Large and Farm Animal

Sampler

Chapter 5: Bacterial Skin Diseases From Color Atlas of Farm Animal Dermatology, Second Edition. by Danny W. Scott.

Chapter 3: Husbandry and Health Planning to Prepare for Lambing or Kidding: Ensuring Pregnancy in Ewes and Does From Practical Lambing and Lamb Care – A Veterinary Guide, Fourth Edition. by Neil Sargison, James Patrick Crilly, and Andrew Hopker.

Chapter 4: Head and Neck Surgery From Bovine Surgery and Lameness, Third Edition. by A. David Weaver, Owen Atkinson, Guy St. Jean, and Adrian Steiner. and Brendan Carmel. 295

5.1

Bacterial Skin Diseases

Folliculitis and Furunculosis Corynebacterium pseudotuberculosis Infection Dermatophilosis Pododermatitis Miscellaneous Bacterial Diseases Abscess Bacterial Pseudomycetoma Opportunistic Mycobacterial Infection Actinobacillosis Nocardiosis Clostridial Cellulitis Necrobacillosis

Folliculitis and Furunculosis Figure 5.1-1 Bacterial folliculitis. Erythema, papules, and crusts in Features the ventral abdominal area.

Folliculitis (hair follicle inflammation) and furunculosis (hair follicle rupture) are common and cosmopolitan. Cultural evaluations have not been reported, but anecdotal literature suggests that Staphylococcus aureus and S. intermedius are causative. Predisposing factors include trauma (e.g., environmental, insect/arachnid) and moisture. There are no apparent breed, sex, or age predilections. Lesions can be seen anywhere, most commonly over the muzzle, back, ventrum, and distal hind legs (Figs. 5.1‐1 to 5.1‐5). Lesion location is often indicative of inciting cause(s). Lesions consist of erythematous papules, pustules, brown‐to‐yellow crusts, epidermal collarettes, and annular areas of alopecia and scaling. Pruritus is typically only seen when inciting causes include insects and arachnids. Furuncles are characterized by nodules, draining tracts, ulcers, and variable pain. Affected animals are usually otherwise healthy. Pending the inciting cause(s), single or multiple animals Figure 5.1-2 Bacterial folliculitis with intertrigo. Perivulvar may be affected. hyperpigmentation and ulceration.

Figure 5.1-5 Bacterial folliculitis. Swelling and crusts on lower eyelid.

Figure 5.1-3 Bacterial folliculitis. Multiple annular areas of alopecia and crusts over the rump.

Figure 5.1-6 Bacterial folliculitis. Direct smear (Diff‐Quik stain). Degenerate neutrophils and large numbers of extra‐ and intracellular cocci (arrow).

Diagnosis

1) Microscopy (direct smears): Suppurative inflammation with degenerate neutrophils, nuclear streaming, and Figure 5.1-4 Bacterial folliculitis. Annular area of alopecia crust phagocytosed cocci (Gram‐positive, about 1 µm and scale on rump. diameter, often in doubles or clusters) with folliculitis (Fig. 5.1‐6). Furunculosis is characterized by pyogran- Differential Diagnosis ulomatous inflammation. 2) Culture (aerobic). Dermatophilosis, dermatophytosis, demodicosis, sterile 3) Dermatohistopathology: Suppurative luminal follicu- eosinophilic folliculitis and furunculosis, and zinc‐ litis with degenerate neutrophils and intracellular responsive dermatitis. cocci; pyogranulomatous furunculosis. Bacterial Skin Diseases 297

Corynebacterium Pseudotuberculosis phic bacteria (coccoid, club, and rod forms) that may Infection be arranged in single cells, palisades of parallel cells, or annular clusters resembling “Chinese letters”; bacteria Features usually few in number. 2) Culture (aerobic). C. pseudotuberculosis infection is uncommon and 3) Dermatohistopathology: Nodular to diffuse pyogran- cosmopolitan. The organism contaminates various ulomatous dermatitis and panniculitis. Intracellular wounds, and moisture and flies are important contribut- Gram‐positive bacteria not commonly seen. ing factors. There are no apparent age, breed, or sex predispositions. Lesions are solitary or multiple subcutaneous nodules Dermatophilosis or abscesses. The head, submandibular, and cervical regions are most commonly affected (Fig. 5.1‐7). Features

Dermatophilosis (“streptothricosis,” “rain rot,” and “rain Differential Diagnosis scald”) is a rare, cosmopolitan skin disease. Dermatophilus Other bacterial (e.g., Trueperella pyogenes, Burkholderia congolensis proliferates under the influence of moisture pseudomallei) and fungal infections. (especially rain) and skin damage (especially ticks, insects, and prickly vegetation). The disease is more common and more severe in tropical and subtropical Diagnosis climates and outdoor animals. There are no apparent 1) Microscopy (direct smears): Pyogranulomatous age, breed, or sex predilections. inflammation. Intracellular Gram‐positive pleomor- Lesions can be anywhere, but frequently present as exudation, matted hairs, thick crusts, and hair loss on the pinnae, dorsum, and distal legs (Fig. 5.1‐8). Lesion location may be indicative of inciting cause(s). The condition is typically neither pruritic nor painful. Multiple animals may be affected. Dermatophilosis is a zoonosis. Human skin infections are rare and characterized by pruritic or painful lesions in contact areas (especially arms).

