than was present in the peripheral blood (p<0.001), and activated CD4 + and CD8 + cells were significantly more frequent in aqueous humour than in CSF and the peripheral circulation 19 . Fas †† antigen was also highly expressed by CD4 + cells in aqueous humour and there was a significantly higher proportion of Fas+ and memory cells in the aqueous humour than in the CSF or peripheral blood 19 . Histopathological analysis of cutaneous lesions in people with VKH revealed mononuclear cell infiltration of the slightly oedematous dermis, especially surrounding hair follicles and sweat glands 20 . Melanin-laden cells in the epidermis were partially lost, and the infiltrating mononuclear cells consisted primarily of T lymphocytes and a small number of B lymphocytes 20 . Most cells expressed HLA-DR (Human Leukocyte Antigen-DR), and CD4 + lymphocytes were dominant over CD8 + in a ratio of 3:1. The results suggest that cell-mediated immunity plays an important role in the pathogenesis of cutaneous lesions of humans with VKH 20 . The central nervous signs of human VKH are rarely seen in dogs, however a single Japanese Akita presenting with clinical central nervous system signs not explained by another disease process has been reported 6. One study described a single Siberian Husky with a sub-acute meningitis at necropsy that was similar to that found in humans with VKH 12 . Therefore, although canine patients cannot unequivocally be shown to have VKH syndrome, they may have a VKH-like syndrome. This syndrome in the dog has been named Uveodermatological syndrome (UVD). In veterinary studies conducted using immunohistochemistry several interesting findings have emerged. Examination of affected tissues from canine patients revealed that the skin lesions were mediated by a T Cell and macrophage response (T helper [Th] 1 immunity), whereas the ocular lesions were much more consistent with a B-cell and macrophage response (Th2 immunity)

† 1 CD3+,CD4+,CD79a are cluster of differentiation 3+, 4+ and 79a †† 2 Fast Kinase protein found on cell surface of most cells

23 In the medical literature an attempt has been made to determine the immunological factors associated with VKH. Experimental observations have demonstrated that tyrosinase peptides are immunogenic, and may be a candidate autoantigen in VKH 22 Later studies reported that lymphocytes from patients with VKH made strong proliferative responses when cultured with peptides derived from the tyrosinase family proteins 17 . Injection of these peptides into pigmented rats induced ocular and extraocular changes that resembled human VKH. These studies support the hypothesis that VKH involves an autoimmune response to the tyrosinase family proteins. Studies in people have shown that the presence of the major histocompatibility complex allele HLA-DRB-1 was associated with VKH syndrome 22 . This was further investigated in the Han Chinese using molecular genetic techniques and these studies found that HLA- DRB1*0405 and DRB1*15 were closely associated with the susceptibility to VKH syndrome. DRB1*0405 was probably the major susceptibility gene with DRB1*15 having a minor association. There was also a negative association between DRB1*14, DRB1*08 and the susceptibility to VKH syndrome, suggesting that there may be resistance genes 23 . In Korean patients with DRB1*0405 a reduction in visual acuity and increase in ocular complications was common, suggesting that HLA-DRB1*0405 itself or a haplotype including this allele, greatly increased the risk for developing VKH syndrome 24 . Although the canine MHC class II genes are now well defined 25 , there have been no studies of genetic associations with UVD in the Japanese Akita. The recent research in people may lead to some new areas for investigation in the susceptible canine population and may help to localise the immunological factors that are involved in this devastating canine disease.

REFERENCES 1. Asakura S, Takanashi K, Onishi T. Vogt-Koyanagi-Harada syndrome (uveitis diffusa acuta) in the dog. Japanese Journal of Veterinary Medicine 1977; 673 :445-55. 2. Bussanich MN, Rootman J, Dolman CL. Granulomatous pan uveitis and dermal depigmentation in dogs. Journal of the American Animal Hospital Association 1982; 18 :131-8. 3. Kern TJ, Walton DK, Riis RC, Manning TO, Laratta LJ, Dziezyc J. Uveitis associated with poliosis and vitiligo in 6 dogs. Journal of the American Veterinary Medical Association 1985; 187 :408-14. 4. Romatowski J. Uveodermatological syndrome in an Akita dog. Journal of the American Animal Hospital Association 1985; 21 :777-80. 5. Campbell KL, McLaughlin SA, Reynolds HA. Generalised leukoderma and poliosis following uveitis. Journal of the American Animal Hospital Association 1986; 22 :121-4. 6. Cottrell BD, Barnett KC. Haradas disease in the Japanese Akita. Journal of Small Animal Practice 1987; 28 :517-21. 7. Morgan R V Vogt-Koyanagi-Harada Syndrome in humans and dogs. Compendium of Small Animal Practice 1989; 11 :1211-8. 8. Vercelli A, Taraglio S. Canine Vogt-Koyanagi-Harada like syndrome in two Siberian Husky dogs. Veterinary Dermatology 1990; 1 151-8. 9. Lindley DM, Boosinger TR, Cox NR. Ocular histopathology of Vogt-Koyanagi-Harada like syndrome in an Akita dog. Veterinary Pathology 1990; 27 :294-6. 10. Collins BK, MacEwen EG, Dubielzig RR, Swanson JF. Idiopathic granulomatous disease with ocular adnexal and cutaneous involvement in a dog. Journal of the American Veterinary Medical Association 1992; 201 :313-6. 11. Herrera HD, Duchene AG. Uveodermatological syndrome (Vogt-Koyanagi-Harada-like syndrome) with generalized depigmentation in a Dachshund. Veterinary Ophthalmology 1998; 1:47-51. 12. Denerolle P, Tessier M, Molon-Noblot S. Nerve lesion in a Siberian Husky suffering from a uveodermatological syndrome. Pratique medicale et chirurgicale de l'animal de compagnie 2000; 35 :273-8.

24 13. Zavros N.S SM, Koutinas A.F, Komnenou A. Uveodermatological syndrome in an Akita dog. Australian Veterinary Practitioner 2001; 31 :27. 14. Read RW, Holland GN, Rao NA, Tabbara KF, Ohno S, Arellanes-Garcia L, Pivetti-Pezzi P, Tessler HH, Usui M. Revised diagnostic criteria for Vogt-Koyanagi-Harada disease: report of an international committee on nomenclature. American Journal of Ophthalmology 2001; 131 :647-52. 15. Rathinam SR, Namperumalsamy P, Nozik RA, Cunningham ET, Jr. Vogt-Koyanagi-Harada syndrome after cutaneous injury. Ophthalmology 1999; 106 :635-638. 16. Minoda H, Sakai J, Suigiura M. High incidence of Epstein-Barr virus replication in B lymphocytes in Vogt-Koyanagi-Harada disease. Nippon Ganka Gakkai Zasshi 1999; 103 :289-296. 17. Yamaki K, Gocho K, Hayakawa K, Kondo I, Sakuragi S. Tyrosinase family proteins are antigens specific to Vogt-Koyanagi-Harada disease. Journal of Immunology 2000; 165 :7323-9. 18. Murphy C J, Bellhorn RW, Thirkill C. Anti-retinal antibodies associated with Vogt-Koyanagi- Harada like syndrome in a dog. Journal of the American Animal Hospital Association 1991; 27 :399-402. 19. Ohta K, Yoshimura N. Expression of Fas antigen on helper T lymphocytes in Vogt-Koyanagi- Harada disease. Graefe’s Archives of Clinical and Experimental Ophthalmology 1998; 236 : 424-439. 20. Okada T, Sakamoto T, Ishibashi T, Inomata H. Vitiligo in Vogt-Koyanagi-Harada disease: immunohistological analysis of inflammatory site. Graefes, Archives of Clinical and Experimental Ophthalmology 1996; 234 :359-63. 21. Kobayashi H, Kokubo T, Takahashi M, Sato K, Miyokawa N, Kimura S, Kinouchi R, Katagiri M . Tyrosinase epitope recognized by an HLA-DR-restricted T-cell line from a Vogt-Koyanagi- Harada disease patient. Immunogenetics 1998; 47 :398-403. 22. Alaez C, del Pilar MoM, Arellanes L, Cano S, Perez-Luque E, Vazquez MN, Olivo A, Burguete A, Hernandez A, Pedroza M, Gorodezky C. Strong association of HLA class II sequences in Mexicans with Vogt-Koyanagi-Harada's disease. Hum Immunol 1999; 60 :875-82. 23. Zhang M, Qiu C, Hu T. [Association of HLA-DRB genes with Vogt-Koyanagi-Harada syndrome in a Chinese Han population]. Zhongguo Yi Xue Ke Xue Yuan Xue Bao 2000; 22 :36-40. 24. Kim MH, Seong MC, Kwak NH, Yoo JS, Huh W, Kim TG, Han H. Association of HLA with Vogt-Koyanagi-Harada syndrome in Koreans. American Journal of Ophthalmology 2000; 129 :173-7. 25. Kennedy LJ, Barnes A, Happ GM, Quinnell RJ, Bennett D, Angles JM, Day MJ, Carmichael N, Innes JF, Isherwood D, Carter SD, Thomson W, Ollier WER. Extensive interbreed, but minimal intrabreed, variation of DLA class II alleles and haplotypes in dogs. Tissue Antigens 2002; 59 : 194-204.