Figure 5.1-7 Abscess. Abscess below mandible. Figure 5.1-8 Dermatophilosis. Crusts on dorsum. 298 Section 5: Camelid

Differential Diagnosis

Bacterial folliculitis, dermatophytosis, demodicosis, and zinc‐responsive dermatitis.

Diagnosis

1) Microscopy (direct smears): Suppurative inflammation with degenerate neutrophils, nuclear streaming, and Gram‐positive cocci (about 1.5 µm diameter) in 2 to 8 parallel rows forming branching filaments (“railroad tracks”) (Fig. 5.1‐9). 2) Culture (aerobic, difficult). 3) Dermatohistopathology: Suppurative luminal folliculitis and epidermitis with palisading crusts containing Gram‐positive cocci in branching filaments. 4) Polymerase chain reaction (PCR) (culture, animal samples).

Pododermatitis

Features

Pododermatitis is a multifactorial disorder seen in alpacas and llamas. Recognized causes include trauma, bacterial folliculitis (see this chapter), yeast infection (see Chapter 5.2), chorioptic mange (see Chapter 5.3), sarcoptic mange (Chapter 5.3), contact dermatitis (see Chapter 5.7), insect‐bite hypersensitivity (see Chapter 5.5), Figure 5.1-10 Pododermatitis. Interdigital skin is thickened and and zinc‐responsive dermatitis (see Chapter 5.8). Deep hyperpigmented with crusts and ulcers (cytology positive for infections are associated with Staphylococcus spp., cocci and rods). Trueperella spp., and Fusobacterium spp. Lesions are usually seen on the interdigital skin of one or multiple feet. Superficial inflammation is characterized by erythema, scales, crusts, and variable hyperpigmentation, lichenification, exudation, and waxy accumulations. Deep inflammation is characterized by ulcers and draining tracts (Figs. 5.1‐10 and 5.1‐11). Pruritus, pain, and lameness are variable findings.

Differential Diagnosis

Chorioptic mange, yeast dermatitis, sarcoptic mange, contact dermatitis, insect‐bite hypersensitivity, and zinc‐ responsive dermatitis.

Diagnosis

Pending the historical and clinical findings, diagnostic tests could include: 1) Cytology 2) Culture Figure 5.1-9 Dermatophilosis. Direct smear (Diff‐Quik stain). 3) Skin scrapings Branching filaments composed of cocci (“railroad tracks”) (arrow). 4) Biopsies. Bacterial Skin Diseases 299

Figure 5.1-11 Pododermatitis. Large interdigital plaque with crusts and ulcers (culture positive for coagulase‐positive Staphylococcus sp., E. coli, and Actinomyces sp.).

Figure 5.1-12 Abscess. Fluctuant abscess at commissure of lips.

Miscellaneous Bacterial Diseases

Abscess (Fig. 5.1‐12) Common and cosmopolitan; anywhere; usually penetrating wounds; subcutaneous firm to fluctuant nodules; especially C. pseudotuberculosis, T. pyogenes, and Streptococcus equi subsp. zooepidemicus (“alpaca fever” in South America); tooth root abscesses usually appear as mandibular nodules or abscesses with Actinomyces spp. and other anaerobes. Bacterial One case report in an alpaca; single‐ or multiple‐crusted, ulcerated nodules; especially legs; S. aureus; culture pseudomycetoma and dermatohistopathology (“botryomycosis”) Opportunistic Very rare and regional (Australia) in alpacas; Mycobacterium ulcerans; wound contamination; usually solitary mycobacterial nonhealing ulcer; especially leg or face; culture, PCR, and dermatohistopathology infection Actinobacillosis One anecdotal case report in an alpaca with no details; Actinobacillus lignieresi; culture and dermatohistopathology Nocardiosis Very rare and mostly anecdotal in llamas; abscesses; wound contamination; Nocardia asteroides; culture, PCR, and dermatohistopathology Clostridial cellulitis Anecdotal in alpacas; Clostridium septicum; “malignant edema”; culture Necrobacillosis Sporadic and cosmopolitan; wound contamination by Fusobacterium necrophorum biotypes A and B; especially lips, interdigital spaces, and footpads; moist, necrotic, ulcerative, and foul smelling; variable lameness and systemic signs; culture 300 Section 5: Camelid

References

Clark, M.D., et al. (2013) Cytology of the interdigital skin O’Brien, C., et al. (2013) Mycobacterium from healthy alpacas (Vicugna pacos). Jpn J Vet Dermatol ulcerans infection in two alpacas. Aust Vet J 19, 63–67. 91, 296–300. Clark, M.D., et al. (2013) Resident flora of the interdigital Rosychuk, R.A.W. (1989) Llama dermatology. Vet Clin N skin from healthy alpacas (Vicugna pacos). Jpn J Vet Am Food Anim Pract 5, 203–215. Dermatol 19, 211–215. Rosychuk, R.A.W. (1994) Llama dermatology. Vet Clin N Foster, A., et al. (2007) Skin diseases of South American Am Food Animal Pract 10, 228–239. camelids. In Pract 29, 216–223. Scott, D.W., et al. (2010) Skin diseases in the Fowler, M.E. (2010) Medicine and Surgery of Camelids, 3rd alpaca (Vicugna pacos): a literature review and ed. Wiley‐Blackwell, Ames, IA. retrospective analysis of 68 cases Kumar, A., et al. (2013) Characterization of Fusobacterium (Cornell University 1997–2006). Vet Dermatol necrophorum isolated from llama and alpaca. J Vet Diagn 22, 2–16. Invest 25, 502–507. 301

5.2

Fungal Skin Diseases

Dermatophytosis Yeast Dermatitis Miscellaneous Fungal Diseases Candidiasis Coccidioidomycosis Zygomycosis Dermatophytosis

Features

Dermatophytosis (“ringworm”) is said to be an uncommon, cosmopolitan disease in alpacas and llamas. In fact, only one case has been reported in an alpaca. Anecdotal reports indicate that it is most commonly caused by Trichophyton verrucosum, and less commonly by T. men- tagrophytes, Microsporum gypseum, and M. nanum. In temperate climates, the disease is most common in fall and winter, especially in confined animals. There are no apparent breed or sex predilections, and young animals Figure 5.2-1 Dermatophytosis. Crusted nodule on nasal philtrum are more commonly affected. (biopsy positive, culture not done). Lesions most commonly occur on short‐haired areas: head, face, distal legs, and perineum. Lesions Differential Diagnosis vary from annular areas of alopecia and scaling to thick grayish crusts. Lesions are nonpruritic and non- Bacterial folliculitis, dermatophilosis, demodicosis, sterile painful. Rarely, lesions are solitary, crusted hyperkera- eosinophilic folliculitis, and zinc‐responsive dermatitis. totic areas (especially upper lip) (Fig. 5.2‐1). Immunologically compromised animals may have Diagnosis severe widespread lesions (Fig. 5.2‐2). Multiple animals may be affected. Dermatophytosis in otherwise 1) Microscopy (trichography): Plucked hairs and scrap- healthy camelids usually spontaneously resolves over ings of surface debris placed in mineral or potassium the course of 3 to 4 months. hydroxide and examined for the presence of hyphae As T. verrucosum is the most common purported and arthroconidia. Note: In some cases, fungi may not cause, dermatophytosis in camelids is a potential invade hair shafts. zoonosis. 2) Culture (hairs and surface debris).

Figure 5.2-3 Yeast dermatitis. Interdigital skin is thickened, scaly, and waxy. Figure 5.2-2 Dermatophytosis. Widespread crusts, scales, and ulcers in an alpaca with combined immunodeficiency (area has been clipped).

3) Dermatohistopathology: Suppurative luminal folliculitis and pyogranulomatous furunculosis with fungal hyphae in follicular and surface keratin (may not be in and on hair shafts).

Yeast Dermatitis

Features

Yeast dermatitis is a rare to uncommon, cosmopolitan disorder of alpacas and llamas. The causative fungus has not been isolated in culture, but cytological examina- tions revealed budding yeasts identical in appearance to Malassezia species. There are no apparent age, breed, or sex predilections. Predisposing factors may include environment (moisture, filth), poor nutrition, and other skin disorders (e.g., chorioptic mange, zinc‐responsive dermatitis). Lesions are most commonly seen on the interdigital spaces (Figs. 5.2‐3 and 5.2‐4) and in intertriginous areas (axilla, groin, perineum). Lesion distribution is indicative of underlying cause(s). Affected skin is variably erythematous, thickened, and covered with greasy to waxy deposits. Hair loss may be marked in severe cases (Figs. 5.2‐5 and 5.2‐6). Pruritus is not usually present.

Differential Diagnosis Figure 5.2-4 Yeast dermatitis. Waxy debris in interdigital space.

Other causes of pododermatitis (see Chapter 5.1). 2) Dermatohistopathology: Numerous budding yeasts Diagnosis in surface and follicular keratin. 3) Culture (may be difficult and require special media, as 1) Microscopy (direct smears): Numerous unipolar some yeast species may be lipid‐dependent). budding yeasts (3 to 8 µm diameter) (“peanut” or 4) Polymerase chain reaction (PCR) (cultures, animal “footprint” shaped) (Fig. 5.2‐7). samples). Fungal Skin Diseases 303

Figure 5.2-7 Yeast dermatitis. Direct smear (Diff‐Quik stain). Numerous budding yeasts (arrow).

Figure 5.2-5 Yeast dermatitis. Alopecia, waxy accumulations, and matted hair coat on face, pinnae, and neck.