25 NOTES

26 IMMUNE-MEDIATED BLISTERING DISEASES Vanessa Schmidt

RCVS/Schering Plough Resident in Veterinary Dermatology, Small Animal Teaching Hospital, The University of Liverpool, Leahurst Campus, Chester High Rd, Neston, CH64 7TE

INTRODUCTION The main differential diagnoses of vesicles, bullae, erosions, ulcers and crusts affecting the oral cavity, mucocutaneous junctions, claws, pads and/or skin include: 1. Pemphigus – vulgaris (PV), paraneoplastic (PNP) 2. Pemphigoid – bullous (BP), mucocutaneous pyoderma(MCP), Linear IgA bullous dermatitis (LAD), epidermolysis bullosa aquista (EBA), congenital epidermolysis bullosa (EB) 3. Lupus Erythematosus – Bullous systemic lupus erythematosus (BSLE), Ulcerative cutaneous lupus erythematosus (UCLE), cutaneous lupus erythematosus (CLE) 4. Erythema multiforme (EM), Steven Johnson’s syndrome (SJS), toxic epidermal necrosis (TEN) complex 5. Epitheliotrophic lymphoma 6. Drug reaction 7. Ulcerative Stomatitis (if lesions are limited to the oral cavity) This presentation will summarise the immune-mediated diseases which encompass a diverse group of conditions associated with clefting either within the deep layers of the epidermis or at the dermo-epidermal junction with resultant blister formation. As the epidermis of dogs and cats is inherently thin, the blisters tend to be transient and quickly rupture leaving erosions, ulcers and crusts. The conditions can be summarised as follows: 1. Autoantibody targets desmosomes (intercellular bridges) in the basal epidermis resulting in suprabasilar clefting e.g. PV 2. Autoantibody targets a component of the basement membrane zone (BMZ) which results in sub-epidermal clefting e.g. BP, MMP, LAD, EBA 3. Mutations of the basement membrane molecules result in cleft formation e.g. Congenital EB 4. Keratinocyte necrosis results in a loss of adherence between the epidermis and dermis with a sub-epidermal cleft e.g. EM complex

PEMPHIGUS VULGARIS Pathogenesis PV is the rarest form of pemphigus and resembles human PV clinically, histopathologically and immunologically. Like Pemphigus foliaceus (PF), auto-antibodies (AAB) target the intercellular keratinocyte bridges, desmosomes. These form electron dense structures on the plasma membrane of adjacent keratinocytes. Desmosomes are comprised of extracellular transmembrane desmosomal cadherins (desmosgliens [Dsg] and desmocollins [Dsc]) and a set of intracellular plaque proteins which anchor to the immediate keratin filaments of the keratinocyte. Two adjacent desmosomes (and therefore cells) are attached by Dsg and Dsc, which exhibit very strong, calcium-dependant binding. Desmosomal cadherins consist of three types of desmogleins and desmocollins. The type of isomer expressed by the keratincytes depends on the location within the epidermis and the body location. Desmoglein 3 (Dsg3) is the main auto-antigen targeted in PV. It is preferentially expressed by the basal and suprabasal layers of the oral mucosa. Mucosal PV targets only Dsg3 while mucocutaneous PV targets Dsg3 and Dsg1. Dsg1 is highly expressed by superficial keratinocytes, particularly in the haired skin. It is also expressed at all levels of the epidermis on the dorsal muzzle, pinnae and foot pads. Lesions therefore preferentially present at sites of maximal antigen expression. Dsg1 has

27 recently been confirmed to be a minor auto-antigen in PF where acantholysis and cleft formation is more superficial. Disruption of Dsg3 results in acantholysis in the basal epidermis, leading to clefting between the stratum basale and stratum spinosum. Remnant basal cells are often left attached (via hemidesmosomes) to the basement membrane along the base of the cleft (the so-called ‘tombstone’ cells on histopathology). The exact pathomechanism of acantholysis is unknown but hypothesis includes a number of pathways:

• Direct interference in cadherin binding – although it has recently been shown that AAB to Dsg3 alone is insufficient to cause lesions. • Plakoglobin; intracellular plaque protein of the desmosome appears critical for lesion formation in mice. • Upregulation of P-cadherin (Calcium-dependant epidermal adhesion molecule) which occurs in auto-immune disease and congential acantholytic disorders in humans is suggested to be involved. • AAB induce activation and release of keratinocyte proteolytic enzyme (urokinase plasminogen) which converts plasminogen into plasmin and cleaves cadherin bonds. • Inactivation of cholinergic receptors, which control keratinocyte adhesion and motility, by AAB may result in disassembly of desmosomes. Re-activation can prevent, stop and reverse acantholysis in vitro. • Disruption of Dsg3 results in a lack of c-Myc (proto-oncogene) suppression (human and dog). c-Myc therefore causes continued proliferation, transformation and apoptosis. In the mouse model inhibition of c-Myc or a factor upstream from c-Myc inhibited acantholysis. In humans and dogs the disease is usually spontaneous. Paraneoplastic PV and drug-induced has been described in humans and are putative in the dog. Thiols and masked thiols (sulphur containing molecules) have been implicated.

Clinical findings PV has been reported in dogs, cats, horses, a llama and a pigtail macaque. In a recent meta- analysis of 52 dogs; GSD and collie were over-represented, the median age was six and males outnumbered females (3:2). No predilections have been found in cats. The clinical signs are more severe than in pemphigus foliaceus and are similar to sub-epidermal blistering diseases (see below) . The primary lesions are vesicles or bullae, which quickly rupture forming erosions, ulcers and crusts (on non-mucosal surfaces). Erythema may precede vesicles on the haired skin areas. The erosions and ulcers tend to enlarge and coalesce and may bleed easily leaving large haemorrhagic crusts. The Nikolsky sign may be present. Mucosal predominant PV commonly evolves to mucocutaneous PV possibly via epitope spreading. Affected sites include the oral cavity (tongue, palate and gingiva), concave pinnae, auditory orifices, the nasal planum, periocular areas, muco-cutaneous junctions (lips, genitalia, anus), nipples, glaborous and intertriginous skin and wear points. Erosive paronychia, onychomadesis and foot pad sloughing can occur. Most cases are of the generalised phenotype but localised variants have been reported to affect only the oral cavity, the nasal planum, the dorsal muzzle and the nasal planum, the claws and/or the nail beds or trunk. Other clinical signs include pain, lethargy, anorexia, pyrexia and halitosis. Secondary infection of the ulcers is common and severe systemic involvement and septicaemia can be fatal.

Histopathology The key histopathological finding is suprabasilar acantholysis with cleft formation above the basal cell layer. Remnant basal cells may remain attached to the basement membrane like a row of tombstones. Non-specific findings include erosion, ulceration and sero-cellular crusting. Inflammatory infiltrates are sparse in early lesions, but later lesions may exhibit neutrophil-rich exocytosis and perivascular to lichenoid inflammatory infiltrates. In some cases immunofluorescence (direct+/- indirect) +/- Elisa or immunoblotting studies are required to confirm the diagnosis.

28 Treatment The prognosis is extremely poor as it is very difficult to reach or maintain remission. Immunosuppressive doses of prednisolone with azathioprine or chlorambucil is the treatment of choice. Heparin (100IU/kg every 12 hours SC) had temporary benefit in a medically refractive case +/- prednisolone. The action of heparin is speculative and may be due to inhibition of intraepidermal proteolysis or by reducing the cytotoxic actions of lymphocytes/AAB.

SUB-EPIDERMAL BLISTERING DISEASES

Introduction Sub-epidermal blistering diseases are associated with auto-antibody production against components of the basement membrane zone (BMZ). This leads to the loss of adhesion between basal keratinocytes and the dermis with resultant cleft and bulla formation. The bulla quickly ruptures to leave ulcers and crusts. These conditions are clinically and histopathologically rather similar and many can only be differentiated by identifying the precise target molecule, which may not be easy in practice. They are, furthermore, very similar to congenital conditions associated with mutations in basement membrane molecules that also result in clefting e.g. junctional or dystrophic EB. However it should be easy to differentiate hereditary from the acquired forms as the congenital conditions occur either at birth or at less than two months of age. Immunologic studies (immunofluorescence and immunohistochemistry) for detection of in situ and circulation AAB, immunoblotting, ELISA and other studies to characterise the target antigen are required to confirm the diagnosis and differentiate the diseases.

Pathogenesis The dermo-epidermal junction (BMZ) is a complex structure comprising the basal cell plasma membrane (hemidesmosomes), lamina lucida, lamina densa and sublamina densa (anchoring fibrils). The individual components are not visible on routine histopathology. With electron microscopes, hemidesmosomes form electron-dense lines on the basal plasma membrane and are attached to intracellular intermediate keratin filaments. Beneath the lamina densa are anchoring fibrils which attach to dermal collagens. Hemidesmosomal proteins include: plectin, bullous pemphigoid antigen 1 (BPAG1; 230 kd), bullous pemphigoid antigen 2 (BPAG; 180 kd) and 6 4 integrin. BPAG2 and 6 4 integrin project into the lamina lucida where they bind to thαe aβnchoring filaments of laαmiβnin and uncein. Laminin and uncein in turn project into the lamina densa, which is a mesh of Type IV collagen, and bind to sub-basal lamina type VII collagen (anchoring fibrils). Type VII collagen binds to types I, III and V dermal collagens. (Figure below).

© Mataleena Parikka, Department of Diagnostics and Oral Medicine, University of Oulu, Oulu, Finland

29 Specific proteins associated with immune-mediated blistering diseases in animals include: • Bullous pemphigoid (dog and cat) - NC16A ectodomain of BPAG2 (collagen XVII) • Mucous membrane pemphigoid (dog and cat) - different epitopes of BPAG2 and laminin 5 • Linear IgA bullous dermatosis (dog) - LAD 1 (soluble collagen XVII fragment) • Epidermolysis bullosa acquisita (dog) - noncollagenous (NC1) domain of type VII collagen In humans: • Bullous pemphigoid - BPAG1 (BP230), BPAG2 (collagen XVII) • Mucous membrane pemphigoid - BPAG2 (distal extracellular domain or NC16A), alpha subunit of laminin 5 (laminin 6), integrin subunit beta-4, type VII collagen. • Linear IgA bullous dermatosis - 120-kDa extracellular segment of type XVII collagen, 45-kDa protein of type VII collagen, un-identified 285-kDa protein above LL • Epidermolysis bullosa acquisita - Type VII Collagen (four predominant antigenic epitopes within the NC1 domain) Common clinical signs and features The clinical signs of this group of diseases tend to be fairly similar and it can be very difficult to distinguish them without special techniques. Most of these conditions affecting the basement membrane were originally described as bullous pemphigoid and it is only recently that the other conditions have been recognised and characterised in veterinary dermatology. MMP has therefore become the most common auto-immune disease of the BMZ of the dog and cat. The primary lesions are fluid or blood filled vesicles or bullae, which rapidly rupture forming multifocal ulcers. Crusts are usually present on haired skin. Different from PV, the clefts form subepidermally, therefore the vesicles and bullae are less fragile and may be seen more commonly, particularly in protected sites, and the ulcers tend to remain the same diameter as the bullae which have ruptured. The typically affected sites include muco-cutaneous junctions, oral cavity, face, nipples, and intertriginous skin and wear points subject to friction. Other clinical signs can include pain, lethargy, anorexia, pyrexia, halitosis and secondary infection. Severe systemic involvement and septicaemia can be fatal. Ulcerated lesions may heal with scarring. Bullous pemphigoid is a very rare condition. The typical clinical course of true BP seems to be chronic but relatively mild and there are usually no systemic signs associated with blistering episodes. Footpads are rarely affected in contrast to EBA and oral lesions are less common than in PV. The ulcers do not coalesce or spread as they do in PV. Signalment has been identified. Linear IgA bullous dermatosis is a very rare disease that is clinically very similar to bullous pemphigoid. Inflammation is minimal. Mucous membrane pemphigoid (cicatricial pemphigoid) is a rare condition that has marked mucocutaneous predilection. Commonly affected sites include the oral cavity, nasal planum, perinasal skin, periorbital region, concave pinnae, genitalia and anus. Conjunctival and footpad lesions are uncommon. AAB are more heterogeneous than BP. GSD may be more predisposed, the median age is five years and males outnumber females by one third. Epidermolysis bullosa acquisita is a rare, recently recognised disease affecting the oral cavity, mucocutanoeous junctions, footpads, nasal planum, concave pinnae and glabrous skin (axillae and abdomen). It initially presents with erythematous macules and urticarial plaques that rapidly evolve into tense vesicles (may be blood filled) which erode and ulcerate. Skin sloughs from the oral cavity (halitosis, hypersalivation and anorexia), mucocutaneous junctions and frictional skin. The phenotype can be generalised or localised. Young Great Danes appear to be predisposed. This condition is more likely to have footpad involvement and systemic signs than BP and MMP.

30 Histopathololgy The sub-epidermal blistering diseases result in vesicle and cleft formation beneath the basal cell layer of the epidermis without acantholysis (as the keratinocytes are unaffected). Ulcers predominate once the epidermis has separated. The type of inflammation varies: eosinophils are common with bullous pemphigoid, neutrophils with epidermolysis bullosa acquisita and mucous membrane pemphigoid is relatively non-inflammatory or lichenoid. Chronic MMP lesions with lichenoid dermatitis only may not be easily differentiated from mucocutaneous pyoderma.

Immunological studies Antigen immunomapping using collagen IV-specific monoclonal AB (major component of LD) will demonstrate the vesiculation above or below the LD. Direct immunofluorescence detects immunoglobulin deposition (IgG with BP, MM, EBA and IgA with LAD). Indirect immunofluorescence to detect circulating antibodies on salt split skin (at the LL) can determine if the cleft is to the epidermal or dermal side of the LL.

Management and prognosis The prognosis, although not yet established for these diseases due to small numbers, would appear to be guarded. Treatment usually involves immunosuppressive doses of prednisolone with azathioprine or chlorambucil for severe cases, while topical glucocorticoids may be sufficient for mild cases of BP. Tetracycline and erythromycin have been beneficial in humans with BP possibly by inhibiting neutrophil chemotaxis, increasing dermo-epidermal cohesion and inhibiting proteases. UV light avoidance is recommended.

ERYTHEMA MULTIFORME COMPLEX

Introduction Erythema multiforme (EM) complex is a group of rare, immune-mediated dermatoses with varied clinical signs. The classification of the complex is controversial, but a recent study sub-divided the group into the progressively more severe variants: EM minor, EM major, Stevens-Johnson syndrome (SJS), SJS-TEN (SJS-toxic epidermal necrolysis) overlap syndrome and TEN. Other authors reported that keratinocyte apoptosis is a feature of EM but not SJS- TEN, and concluded that they should be regarded as separate conditions. Another theory is that apoptosis in SJS-TEN is acute and massive leading to widespread epidermal necrosis; whilst in EM it is more chronic and progressive

Proposed veterinary classification of the EM complex of diseases:

EM minor EM major SJS SJS-TEN TEN Polycyclic to target lesions YYNNN Mucosal surfaces involved N (or 1) >1 >1 >1 >1 Erythematous or purpuric macules/ <50% <50% >50% >50% >50% patches (%BSA) Epidermal ulceration (%BSA) <10% <10% <10% 10-30% >30%

31 In human medicine classification is based on clinical, histopathological and aetiological features:

Clinical signs Histopathology Aetiology EM erythematous target apoptotic and infectious or lesions inflammatory inflammatory EM minor no mucosal lesions EM major mucosal lesions HSV-EM mucosal lesions viral SJS-TEN few or no target lesions necrotic and sparsely drug induced cellular

This classification is not universally accepted, however, and many overlap and difficult to classify patients are recognised.

Pathogenesis

EM The pathogenesis is poorly understood and multiple aetiologies/triggers have been implicated. It is currently thought to be a host specific cell-mediated hypersensitivity reaction directed towards various antigens: • Infections (distemper, herpes) • Systemic disease (connective tissue disease) • Drugs (potentiated sulfonamides, penicillins, cephalosporins) • Food/food additives • Neoplasia (splenic sarcoma – 1 report) • Chemicals/UV light • Idiopathic In dogs, immunohistochemical similarities have been shown with graft vs host disease. The keratinocytes may be altered (by drugs or infection etc.) which stimulates a pathway of events resulting in apoptosis. Expression of intercellular adhesion molecule 1 (ICAM-1), class II major histocompatibility complex molecules, CD44 and CD1a by keratinocytes recruits, activates and tethers T-cells in the epidermis. Intraepithelial T-cells signals are thought to be responsible for apoptosis.

SJS-TEN SJS, SJS-TEN overlap and TEN are more commonly associated with drug eruptions. Again the pathogenesis is not completely understood, but it is thought to involve a specific immune-mediated assault on keratinocytes causing widespread, confluent keratinocyte apoptosis and epidermal necrosis. SJS-TEN, has been linked to certain phenotypes in humans that exhibit abnormal drug metabolism resulting in reactive metabolites. Hypothesis includes: • Defective epidermal detoxification of drug by-products • CD8 + cytotoxic cells – apoptosis of keratinocytes in humans • Perforin – may play a role in the massive apoptosis of keratinocytes. It is contained in cytotoxic T-cells and natural killer cells • Calprotecin (a calcium binding protein) – increases of TNF alpha from keratinocytes affected by toxic drug metabolites may cause keratinocyte apoptosis in the absence of inflammatory cells • TNF alpha (from keratinocytes/macrophages) may play a role in direct apoptosis of keratinocytes and/or attract cytotoxic effector cells. Massive over-expression in epidermis of SJS-TEN (humans) but only minute amounts in EM

32 • Fas-Fas ligand – upregulation of cell surface death receptor (CD95) and ligation by T-cell expressed ligand • Massive toxic epidermal necrosis – toxic as opposed to immune-mediated

Clinical features

EM Clinical signs in EM are variable and usually symmetrical. The lesions include: erythematous macules, papules, plaques, wheals, scaling and crusts, vesicles, bullae and ulcers and are often in annular, arcuate, or polycyclic shapes. Target lesions consist of a flat to raised erythematous central disk and outer ring, separated by a zone of pale skin, but are not common in animals. Some dogs present with marked scaling and crusting overlying the lesions. The groin, axillae, muco-cutaneous junctions, oral cavity, pinnae and footpads are predisposed in dogs and the muco-cutaneous junctions and the trunk in cats. Mucosal lesions are usually vesiculo-bullous and quickly rupture to form ulcers. The Nikolsky sign, pitting distal limb oedema and pain may be present in some cases but pruritus is rare. Clinical signs associated with an underlying disease may be present. EM, particularly in humans, is normally an acute self-limiting condition, but in idiopathic cases can be recurrent and chronic.