Figure 5.2-6 Yeast dermatitis. Waxy accumulation and matted Figure 5.2-8 Sporotrichosis. Multiple crusted papules, nodules, hair coat. and plaques on distal limb. 304 Section 5: Camelid

Miscellaneous Fungal Diseases

Table 5.2-1 Miscellaneous Fungal Diseases

Candidiasis One case report in llama; extensive areas of coalescent crusts on axillae, groin, perineum, and muzzle; moist, red, foul‐smelling ulcers under crusts; culture (Candida albicans) and dermatohistopathology Coccidioidomycosis Uncommon (llamas) to anecdotal (alpacas) in endemic areas (southwestern United States); Coccidioides immitis; variable systemic signs and occasional firm dermal papules, nodules, and plaques (often crusted and ulcerated); especially shoulder, digit, and perineum; culture and dermatohistopathology Sporotrichosis One case seen in a llama; multiple firm papules, nodules, and plaques on a distal limb; (Fig. 5.2‐8) dermatohistopathology and culture Zygomycosis One case report in llama; wound contamination with Conidiobolus coronatus; multiple papules and nodules on nostrils, muzzle, and lips; culture and dermatohistopathology

References

Atlee, B.A., et al. (1993) Llama dermatology. In Advances Fowler, M.E., et al. (1992) Coccidioidomycosis in llamas in in Veterinary Dermatology. Vol. 2. Pergamon Press, the United States: 19 cases (1981–1989). J Am Vet Med Ames, IA, pp. 413–416. Assoc 201, 1609–1614. Clark, M.D., et al. (2013) Cytology of the interdigital skin Moll, H.D., et al. (1992) Entomophthoramycosis from healthy alpacas (Vicugna pacos). Jpn J Vet Dermatol conidiobolae in a llama. J Am Vet Med Assoc 200, 19, 63–67. 969–970. Clark, M.D., et al. (2013) Resident flora of the interdigital Scott, D.W., et al. (2010) Skin diseases in the alpaca skin from healthy alpacas (Vicugna pacos). Jpn J Vet (Vicugna pacos): a literature review and retrospective Dermatol 19, 211–215. analysis of 68 cases (Cornell University 1997–2006). Fowler, M.E. (2010) Medicine and Surgery of Camelids, Vet Dermatol 22, 2–16. 3rd ed. Wiley & Blackwell, Ames, IA. 305

5.3

Parasitic Skin Diseases

Chorioptic Mange Psoroptic Mange Sarcoptic Mange Pediculosis Miscellaneous Parasitic Diseases Biting Flies Demodectic Mange Myiasis Ticks Trombiculidiasis

Chorioptic Mange

Features

Chorioptic mange is the most common mite infestation of alpacas in most parts of the world. The infestation is much less common in llamas. It is caused by the mite Chorioptes bovis. There are no apparent breed, age, or sex predilections. Mite populations are usually larger, and clinical signs may be more commonly seen, in winter. Transmission occurs by direct and indirect contact. Lesions are initially most commonly seen on the ventral tail, perineum, ventral abdomen feet, and medial thighs (Figs. 5.3‐1 through 5.3‐6). Lesions then extend to the axillae, interdigital spaces, and up to the fetlocks. The pinnae, face, neck, and dorsum are uncommonly affected. In cria, lesions may be initially confined to the tips of the pinnae. Initial erythema and papules progress to crusts, scaling, and hair loss. Pruritus is absent to mild. Typically, multiple animals are affected. Humans are not affected.

Differential Diagnosis

Zinc‐responsive dermatitis, sarcoptic mange (if severely Figure 5.3-1 Chorioptic mange. Nonpruritic scaling, crusting, and pruritic), and psoroptic mange (if pruritic). hair loss on the tail head, perineum, and hind legs.

Color Atlas of Farm Animal Dermatology, Second Edition. Danny W. Scott. © 2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc. Figure 5.3-2 Chorioptic mange. Nonpruritic crusts and hair loss in Figure 5.3-4 Chorioptic mange. Nonpruritic scaling and crusting axillary region. on ventrum.

Figure 5.3-5 Chorioptic mange. Nonpruritic scaling and crusting Figure 5.3-3 Chorioptic mange. Nonpruritic crusting and hair loss of interdigital skin. on the tail head. Parasitic Skin Diseases 307

Figure 5.3-8 Chorioptic mange. Mite eggs in skin scraping.

Figure 5.3-6 Chorioptic mange. Nonpruritic crusting and hair loss on distal limb.

Figure 5.3-9 Psoroptic mange. Pruritic crusting, scaling, and hair loss on pinna.

Psoroptic Mange

Features Figure 5.3-7 Chorioptic mange. Adult Chorioptes mite in skin scraping. Psoroptic mange is uncommon to rare in most parts of the world. It is caused by the mite Psoroptes bovis. There are no apparent breed, age, or sex predilections. Transmission Diagnosis occurs by direct and indirect contact. Mite populations are usually larger, and clinical signs more commonly 1) Microscopy (skin scrapings and/or combings in min- seen, in winter. eral oil): Psoroptid mites, 0.3 to 0.5 mm in length Lesions are initially most commonly seen on the head, (Figs. 5.3‐7 and 5.3‐8). Note: Mites are often more face, and pinnae (Fig. 5.3‐9). In some cases, only the numerous and easily found on normal‐appearing in‐ ear canals are involved. More widespread involvement contact animals. can be seen on the shoulder, back, rump, sides, and 308 Section 5: Camelid