SJS-TEN Polycyclic and target lesions are unusual in SJS-TEN, which present with an erythematous macular dermatitis, and focal to widespread muco-cutaneous vesicles, epithelial detachment and ulceration. The skin lesions can be painful, especially with widespread necrosis and ulceration, and Nikolsky’s sign may be present. Other clinical signs include loss of nails, corneal ulceration and ulcerative otitis. Internal involvement can include mild to severe loss of mucosae, renal failure, hepatopathy and blood dyscrasias. Some dogs may remain bright and well, but those with more severe ulceration become pyrexic and depressed. Fluid and electrolyte losses, and secondary infections can be life threatening. SJS-TEN usually has an acute onset and is one of the few genuine dermatological emergencies. There may, however, be a vague malaise during the prodromal phase. This generally lasts 1-2 weeks, presumably whilst drug sensitisation develops, before acute onset of the muco- cutaneous lesions.

Diagnosis Differential diagnoses include: • Urticaria • Thermal burns • Deep infections • Pemphigus/Pemphigoid • SLE • Vasculitis • EL • Cutaneous drug reaction The history and clinical signs are highly suggestive, and the diagnosis can be confirmed by excluding other differentials and histopathology of early lesions.

Histopathology Histopathology may not be able to differentiate between EM and SJS-TEN but generally EM is more inflammatory and less necrotic.

EM Erythematous, polycyclic and target lesions are characterised by single cell keratinocyte apoptosis and mononuclear cell satellitosis at all levels of the epidermis. When the skin is intact there may be mild to moderate acanthosis and mild to severe orthokeratotic hyperkeratosis. Lymphocytic-plasmacytic cell-rich interface dermatitis is common and may also occur with basal cell degeneration, mild to moderate superficial interstitial or more intense lichenoid, mononuclear cell dermal infiltrate. 33 SJS-TEN More severe lesions are associated with hydropic basal cell degeneration, full-thickness necrosis of the epidermis with dermo-epidermal separation (above the basement membrane), formation of vesicles and ulceration. Usually cell-poor interface dermatitis is present.

Management and prognosis EM can be a challenging condition to manage. The prognosis is better if the inciting cause can be identified and removed, which may require a diet trial. Some cases of EM spontaneously resolve or wax and wane, but progression to SJS-TEN does not appear to occur. The prognosis for SJS-TEN is poor, with mortality rates approaching 50%. Surviving patients may suffer extensive scarring. SJS-TEN is usually a single episode, unless there is re-exposure to the inciting drug.

EM The role of glucocorticoids is controversial; some authors advocate their use, while others consider them harmful. Large doses of prednisolone with or without azathioprine have been used in dogs with severe idiopathic disease. There are also reports of response to ciclosporin (5mg/kg once daily), retinoids or pentoxifylline (10-15mg/kg bid-tid). Long term maintenance treatment may be necessary in idiopathic cases but spontaneous remission has occurred.

SJS-TEN Identify and remove underlying cause if possible. Glucocorticoids may again increase the risk of sepsis and in humans were associated with increased morbidity and mortality. Severe cases with widespread ulceration should receive intravenous fluid therapy to combat dehydration and shock. The ulcers should be cleaned and protected with silver sulphadiazine cream, with activated silver and other protective dressings to encourage healing and prevent infection. Consideration should also be given to analgesia and antibiotics to prevent sepsis, although this must be weighed against the risk of potentiating a drug reaction. Intravenous therapy with human immunoglobulin (ivHIG) (0.5-1.5g/kg IV over 6-12 hours) has been helpful in few cases of SJS and TEN in dogs and cats. ivHIG is widely used to treat similar conditions in human medicine. It is thought to break the cycle of ongoing keratinocyte apoptosis in EM, SJS and TEN by blocking FAS/FAS ligand (CD95/CD95L) interactions. ivHIG also binds to IgG Fc receptors (which inhibits cell activation and modulates cytokine synthesis and release), neutralises AAB and immune complexes, blocks complement activity, is antimicrobial and increases colloid osmotic pressure. Treatment may also, therefore, limit ongoing inflammation, secondary infection, and fluid and electrolyte losses. Because these are foreign proteins repeated treatment of animals is not recommended due to the risk of an anaphylactic reaction. Other potential side effects include pyrexia, malaise, joint pain, nausea, vomiting and other vasomotor signs, renal failure, thrombo-embolism, aseptic meningitis, fluid overload, pruritus, urticaria, vasculitis and petechiae.

34 FACIAL DERMATOSES IN DOMESTIC ANIMALS: CUTANEOUS LUPUS ERYTHEMATOSUS AND MUCO- CUTANEOUS PYODERMA Filippo De Bellis Dept. Veterinary Clinical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield AL9 7TA

CUTANEOUS LUPUS ERYTHEMATOSUS

Introduction Skin diseases with similarities to human Lupus Erythematosus (LE) have been reported in dogs, cats and horses. Cutaneous manifestations of lupus diseases have a diverse clinical presentation but a common histopathological pattern that includes lymphoplasmacytic interface dermatitis with apoptosis of the basal keratinocytes. The classification of these conditions is controversial. Classically lupus erythematosus (LE) is divided into a multi-systemic disease (systemic lupus erythematosus – SLE) and a cutaneous disease (“discoid lupus erythematosus” or cutaneous lupus erythematosus – CLE), which may or may not be present with the former. In human medicine the cutaneous manifestations of lupus are further classified as acute cutaneous lupus erythematosus (ACLE), sub-acute cutaneous lupus erythematosus (SCLE) and chronic cutaneous lupus erythematosus (CCLE), the latter known also as discoid lupus erythematosus (DLE)¹. In canine medicine the most common cutaneous form has been historically named, using the human terminology, DLE ²; however in this article the term nasal cutaneous lupus erythematosus (NCLE) will be used. Other forms may include Exfoliative Cutaneous Lupus Erythematosus of the German Short-Haired Pointer (ECLE)³ and Vesicular Cutaneous Lupus Erythematosus of the Shetland sheepdog and Collie (VCLE) 4, 5 . This article will cover the NCLE.

Pathogenesis The pathogenesis of this disease is poorly understood, and a relationship or progression to canine systemic lupus erythematosus has not been reported 2. According to Yager et al 6 the pathogenesis of diseases with lymphoplasmacytic interface dermatitis is thought to represent an immune-mediated attack upon altered keratinocytes by cytotoxic T lymphocytes. However, there are differences in the underlying immune mechanisms of NCLE compared to SLE as, in contrast to SLE, antinuclear antibodies are normally not found in NCLE 7. Moreover, in contrast to helper T-cell predominated human DLE, many plasma cells are found in the dog suggesting an important role for antibodies in the pathogenesis of the canine counterpart 2. The role of environmental factors is also considered important, as sun exposure aggravates the clinical signs in approximately 50% of cases 2 and therefore it is considered at least photo-aggravated if not photo-induced 7.

Signalment No sex and age predilections have been reported. Breed predilection has been reported for Collies, Shetland sheepdogs, German Shepherds and Siberian huskies 8. Clinical signs • Dog. The lesions are mainly restricted to the face 9 and are characterised initially by depigmentation, erythema, scaling and loss of the normal cobblestone architecture of the planum nasale, with involvement of the junction with haired skin and of the alar folds in a symmetrical distribution pattern. With chronicity the lesions may become more extensive and evolve in alopecia, crusting, erosions and ulcerations. Less commonly the periorbital regions, the pinnae, the distal limbs and the genitalia may be involved 2. Cases of erosive dermatitis affecting the anal and peri-anal region have also been reported 10,11 . Rare cases of squamous cell carcinoma arising from lesions of NCLE have been reported 12 .

35 • Cat. This condition has been rarely reported in cats 13 , with lesions consisting of alopecia, erythema, scaling and crusting involving face and pinnae. • Horse. Skin lesions begin on the face (lip, nostrils and periocular region) with symmetrical areas of erythema, scaling and alopecia and occasional presence of crusting, erosions and leukotrichia 14 . Some horses develop lesions on pinnae, neck, genitalia, perianal region 14 .