perineum. Initial erythema and papules progress to Sarcoptic Mange crusts, scaling, and hair loss. Pruritus is moderate to severe. Animals with otitis externa usually show ear Features twitching, head shaking, and purulent otorrhea if secondary bacterial infection occurs. Sarcoptic mange (scabies, or “saran”) is uncommon to Economic losses occur through decreased appetite, rare in most parts of the world. It is caused by Sarcoptes weight loss, decreased fiber production, hide damage, scabiei var. auchinae. There are no apparent breed, age, and decreased meat production. Multiple animals are or sex predilections. Transmission occurs by direct and typically affected. Humans are not affected. indirect contact. Lesions are initially most commonly seen on the ventral abdomen and chest, axillae, and groin. Extension to Differential Diagnosis the medial thighs, prepuce, perineum, legs, interdigital Sarcoptic mange, chorioptic mange, cutaneous adverse space, face, and pinnae occurs over time. Erythema drug reaction, insect bites, and insect‐bite allergy. and papules progress to yellow‐to‐gray crusts, scales, lichenification, skin thickening, and hair loss. Pruritus is intense. Secondary bacterial pyoderma is common. Diagnosis Multiple animals are typically affected. 1) Microscopy (skin scrapings in mineral oil): Psoroptid Economic loss can be severe: decreased feed con- mites, 0.4 to 0.8 mm in length (Fig. 5.3‐10). sumption, weight loss, decreased fiber production, hide damage, and decreased meat production. Severe disease may result in death or euthanasia. Sarcoptic mange is a potential zoonosis. Affected humans develop pruritic erythematous papules with crusts and excoriations on the arms, chest, abdomen, and legs.

Differential Diagnosis

Psoroptic mange, chorioptic mange, adverse cutaneous drug reaction, and insect‐bite allergy.

Diagnosis

1) Microscopy (skin scrapings in mineral oil): Sarcoptid mites, 0.25 to 0.6 mm in length. In chronic cases, mites may be difficult to find.

Pediculosis

Pediculosis (lice) is uncommon to common in most parts of the world. There are no apparent breed, age, or sex predilections. Louse populations are usually larger, and clinical signs usually more severe, in winter. Transmission occurs by direct and indirect transmission. Chewing lice (Bovicola [Damalinia] breviceps) are Figure 5.3-10 Psoroptic mange. Adult mite. most commonly seen on the tail head, the dorsal midline, Parasitic Skin Diseases 309 and the sides of the neck and thorax. Sucking lice (Microthoracius mazzi, M. camelli) are most commonly seen on the head, neck, shoulders, and flanks. Moderate to heavy infestations produce pruritus, matting, loss of fiber, and variable scaling and crusting. Excoriation and secondary bacterial pyoderma may occur. Sucking lice may also produce anemia. Multiple animals are typically affected. Humans are not affected. Economic losses occur through decreased food intake, weight loss, decreased fiber production, and decreased meat production.

Differential Diagnosis

Sarcoptic mange, psoroptic mange, and chorioptic mange.

Diagnosis

1) Physical examination: Adult lice (1 to 4 mm in length) and/or ova (“nits”) (1 to 2 mm in length) are found on the skin surface or attached to fibers, respectively. 2) Microscopy (lice and fibers placed in mineral oil). Figure 5.3-11 Fly bites. Crusts and scales on the concave surface of the pinna, presumed to be caused by black flies (Simulium sp.).

Miscellaneous Parasitic Diseases

Table 5.3-1 Miscellaneous Parasitic Diseases

Biting flies (Fig. 5.3‐11) Uncommon to common; cosmopolitan; mosquitoes, black flies (Simulium spp.), horse flies (Tabanus spp.), and deer flies (Chrysops spp.); spring, summer, and fall; especially lightly haired areas (bridge of nose, pinnae, periocular region, axillae, groin, and perineum); asymptomatic to painful/pruritic papules, plaques, and nodules Demodectic mange Very rare; cosmopolitan; Demodex spp. follicular mites; single or multiple asymptomatic papules and nodules; exudate and crusts with secondary bacterial infection; especially face, neck, and chest; incise a lesion, express caseous content, mix with mineral oil, and examine with microscope Myiasis (“maggots” and “flystrike”) Uncommon and cosmopolitan; especially Lucilia spp., Calliphora spp., and Phormia spp.; especially late spring, summer, and early fall; any wounded/damaged skin; foul‐smelling ulcers with scalloped margins and a “honey‐combed” appearance, teeming with larvae (“maggots”); usually painful and pruritic Ticks Little nonanecdotal information; Otobious megnini (spinose ear tick) commonly affects llamas and alpacas in the western United States; produces head shaking, scratching/rubbing ears, and otorrhea. Trombiculidiasis One report from Peru; Eutrombicula spp.; late summer and fall; infested woods and fields; no (“trombiculosis,” “chiggers”) apparent breed, age, or sex predilections; erythema, scale, crusts, pruritus, and traumatic hair loss on face; red‐to‐orange, 0.2 to 0.4 mm length larvae periorbitally 310 Section 5: Camelid

References

Ballweber, L.R. (2009) Ecto‐ and endoparasites of new Rosychuk, R.A.W. (1989) Llama dermatology. Vet Clin N world camelids. Vet Clin Food Anim Med 25, 295–310. Am Food Anim Pract 5, 203–215. Foster, A., et al. (2007) Skin diseases of South American Rosychuk, R.A.W. (1994) Llama dermatology. Vet Clin N camelids. In Pract 29, 216–223. Am Food Anim Pract 10, 228–239. Fowler, M.E. (2010) Medicine and Surgery of Camelids, Scott, D.W., et al. (2010) Skin diseases in the alpaca 3rd ed. Wiley‐Blackwell, Ames, IA. (Vicugna pacos): a literature review and retrospective Gomez‐Puerta, L.A., et al. (2012) Trombiculidiasis caused analysis of 68 cases (Cornell University 1997–2006). by chigger mites Eutrombicula (Acari: Trombiculidae) in Vet Dermatol 22, 2–16. Peruvian alpacas. Vet Parasitol 190, 294–296. Twomey, D.F., et al. (2010) Confirmation of the chewing Hill, F.I., et al. (2008) Demodex spp. infestation of alpacas louse, Bovicola breviceps, in a British llama (Lama (Vicugna pacos) in New Zealand. NZ Vet J 56, 148. glama) herd. Vet Rec 166, 790–791. Lusat, J., et al. (2009) Mange in alpacas, llamas and goats in Vine, N.J., et al. (2010) Sarcoptic mange in alpacas. Vet Rec the UK: incidence and risk. Vet Parasitol 163, 179–184. 167, 946–947. 61

Husbandry and Health Planning to Prepare for Lambing or Kidding: Ensuring Pregnancy in Ewes and Does

There is a perception amongst many small ruminant farmers and keepers that lambing or kidding represents the beginning of the annual flock or herd management calendar. Consequently, efforts aimed at ensuring a basis for optimal flock or herd production and welfare often begin with the management of parturient ewes or does and their lambs or kids, making lambing or kidding the busiest and most stressful time of year. However, a more efficient approach involves the concept of lambing or kidding being part of a continuum of sheep or goat husbandry, the outcome of which is determined by flock or herd management, and interventions occurring throughout the year. Thus, the foundations for a successful lambing or kidding period are laid long beforehand, during the approach to the mating period. This chapter describes reproductive management, nutrition and disease control, with regards to the requirements for reproduction and mating management.

Reproductive Management

The Breeding Season

Sheep and goats are more or less incapable of breeding for a large part of the year, and undergo repeated reproductive cycles during the breeding season until they become pregnant (described as being seasonally polyoestrous). The oestrous cycle starts and ends with the release of eggs capable of being fertilised (ovulation), and is about 17 days long in sheep. Ovulation is accompanied by behavioural changes known as ‘oestrus’ or ‘heat’. During oestrus, ewes are both attractive and receptive to rams. Ewes will seek out a ram and may adopt a crouching posture, while displaying tail wagging or nuzzling the ram’s flank before standing to be mated. Oestrus lasts for approximately 36 hours in sheep, and ovulation occurs 18–24 hours after it begins. The first oestrus of the season is often described as being silent, whereby ewes display no behavioural signs. Ewe lambs often have slightly shorter oestrous cycles than mature ewes, and frequently do not display overt oestrous behaviour; hence, the general advice that they should be mated by experienced rams of high libido.

Practical Lambing and Lamb Care – A Veterinary Guide, Fourth Edition. Neil Sargison, James Patrick Crilly and Andrew Hopker. © 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd. 62 Practical Lambing and Lamb Care

Onset of the breeding season in sheep is driven by short day length. Sheep are short‐day breeders so, for most breeds originating from northerly latitudes, the natural mating period is in autumn. Coupled with a pregnancy of about 145 days (about five months), this naturally results in lambs being born in the spring, coinciding with fresh herbage growth that provides sufficient nutrition to support the high energy demands of late pregnancy and lactation. Certain sheep breeds originating from equatorial latitudes have much longer breeding seasons. The physiological mechanism governing the onset of the breeding season is the release of a hormone called melatonin from the pineal gland region of the brain during the hours of darkness. As the day length decreases, melatonin release increases, indirectly stimulating release of the hormones which control the reproductive cycle, resulting in a return of fertility. The breeding season is defined as starting once all healthy ewes are cycling, following a transitional period when a few are cycling. In fact, the majority can be induced to cycle during the transitional period, using synthetic reproductive hormones. Rams are likewise affected by the change in day length, with testicular size, sperm production and libido peaking in the autumn. There are breed differences in the length of the breeding season, char- acterised by more northerly and mountain breeds having a shorter breeding season than lowland breeds, although variation between breeds can be significant.

Breed Selection with Reference to Reproduction and Lamb Care

The choice of appropriate dam and sire breeds is an important part of the preparation for lambing. Breed selection is also important with reference to other key performance indicators, such as carcase conformation, lamb growth, or milk yields. Breeds should be appropriate for particular management systems and environ- ments. For example, hardy, easy‐lambing breeds such as the Swaledale, Cheviot, Shetland or Scottish Blackface are more appropriate for outdoor lambing with minimal intervention (Figure 3.1) than more prolific ewe breeds producing large lambs.