Differential diagnoses The differential list for NCLE might include various diseases with involvement of the planum nasale: • Pemphigus foliaceus (PF) – this also affects haired skin on the face and rest of the body. • Pemphigus erythematosus (PE) – this is considered to be an overlap condition between PF and NCLE and therefore differentiation may be difficult. • ECLE – this normally tends to be generalized and is reported only in German short-haired Pointers. • Mucous membrane pemphigoid – in this condition the mucocutaneous junctions are markedly involved. • Dermatomyositis – this normally tends to be generalized and planum nasale involvement may be absent. • Drug eruption – there should be association with a history of drug exposure. • Mucocutaneous pyoderma – in this case the clinical features can be confusing and assessment should be based on the response to antibiotic treatment. • SLE – there should be systemic disease. • Cutaneous epitheliotrophic lymphoma – this normally tends to be generalized. • Leishmaniasis – rare in the UK, history important (e.g. travelling abroad). • Vitiligo. • Solar vasculopathy – this can co-exist with NCLE and the two diseases may complicate each other. • Uveodermatologic syndrome – concurrent uveitis is a prominent consistent feature. • Hereditary nasal parakeratosis of the Labrador retriever – this occurs at young age and ablation of the normal cobble-stone structure may occur at a later stage with severe lesions; there is breed predisposition. • Idiopathic nasal or nasodigital hyperkeratosis – this does not alter the normal cobble- stone structure of the planum nasale. • Deep mycoses with involvement of the planum nasale. • Nasal aspergillosis. • Contact dermatitis. • Trauma – there should be a history of acute onset.

Diagnosis Diagnosis is made based on the breed, age at onset, ruling out other possible causes, dermatohistopathology and response to treatment. Dermatohistopathology of NCLE usually reveals lymphocyte-rich interface dermatitis. However, this infiltrate can be lymphoplasmacytic and in some cases mainly plasmacytic, especially in chronic lesions 15 . Basal cell apoptosis and vacuolar degeneration is considered an important feature of this condition, often with marked pigmentary incontinence, lymphocytic exocytosis and focal basement membrane thickening 6. Other features may include moderate acanthosis and epidermal atrophy 7 and increased intraepithelial and intradermal mucin deposition 15 . Direct immunofluorescence and immunohistochemistry shows deposition of immunoglobulin, complement or both at the basement membrane zone 2. A case with demonstrated circulating

36 antibodies and the basement membrane zone has been reported 16 . The histopathological differential diagnoses of NCLE include: • SLE – this sometimes can be indistinguishable and requires clinical differentiation. • ECLE – clinical differentiation is required. • VCLE – clinical differentiation is required. • Erythema multiforme – in this case the apoptosis is generally seen at all level of the epidermis and the satellitosis is more prominent. • Early patch and plaque stage lesions of cutaneous epitheliotropic lymphoma – in this case the intraepithelial lymphocytic infiltration tends to be more pronounced. • Mucocutaneous pyoderma – this is likely to represent the most confusing differential diagnosis not only clinically but also histopathologically. Chronic cases of NCLE with inflammation of the mucocutaneous junctions and predominance of plasmacytic infiltrate manifesting as a band-like superficial dermal infiltrate may mimic the features of mucocutaneous pyoderma. Additionally, although vacuolar degeneration and apoptosis of the basal cells are not considered typical features of mucocutaneous pyoderma, these may be lacking or subtle in chronic lesions of NCLE. In a recent retrospective study 17 the findings showed that these two conditions cannot be distinguished based purely on the histopathological features. • Uveodermatologic syndrome – in this case there is a more intense presence of macrophages in the dermal infiltrate with presence of melanophages, in contrast to NCLE where clumping of melanin is commonly seen. Clinical differentiation may be required.

Clinical management The prognosis for affected dogs is generally good but lifelong therapy may be required 2. Given the usually mild clinical signs, an aggressive immunosuppressive therapy is rarely indicated. Mild cases may be controlled with sun blockers and avoidance measures. This is recommended in all cases. Topical glucocorticoids (e.g. betametasone) can be initially used twice daily and after remission as needed 2. Topical treatment with tacrolimus led to satisfactory results in a study where 10 cases of NCLE and 2 cases of PE were treated; 8/10 dogs with NCLE and both PE cases improved and in 6/8 NCLE cases no other medications were used 18 . Tacrolimus is not licensed for use in animals. The combination of oral tetracycline and niacinamide has been used with variable success. In a study with 20 dogs affected by NCLE, 8 had excellent response (more than 90% resolution of the clinical signs and no other treatment needed), 6 had good response (50 to 90% resolution of clinical signs and if adjunctive prednisolone was needed, a dose of less than 0.5 mg/kg q 48 h was adequate), 2 had poor response (less than 50% resolution of clinical signs), and 4 had no response 19 . The dosage recommendations are 500 mg of each drug every 8 hours for dogs weighing over 10 kg and 250 mg at the same frequency for dogs weighing less than 10 kg. Systemic vitamin E and essential fatty acids supplementations have also been successfully used; in a study 7/16 dogs were controlled with vitamin E alone 8. In refractory cases oral prednisolone (1-2 mg/kg once daily for induction and tapered to effect) may be used.

MUCOCUTANEOUS PYODERMA

Introduction. Mucocutaneous pyoderma (MCP) is relatively uncommon syndrome that affects primarily the lips and perioral skin of the dog. 20 . This is a controversial condition as it shares many clinical and histological features with NCLE but is responsive to antibacterial therapy.

37 Pathogenesis The information about the aetiology and pathogenesis of MCP in the literature is sparse, and although the response to antibacterial treatment supports a bacterial aetiology, the frequent relapses are suggestive of a possible underlying immune-mediated pathomechanism.

Signalment No age or sex predilections have been reported. German Shepherd Dogs and their cross seem to be over represented 20,21 .

Clinical signs Lesions include erythema, swelling and crusting affecting mainly the lips and perioral skin; affected lips may become uniformly swollen and depigmentation may occur with chronicity 15 . Severe lesions may show ulcerations and pain and pruritus may be present. Similar lesions may affect the planum nasale (with presence of fissuring on one or both nares), prepuce, perianal and perivulvar region 20 . In a case-series of three dogs affected by MCP ulcerative lesions with clinical and histopathological features similar to those of MCP were observed on the inguinal and axillary regions of two dogs 21 . Differential diagnoses • NCLE – early lesions may be similar but the swelling of the lips is not consistent with this condition. • Lip fold intertrigo – this involves only the intertriginous area of the lips. • Zinc-responsive dermatosis – lesions usually involves the periorbital skin in a symmetrical fashion. • Erythema multiforme - ulcerative lesions localised mainly on the lips may mimic those of MCP. • Drug eruption – there should be association with a history of drug exposure. • Cutaneous epitheliotrophic lymphoma – this normally tends to be generalised. • Mucocutaneous candidiasis – rare, differentiation requires cytology and culture.

Diagnosis The diagnosis of MCP is based on clinical features, dermatohistopathology and response to antibacterial treatment. Dermatohistopathology usually reveals a dense band-like superficial dermal infiltrate composed predominantly of plasmacytes, mixed with lymphocytes, neutrophils and macrophages. Contrary to NCLE, the dermal-epidermal interface is not obscured. Other features include epidermal hyperplasia with lymphocytic exocytosis and variable degree of spongiosis and mild to severe pigmentary incontinence; variable serocellullar crusting is observed in lesions complicated by self trauma, erosions or ulcerations 15 . The histopathological features of MCP are not specific, differential diagnoses include: • Chronic inflammation of the mucocutaneous junctions • Intertrigo – when located near the mucocutaneous junctions can be indistinguishable • NCLE – see discussion above Given the non specific nature of these histopathological features, according to Lee Gross et al 15 , a diagnosis of mucocutaneous pyoderma may be applied inappropriately by pathologists.

Clinical management The condition responds to topical or systemic antibacterial therapy. For topical therapy the areas should be treated daily for two weeks and then once to twice weekly 22 , using a suitable antibacterial shampoo (benzoyl peroxide, chlorhexidine 2%) or gel/ointment formulations (fusidic acid or mupirocin, with the latter to be reserved for MRSA infections). Severe cases require systemic treatment for at least 3 to 4 weeks, based on the cytological findings and eventually on bacteriology culture and sensitivity. MCP is commonly reported as a relapsing condition 20 . In a case series report 21 long term management of MCP was successfully obtained with a pulsed antibiotic regimen.

38 In a retrospective study comparing the histopathological features and response to treatment in 27 cases of nasal pathology (mainly German shepherd dogs) attributable to NCLE or MCP, a treatment follow up was available in 15 cases. There were 4/15 cases that responded to antibiotic treatment alone and 9/15 that required antinflammatory treatment for prolonged remission; these were histopathologically indistinguishable 17 . At the Swedish Veterinary Dermatology Study Group meeting in March 2007, the consensus on treatment was to use antimicrobials for at least three weeks, then add anti-inflammatory or immunomodulator medications if needed (J. Rest, personal communication).

REFERENCES 1. Costner MI, Sontheimer RD. Lupus Erythematosus Chapter 171, 1677-1693 in: Freedberg I.M, Eisen AZ, Wolff K at al., Dermatology in general medicine. 6th ed.: McGraw-Hill Medical Publishing Division, New York 2003. 2. Scott DW, Miller WH, Griffin CE: Immune – Mediated Disorders Chapter 9, 667 –779 in: Small Animal Dermatology 6th Edition WB Saunders Company, Philadelphia 2001. 3. Bryden SL, White SD, Dunston SM, Burrows AK, And Olivry T. Clinical, histopathological and immunological characteristic of exfoliative lupus erythematosus in 25 German short- haired pointers. Veterinary Dermatology 2005; 16 : 239-252. 4. Jackson AH and Olivry T. Ulcerative dermatosis of the Shetland sheepdog and rough collie may represent a novel vesicular variant of cutaneous lupus erythematosus. Veterinary Dermatology 2001; 12 : 19-27. 5. Jackson AH, Olivry T, Berget F, Dunston S.M, Bennefont C, and Chabanne L. Immunopathology of vesicular cutaneous lupus erythematosus in the rough collie and Shetland sheepdog: a canine homologue of subacute cutaneous lupus erythematosus in human. Veterinary Dermatology 2004; 15: 230-239. 6. Yager JA, Wilkock BP. Interface Dermatitis Chapter 5, 85 –106 in: Colour Atlas and Text of Surgical Pathology of the Dog and Cat, Volume 1: Dermatopathology and Skin Tumors Mosby-Years Book, London 1994. 7. Lee Gross T, Irkhe PJ, Walder J, Affolter VK. Interface diseases of the dermal-epidermal junction Chapter 3, 52-56 in: Skin diseases of the dog and cat. Clinical and histopathological diagnosis 2nd edition Blackwell Science Ltd, Oxford 2005. 8. Scott DW, Walton DK, Manning TO, Smith CA, and Lewis RM. Canine Lupus Erythematosus. Journal of the American Animal Hospital Association 1983; 19 : 481-488. 9. Griffin CE, Stannard AA, Ihrke PJ Ardans AA Cello RM, and Bjorlinget DR. Canine discoid lupus erythematosus. Veterinary Immunology and Immunopathology 1979; 1: 79-87. 10. Schrauwen E, Junius G, Swinnen C, And Maenhout T. Dyschezia in dogs with discrete erosive anal disease and histological lesions suggestive of mucocutaneous lupus erythematosus. Veterinary Record 2004; 154 : 752–754. 11. Gerhauser I, Strothmann-Luersen A, And Baumgartner W. A case of interface perianal dermatitis in a dog: is this an unusual manifestation of lupus erythematosus? V eterinary Pathology 2006; 43 : 761-764. 12. Scott DW, Miller WH. Squamous cell carcinoma arising in chronic discoid lupus erythematosus nasal lesions in two German Shepherd Dogs. Veterinary Dermatology 1995; 6: 99-104. 13. Willemse T. and Koeman JP. Discoid lupus erythematosus in cats. Veterinary Dermatology 1989; 1(1) : 19-24. 14. Scott DW, Miller WH. Immune – Mediated Disorders Chapter 9, 475 –547 in: Equine Dermatology WB Saunders Company, Philadelphia 2003.

39 15. Lee Gross T, Irkhe PJ, Walder J, Affolter VK. Lichenoid diseases of the dermis Chapter 11, 261-271 in: Skin diseases of the dog and cat. Clinical and histopathological diagnosis 2nd edition Blackwell Science Ltd, Oxford 2005. 16. Iwasaki T, Shimitzu M, Obata H, Yanai T, Kitagawa H. and Sasaki Y. A canine case of discoid lupus erythematosus with circulating antoantibodies. Journal of Veterinary Medical Sciences 1995; 57 : 1097-1099. 17. Wielmelt SP, Goldschmidt MH, Greek JS, Jeffers JG, Wielmelt AP and Mauldin (EA). A retrospective study comparing the histopathological features and response to treatment in two nasal canine dermatoses, DLE and MCP. Veterinary Dermatology 2004; 15(6) : 341-348. 18. Griffies JD, Mendelshon CL, Rosenkrantz WS, Muse R, Boord MJ, and Griffin (CE): Topical 0.1% tacrolimus for the treatment of discoid lupus erythematosus and pemphigus erythematosus. Journal of the American Animal Hospital Association 2004; 40 : 29-41. 19. White SD, Rosychuk RAW, Reike SI, and Paradise M. Use of tetracycline and niacinamide for treatment of autoimmune skin disease in 31 dogs. Journal of the American Veterinary Medical Association 1992; 200 910 ): 1497-1500. 20. Irkhe PJ, And Lee Gross TL. Canine mucocutaneous pyoderma. Section 7 Dermatologic diseases, 571-655 in: Kirk’s Current Veterinary Therapy XII (edition JD Bonagura) WB Saunders Company, Philadelphia 1995. 21. Basset RJ, Burton GG, and Robson DC. Antibiotic responsive ulcerative dermatoses in German Shepherd Dogs with mucocutaneous pyoderma. Australian Veterinary Journal 2004; 82 : 485-489. 22. Scott DW, Miller WH, Griffin CE. Bacterial Skin Diseases Chapter 4, 274 –335 in: Small Animal Dermatology 6th Edition WB Saunders Company, Philadelphia 2001.

40 COMMON INFECTIOUS DISEASES OF THE FEET IN SHEEP AND CATTLE Agnes Winter BVSc, PhD, DSHP, DipECSRHM, FRAgS, MRCVS University of Liverpool, Leahurst Campus, Neston, CH64 7TE

Lameness is a very common and serious welfare issue in sheep and cattle (particularly dairy cows) which also has significant economic consequences for the flock or herd owner. In both species, diseases involving bacterial infection are very common and can affect a large proportion of the flock or herd.

Sheep There is a tendency for people unacquainted with sheep’s feet to assume that all lameness is due to footrot but there is actually a variety of causes and, in dealing with lameness on a flock basis, it is important to establish a diagnosis based on examination of a representative group of animals. It should also be remembered that more than one condition may be present. The main diagnostic features, treatment and control of common causes of foot lameness have been described by Winter (2004 a, and b; 2005). The three most common diseases seen on a flock basis are interdigital dermatitis (scald), footrot and contagious ovine digital dermatitis (CODD). Whilst the lesions of each and the associated microorganisms can be simplistically differentiated as described below, in reality the microbiology is much less clear. This has been demonstrated by Moore et al (2005a and b) and should be borne in mind in any detailed study. Additionally there may be uncertainty about the diagnosis in some individual animals but examination of a number of the group should reveal characteristic lesions on which a firm diagnosis can be based. Other common diseases such as white line disease, toe granuloma and septic arthritis of the pedal joint are often misdiagnosed by farmers as footrot. Three important sheep diseases seen on a flock scale Interdigital dermatitis (scald) This is a common cause of lameness in growing lambs but is also seen in adults. It is caused by the environmental organism, Fusobacterium necrophorum, which invades damp or damaged skin of the interdigital space causing inflammation. Wet, rapidly growing grass is a common predisposing factor although dirty bedding and any other environmental factor leading to devitalisation of the interdigital skin can precipitate the condition. Clinically the skin appears slightly swollen, moist and grey or reddened with loss of hair. There is no involvement or under-running of horn. In the absence of footrot infection in a flock, interdigital dermatitis does not progress any further and responds well to topical treatment with antibiotic spray or foot-bathing. The most commonly used chemicals for footbaths are formalin (2-3%) or zinc sulphate (10%). Sheep should be held on a dry surface after treatment as returning immediately to pasture means the chemical may get more or less immediately washed off the feet. No real immunity develops although lambs seem to be more susceptible than adults. There is no appropriate vaccine.

Footrot This is the most common type of lameness in sheep worldwide. It is caused by the bacterium Dichelobacter nodosus which invades and under-runs the horn starting axially from the interdigital space, and follows an initial interdigital dermatitis infection with F. necrophorum. D. nodosus can only survive on pasture for a limited time (about 2 weeks according to information from Australia) but is maintained in a flock through chronically infected or carrier sheep. The disease only spreads in damp conditions where the temperature is above about 50°F. This means that it will spread in UK conditions during much of the year, except during cold winter weather. Bearing in mind that many sheep are housed during the winter where the disease will spread anyway, there are few times of year when spread will not occur. In contrast, in countries such as Australia which have prolonged dry, hot periods in the main sheep-keeping areas when the disease does not spread, non-transmission times can be defined and used for intensive treatment schedules to be implemented.