Figure 3.1 Scottish Blackface ewes are well suited to the harsh conditions in which they are kept. Ensuring Pregnancy in Ewes and Does 63

Table 3.1 Breed selection criteria with reference to lambing management.

Characteristic Relevance

Length of the Earlier lambing is possible for breeds with longer breeding periods. breeding period Longer breeding periods allow the better use of reproductive manipulation within the transition period. Litter size Selection for large litter sizes can improve production and profitability, but increases the risk of lamb losses unless accompanied by appropriate nutrition and lambing management. Mothering ability Under lambing systems involving minimal intervention, the ewes’ mothering ability must be good in order to minimise the risk of lamb abandonment and subsequent lamb losses from hypothermia and/or starvation. Hardiness Sheep kept on extensive grazing, where they are exposed to adverse weather and potentially restricted nutrition, must be hardy to cope with, and avoid loss of, ewes and lambs. Pelvic Pelvic conformation varies between and within breeds. Ewes with conformation narrow or unnaturally angled pelvises have a high risk of requiring assistance at lambing, and hence require intensive supervision.

However, mountain breeds, with short breeding seasons, slow growth rates and relatively poor carcase conformation, would be a poor choice for early lambing indoors in January with the aim of producing lamb meat for the Easter mar- ket, compared with lowland breeds such as the Suffolk or Dorset. Characteristics which should be considered when selecting appropriate breeds with relevance to lambing management are shown in Table 3.1. Rams contribute 50% of the genetic make‐up of a flock’s lamb output. However, what may be desirable characteristics in the mother may not be so in the offspring if they are intended for different purposes. Hence, the pater- nal genetic contribution must also be considered to produce optimal offspring, without compromising the important characteristics of the ewe flock (Figure 3.2).

Selection of Animals for Culling

Selection of ewes for removal from the breeding flock should be a continuous process with the aims of: i) removing unhealthy animals which are not productive; ii) removal of ewes with defects or poor production traits that may be passed on to their lambs; and iii) removal of ewes whose management necessitates inputs that are out of pro- portion to their contribution to flock production.

These aims often overlap. For example, chronically lame sheep are likely to be in poor condition, so are not as fecund as, or produce less milk than, their sound counterparts. These poorly productive animals require repeated and often 64 Practical Lambing and Lamb Care

Figure 3.2 Terminal sire rams such as the Texel breed are suited to the production of fast‐growing lambs with good carcase conformation.

unsuccessful treatment to alleviate their suffering, and their lameness may have a heritable component, as in the case of poor limb conformation. Thus, the decision to cull chronically lame ewes is based on a range of voluntary and involuntary considerations. Various reasons for culling are first identified in pregnant and lambing ewes. However, it is usually inappropriate to cull these animals before weaning. Consequently, problems arising at lambing should be recorded, and ewes identified and marked for subsequent consideration. Examples of common periparturient problems that should be considered as reasons for culling are given in Table 3.2. Weaning is an opportunity to examine the entire ewe flock and select animals for culling (Figure 3.3). Additional factors to consider at weaning are shown in Table 3.3. Weaning also affords an opportunity to assess disease levels across the flock as a whole, while most of the ewes and lambs are present. Lameness levels, evidence of previous mastitis and average body condition scores all give valuable information on the general flock health status. Where a flock has a known problem with untreatable chronic diseases, such as maedi‐visna, Johne’s disease, ovine pulmonary adenocarcinoma (jaagsiekte) and caseous lypmphadenitis, specific culling policies to minimise the spread and impact of these diseases on productivity should be implemented. In the absence of a flock‐wide or a ram‐specific breeding soundness problem, 2% or fewer ewes bred within the breeding season should be barren after a mating period spanning two reproductive cycles. Such ewes may be incapable of breeding, or they may have inherently poor natural fertility. Hence, retaining Ensuring Pregnancy in Ewes and Does 65

Table 3.2 Common periparturient problems for consideration as reasons for culling ewes.

Problem Decision Reason

Vaginal prolapse Cull Affected animals are more likely to prolapse in subsequent years. Uterine prolapse Cull or Often occurs in young or old ewes in poor body retain condition, or associated with hypocalcaemia. Recurrence is unlikely once predisposing causes are managed. Difficult lambing Retain The problem is most likely to have arisen due to (dystocia) due to foetal management factors, and is unlikely to be directly malpresentation heritable. Dystocia due to failure Cull The problem may be heritable or may be a result of of cervical dilation previous scarring of the cervix. It is likely to recur (ringwomb) in subsequent years. Dystocia due to poor Cull The problem is related to the genetic makeup of pelvic conformation the ewe. Dystocia due to foetal Cull or If the problem is due to maternal factors, culling is oversize retain advised; however, if due to excessive nutrition or inappropriate choice of sire, it can be avoided in subsequent years. Ewe requiring Cull or The reason for the ewe requiring Caesarean section Caesarean section retain should be considered. Some fail to re‐breed. Poor mothering Cull or Ewes showing poor mothering ability in extensive behaviour retain management systems should be culled. Under more intensive systems, the problem may be a result of inexperience or inappropriate management. Mastitis Cull Udder damage will inevitably result in poor milk production in subsequent lactations. Poor milk production Cull or If poor milk production is an individual animal retain problem, the affected ewe should be culled. If it is a flock problem, the cause may be nutritional and remedied in subsequent years. Check for mastitis before retaining. Hypocalcaemia (milk Retain The problem is related to stress and nutritional fever) management. Hypomagnesaemia Retain The problem is related to stress and nutritional (staggers) management. Pregnancy toxaemia Retain The problem is related to large litter size and nutritional management. Pre‐pubic tendon Cull The rupture will not repair. rupture (ventral hernia) them and their offspring potentially lowers the average fertility of the flock, reducing productivity. These non‐productive ewes should be identified as early as possible, for example at ultrasound scanning for pregnancy, and then removed from the flock. 66 Practical Lambing and Lamb Care