41 There are a number of serogroups or strains of D.nodosus which differ in virulence according to the proteases produced and the characteristics of the bacterial fimbriae. This leads to a variety of clinical presentations from mild or ‘benign’ disease showing little horn involvement (and which looks very like interdigital dermatitis), to severe or ‘virulent’ disease where much of the horn becomes detached with a foul-smelling greyish necrotic material present under the horn. The lesion always starts from the axial side of the sole but may in time progress across the entire sole and up the wall in severe cases, leading to loosening of much of the horn capsule. Footrot has traditionally been treated by extensive paring of loosened horn but it is now recognised that this is not necessary and may be counterproductive. Self-cure may eventually occur but it is not ethical to leave cases untreated in the hope that this will take place. Additionally, chronically or long-term infected feet often become misshapen and act as an on-going source of infection for other sheep. The best method of treating is to administer an injection of antibiotic (long-acting oxytetracycline is most commonly used) with local treatment with antibiotic spray or foot-bathing in 10% zinc sulphate solution. If zinc sulphate is used sheep need to stand in the footbath for up to 20 minutes to ensure sufficient penetration of zinc into the horn. The stand-in time can be reduced by the addition of surfactant to the footbath mixture. Formalin (no stronger than 5%) is sometimes used but is not welfare-friendly and can damage feet if used too frequently or at too strong a concentration. Copper sulphate is sometimes used, but, as it is toxic to sheep, there are particular disposal problems. Other proprietary products containing a variety of chemicals are available. Loose horn can be carefully trimmed if necessary several days after treatment with antibiotics or footbaths by which time healing is usually well under way. A vaccine is available which is curative as well as preventive and is a good starting point in controlling the disease in badly affected flocks. However the vaccine has an oily adjuvant which can cause lumps or even discharging abscesses at the injection site in some animals. It is also dangerous if accidentally injected into the human operator. Routine foot trimming has no part to play in preventing footrot and can in fact make the problem worse. This comes about as the result of close contact of sheep allowing spread of infection within often contaminated pens and physical damage to feet caused by excessive paring. Regular foot-bathing correctly carried out in good conditions can help to keep the disease to a low level but good control also depends on identifying and removing chronically infected animals from the flock. It is possible to eradicate the disease from a flock, as has been done in parts of Australia, but requires hard work and commitment on the part of owners and shepherds.

Contagious ovine digital dermatitis (CODD) This apparently new disease was first reported in UK in 1997 and is now quite widely distributed in some flocks in UK but apparently not in other countries with the possible exception of Uruguay. It was at first called ‘new virulent footrot’ but was later named CODD, as organisms isolated from typical cases resembled spirochetes (treponemes) found in digital dermatitis cases in cattle. However these were only isolated from 70% of cases tested and D. nodosus was also isolated from some, so microbiologically the picture is confusing (Moore et al, 2005a and b). Certainly the disease presentation differs clinically from classic footrot, with lesions beginning as ulcerations at the coronary band with rapid undermining of the horn capsule from the coronary band downwards, often with haemorrhage present. The whole horn capsule becomes detached but the foul smell associated with footrot is absent. In chronic untreated cases permanent damage to the foot may result. In affected flocks many animals can be involved and it is a major welfare issue. Unfortunately virtually nothing is known about the epidemiology at present. Current treatment (unlicensed) is based on the use of sprays or footbaths containing lincomycin/spectinomycin or tylosin repeated 2 or 3 times. Tilmicosin by injection has also been used successfully, but antibiotics used commonly in sheep such as oxytetracycline or penicillin/streptomycin mixture have mostly had little effect. There is no vaccine.

Cattle There are many causes of foot lesions and lameness in cattle. The two common diseases caused by infectious organisms are interdigital necrobacillosis (foul-in-the-foot) and digital dermatitis. Solar ulcer, slurry heel and white line disease are also important but these are probably due to a combination of mechanical and environmental causes although lesions can become infected in the later stages. A more complete description of lesions and epidemiology can be found in Blowey (1993) and Murray et al (1996).

42 Interdigital necrobacillosis (Foul-in-the-foot) This has similarities to interdigital dermatitis in sheep being caused by F. necrophorum, but is a much more invasive and severe disease. Damage to the skin of the interdigital space allows invasion by bacteria which cause swelling and splitting of the skin and necrosis of the underlying dermis and deeper tissues. The whole foot is swollen and the affected animal is acutely lame. If untreated, the infection can spread into the pedal joint or up the flexor tendons. Treatment is usually by means of parenteral antibiotics.

Digital dermatitis This disease was first reported in Italy in 1972 and has since become widespread throughout cattle in many countries. Spirochetes (treponemes) have been implicated in the aetiology. Lesions start at the back of the foot between the bulbs of the heels. Initially these are circular erosions with exudation and formation of granulation tissue and are very painful. In advanced cases, a papilliform lesion develops, sometimes with hair (called ‘hairy warts’) and the lesion may progress to cause some under-running of the horn. Control is by cleaning the lesion and application of antibiotic, either by means of a spray or by foot-bathing (unlicensed use of antibiotics). Most outbreaks occur during housing and are associated with poor hygiene underfoot. Infection is introduced into previously uninfected herds by purchase of new stock.

REFERENCES 1. Blowey, R (1993) Cattle Lameness and Hoofcare. Farming Press, Ipswich. 2. Moore, LJ, Wassink, GJ, Green, LE and Grogono-Thomas, R (2005a). The detection and characterisation of Dichelobacter nodosus from cases of ovine footrot in England and Wales. Veterinary Microbiology; 108 : 57-67. 3. Moore, LJ Woodward, MJ and Grogono-Thomas, R (2005b). The occurrence of treponemes in contagious ovine digital dermatitis and the characterisation of associated Dichelobacter nodosus. Veterinary Microbiology; 111 : 199-209. 4. Murray, RD, Downham, DY, Clarkson, MJ, Faull, WB, Hughes, JW, Manson, FJ, Merrit, JB, Russell, WB, Sutherst, JE and Ward, WR (1996) Veterinary Record; 138 : 586-591. 5. Winter, AC (2004) Lameness in sheep: 1 Diagnosis. In Practice; 26 : 58-63. 6. Winter, AC (2004) Lameness in sheep: 2 Treatment and control. In Practice; 26 : 130-139. 7. Winter, AC (2005) Lameness in Sheep. The Crowood Press, Ramsbury, Marlborough.

43 NOTES

44 DISEASES OF THE FEET AND FACE IN SHEEP AND CATTLE. Agnes Winter BVSc, PhD, DSHP, DipECSRHM, FRAgS, MRCVS University of Liverpool, Leahurst Campus, Neston, CH64 7TE

Apart from the common diseases caused by infectious agents already described in the previous paper, there are many other lesions which affect the feet of both sheep and cattle and can cause lameness. In both species lesions of the white line are common. Interdigital hyperplasia is also seen in both cattle and sheep. Overgrowth of horn is common in both sheep and cattle. In sheep there is argument about the necessity to trim feet and it is generally agreed that many farmers trim unnecessarily and excessively. In cattle excessive horn growth is common and alters the balance of the foot and the stance of the animal and regular trimming to keep a good foot shape is recommended.

Sheep

White line disease This is a very common problem in cattle, pigs and horses as well as sheep but little attention has been paid to it in sheep (Winter and Arsenos, 2008). The white line is the specialised area of horn connecting the harder horn of the wall and sole (Kempson and Logue, 1993; Mulling, 2001), and is softer, allowing a degree of flexibility. White line lesions affect the quality and integrity of the horn at this important site in the foot. Many affected sheep are not lame but have the potential to become so if the horn defect becomes impacted with debris such as stones or leads to infection developing under the proximal part of the hoof wall. If this occurs the animal becomes acutely lame and pus eventually takes the line of least resistance and bursts out at the coronary band after which the animal gradually becomes sound again. White line lesions are generally thought to be multifactorial in origin – a possible combination of environmental effects, dietary effects on horn quality and effects of pregnancy have been suggested in cattle. In horses keratophyllic bacteria and fungi have been isolated from lesions and treatment with antiseptics have assisted recovery (Keller and others, 2000; Kempson and Robb, 2004; Apprich and others, 2006).In sheep it is difficult to identify the cause(s) as lesions are seen in all age groups from quite young lambs to old sheep, pregnant and non-pregnant females, males as well as females and in a variety of breeds.

Toe granuloma These are common in some flocks and often result from over-trimming, although they can be associated with chronic footrot or result from traumatic injury such as penetration of the sole by a sharp object. A strawberry-like outgrowth of granulation tissue develops at the site of injury, and, although loose horn may grow and partially cover it, the lesion rarely heals spontaneously.

Interdigital hyperplasia This is common in some breeds and may have a genetic basis. However as lesions generally do not develop significantly until animals are adult it can be difficult to avoid using affected animals for breeding. Small excess folds of skin develop in the interdigital space at the junction of the skin and coronary band, so there may be one or two present in between the claws of affected animals. As the animal grows these folds enlarge and become excoriated and infected, causing chronic lameness. They can be surgically removed, returning the animal to normal function, but may be perpetuated by breeding from such animals, particularly pedigree animals which otherwise may be good specimens of the breed.

Cattle As mentioned above, white line disease is a common problem in cattle and interdigital hyperplasia occurs in a similar way to that in sheep. Another important problem affecting cows feet, but not sheep, is described next.

Solar ulcer This is an extremely important condition which mainly affects the outer claws of the hind feet. A defect in the sole occurs at about the junction of the middle and posterior third of the sole in an area overlying the insertion of the deep digital flexor tendon into the pedal bone. Much discussion has been produced about the exact cause, but it does appear to be associated with

45 quality of horn and pressure on horn produced in the sole overlying the crucial structures in this area of the foot. Poor housing forcing cows to take excessive weight on the hind feet is also implicated. Once a problem has started in this area of the foot the cow adopts a characteristic stance to try to relieve pressure on the outer claw. This then leads to lack of wear of horn which exacerbates the problem. Corrective trimming and relief of pressure on the sole can help to manage the condition but ulcers are slow to heal and some animals never recover normality.

REFERENCES 1. Apprich, V, Spergser, J, Rosengarten, R and Stanek, C (2006) In vitro degradation of equine keratin by dermatophytes and other keratinophilic fungi. Veterinary Microbiology; 114 : 352–358. 2. Keller, M, Krehon, S, Stanek, C and Rosengarten, R (2000) Keratinopathogenic mould fungi and dermatophytes in healthy and diseased hooves of horses. Veterinary Record; 147 : 619-622 3. Kempson, SA. and Logue, DN (1993) Ultrastructural observations of hoof horn from dairy cows: the structure of the white line, Veterinary Record; 132 : 499-502. 4. Kempson, SA and Robb, R (2004) Use of a topical disinfectant as part of a hoof care programme for horses with diseases of the hoof capsule. Veterinary Record; 154 : 647-652. 5. Mulling, CKW (2002) Theories on the pathogenesis of white line disease-an anatomical perspective. Proceedings of the 12th International Symposium on Lameness in Ruminants, p.p 90-98. Orlando, Florida, USA. 6. Winter, AC and Arsenos, G (2008) White line disease in sheep; a common cause of misdiagnosis. In Practice (in press).

Diseases of the skin around the mouth and face in sheep and cattle Ulceration of the skin of the mouth area is a feature of important infectious viral diseases such as foot and mouth disease in cattle, sheep and pigs and bluetongue in cattle and sheep. Other diseases which can cause ulcers include BVD and Malignant Catarrhal Fever in cattle, Border disease in sheep and swine vesicular disease in pigs. It also became apparent during the FMD outbreak in 2001 that it is common for sheep to have traumatic ulcers in the anterior gum region and in some cases these were misdiagnosed as FMD. They were given the title of ‘Ovine Mouth and Gum Obscure Disease’ (OMAGOD lesions). Probably the most common and important skin disease of the mouth in sheep is contagious pustular dermatitis commonly known as orf. This does not affect cattle but is an important zoonotic infection in people working with sheep. Other diseases causing face lesions in sheep include staphylococcal dermatitis, photosensitisation, dermatophilosis and ringworm. Abscesses around the face of sheep are most commonly due to caseous lymphadenitis caused by Corynebacterium pseudotuberculosis, but can also be caused by Actinobacillus lignieresi . In cattle ringworm is the most common problem skin problem affecting the face.

Sheep

Orf (contagious pustular dermatitis, scabby mouth, sore mouth) This disease is common in all countries where sheep and goats are kept (Reid and Rodger, 2007). Although the classic lesions are seen around the mouth, it can affect other areas of the body such as the udder, coronet region, perineum or prepuce and can produce lesions on the poll and ears and other sites on the face and legs. In young lambs it develops in the mouth, affecting the gums around erupting teeth and sometimes extending into the oesophagus. The cause is a parapox virus, a large DNA virus with a characteristic basketwork shape. The virus can survive for many years in dried scabs but loses infectivity over weeks or months if exposed to moisture and weathering. Survival of virus in housing from one season to another can be a problem. The disease establishes in an area of skin or mucous membrane which has been damaged and targets newly regenerating epithelial cells. Erythema develops, followed by papules, pustules and scabs. The underlying dermis proliferates, often developing into papillomatous lesions or cauliflower-like growths. In most cases resolution takes place and scabs are shed within 4-6 weeks, but some animals appear to be unable to mount an adequate immune response and may develop a chronic or even overwhelming infection. Diagnosis is based on clinical signs, demonstration of characteristic viral particles by EM or by PCR.

46 Immunity is via a cell-mediated response, although humoral antibodies can be detected. Following an initial infection animals are not fully protected against further infections but recovery time is faster. Persistently infected animals showing no clinical disease may perpetuate infection in flocks or spread it into previously uninfected flocks (Nettleton and others, 1996) and it is not uncommon for flocks which have had apparently no disease for some years may suddenly have cases appearing. The unpredictability is a problem in dealing with the disease. A vaccine consisting of live virus which is applied to the skin by scarification is available and is commonly used. In effect, this gives animals the disease at a time convenient to the farmer rather than flaring up at crucial times such as just before autumn sales. The vaccine should never be used in flocks which have not experienced disease and needs to be used with care in other flocks. Scabs containing live virus form after vaccination and are shed into the environment and can act as future sources of infection. Therefore ewes should be vaccinated well before lambing and not housed in accommodation to be used for lambing until at least 6 weeks after vaccination.

Staphylococcal dermatitis (periorbital eczema, facial dermatitis) This usually affects animals in confined conditions, particularly when feeding from limited trough space. Trauma of vulnerable parts of the face and legs caused by knocks when competing for food leads to the development of deep ulcerations covered by scabs which bleed easily when disturbed. These are seen around the eyes and on the nose and are surrounded by an area of hair loss. The cause is thought to be strains of Staphylococcus aureus which produce a range of virulence factors including haemolysins and coagulase (Scott and others, 1980). Healing can be slow and permanent loss of hair from the affected area can result, so can be of particular concern in flocks of pedigree or show sheep.

Photosensitisation (yellows, alveld, plochteach) This is a common problem worldwide. It arises in 2 main ways – by ingestion of plants containing photodynamic agents such as St John’s Wort, or as a result of liver damage which leads to incomplete metabolism of chlorophyll. A photodynamic breakdown product of chlorophyll produced in the rumen, phytoporphyrin (formerly called phylloerythrin), fails to be conjugated and excreted normally by the liver and therefore enters the general circulation, sensitising the animal to sunlight. Animals with light coloured heads and ears are most commonly affected as there is no pigment in the skin to provide protection. The face and ears swell dramatically in the acute phase, with exudation of serum, followed by drying and cracking of skin and scab formation. In the hepatogenous form jaundice is often present. If animals recover it is common for the tips of the ears to be lost.

Dermatophilosis (Mycotic dermatitis) This is caused by Dermatophilus congolenis and most commonly affects the woolled areas but can cause scabbiness around the muzzle and ears. Wetting or damage to the skin allows invasion of the motile zoospores which then multiply by developing hyphal filaments. Inflammation of the skin results in exudation of serum and scab formation. Immunity eventually develops but further wetting of the skin can allow repeated attacks to occur, so the disease is particularly seen in the wetter western parts of the country.

Ringworm This usually develops as a result of contact with infected calves, or keeping sheep in accommodation previously used for calves. Trichophyton verrucosum is the usual cause (Sargison and others, 2002). The usual picture is areas of hair loss and scabbing around the face, poll and ears.

REFERENCES 1. Nettleton, PF, Gilray, JA, Yirrell, DL et al (1996) Natural transmission of orf virus from clinically normal ewes to orf-naive sheep. Veterinary Record; 139 : 364-6. 2. Reid, HW and Rodger, SM (2007) Orf. In: Aitken, ID (Ed) Diseases of Sheep, 4th Edn. Blackwell Publishing, Oxford, pp297-301. 3. Sargison, ND, Thomson, JR, Scott, PR et al (2002) Ringworm caused by Trichophyton verrucosum – an emerging problem in sheep flocks. Veterinary Record; 150 : 755-6. 4. Scott, FMM, Fraser, J and Martin, WB (1980) Staphylococcal dermatitis of sheep. Veterinary Record; 107 :572-4.

47 CANINE CLAW DISEASES AND RESEARCH

John Reilly

Abstract not submitted NOTES

48 ANATOMY AND COMMON DISEASES OF THE EQUINE HOOF John Reilly

Abstract not Submitted NOTES

49 0.4% DIMETICONE SPRAY, A NOVEL CONTROL MATERIAL TO KILL FLEAS BY PHYSICAL MEANS

Jones I, Kidman ER, Burgess I

Medical Entomology Centre, Insect Research & Development Limited, Royston, UK

Presenting author: Jones I

INTRODUCTION The cat flea, Ctenocephalides felis, is a common pest of domestic animals and can be a cause of irritation and health problems in humans. Most products to control these pests rely upon neurotoxic insecticides, and many lack persistence to affect juvenile stages of the flea life cycle. Recent legislation, through the Biocidal Products Directive, has lead to the removal of some consumer products from the market and emphasized the need for a non insecticidal solution to the problem.

MATERIALS AND METHODS High molecular weight dimeticone, 0.4% in a volatile silicone base, was used as an aerosol sprayed on carpet. Cat flea adults and all development stages from a laboratory culture colony were exposed in vitro and in semi field conditions.

RESULTS All mobile stages of the flea life cycle placed on a pre-treated surface tried vigorously to escape contact with the dimeticone. Insects became physically immobilized within minutes without recovery. Exposed eggs failed to hatch and adult fleas were unable to escape from treated cocoons.

CONCLUSION 0.4% dimeticone spray has been shown to have a physical control activity against all stages of the cat flea. Tests showed this new product to have a knock down capability comparable to that of permethrin spray, whilst persisting in test arena area for months after application. The product has the capability to eliminate a flea infestation with one application.

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