Figure 3.3 Involuntary culling resulting from poor animal health must be kept to a minimum through planned management, allowing for flock genetic improvement through voluntary culling of less productive animals.

Table 3.3 Additional considerations for culling ewes at weaning.

Body Body condition score all sheep. Too low a score across the flock suggests a condition disease or management problem. Small numbers of thin ewes may be given access to better grazing or supplementary feeding. Very thin ewes and those which fail to improve should be culled. Teeth Ewes with missing or broken front teeth will find it harder to maintain condition on short grazing. Depending on severity, they may be managed separately or culled. Ewes with abnormal cheek teeth should be culled. Udder The udder should be palpated for evidence of mastitis, such as hard swellings, or discharging tracts. Ewes with evidence of mastitis should be culled. Feet Lame ewes struggle to maintain body condition. Ewes with uncomplicated or early infectious causes should be treated as appropriate. Ewes which remain lame despite treatment should be culled. Ewes with deformed feet, misshapen limbs or swelling of the joints should be culled, as they are unlikely to recover.

Selection of Replacement Breeding Ewes

Breeding replacements may be mated to lamb at either one year old (ewe lambs), or at two years old (referred to as yearlings, two‐tooths, or gimmers). In some flocks, breeding replacements may have been bred previously (for example, purchased as cast hill or upland ewes). All breeding replacements should be sub- jected to an examination similar to that performed on ewes at weaning. Where cast ewes are purchased as breeding replacements, the vulva should also be checked for evidence of scarring from retention sutures used for vaginal prolapses. Whenever possible, purchased replacements should be sourced from flocks of equal or higher health status, and should undergo a quarantine period and pro- tocol devised in conjunction with the farm’s veterinary health plan. Ensuring Pregnancy in Ewes and Does 67

As ewe lambs and gimmers have not lambed before, the likelihood of mastitis changes to the udder is low. A low tolerance should be shown towards poor body condition, because these animals have not experienced the high protein and energy demands of previous lactation. Replacements should have good general body conformation. Where replacements are homebred, they can be selected on the basis of performance as lambs (for example, having stood quickly, sucked quickly and grown rapidly), as well as on maternal performance (for example, preferentially retaining the offspring of ewes which lamb and successfully rear twins every year). Offspring of ewes identified as suffering from Johne’s disease, maedi‐visna or ovine pulmonary adenocarcinoma (jaagsiekte) should not be kept as replacements, as the close contact between ewe and lamb means that the lambs may be infected. The decision to breed replacement females for the first time as lambs or yearlings is not straightforward. Breeding as ewe lambs has the advantage that unproductive animals do not need to be kept for an entire year. However, the system requires careful planning and meticulous attention to detail in order to avoid disappointing fertility and fecundity, unsatisfactory levels of lambing intervention, poor lamb survival, retarded growth, loss of maternal body condition and poor fertility during the following year. Breeding as yearlings also requires good management, but is a more forgiving system. Ewe lambs must achieve at least 60% of their expected mature bodyweight at mating, and should be in good body condition (score 3.0–3.5 on a five‐point scale). Ewe lambs that are thinner or smaller than this will have reduced ovulation rates and poorer milk production. Unlike the situation when feeding pregnant yearlings and adult ewes – where provision must be made for maintenance, foetal growth and lactation – when feeding pregnant ewe lambs, the additional requirements for their own growth must also be considered.

Ram Breeding Soundness Examination

Rams should be examined about three months before the start of the mating period. This allows adequate time for correction of problems, or for culling and sourcing replacements. Rams should be in good body condition, but not fat at mating (score 3.5–4.0 on a five‐point scale). Good limb and mouth conformation is important in rams, both due to their contribution to the genetic make‐up of their lambs, and because animals with poor conformation may become lame or thin and, hence, may not remain sound and active throughout the mating period. Rams should be checked for tooth abnormalities, visual impairment, lameness and brisket sores, each of which can reduce their breeding soundness (Figure 3.4). The rams’ scrotal contents should be palpated (Figure 3.5). The testes should be freely mobile within the scrotum, evenly sized and have an even, slightly yield- ing feel. Testicular size is correlated with potential for sperm production. This can be judged by gently pressing the testes into the bottom of the scrotum, using a hand applied around the scrotal neck, and then measuring the circumference of the scrotum at its widest point. Most mature rams should have a scrotal circumference at its widest point between 30–40 cm. Outside the breeding season, 68 Practical Lambing and Lamb Care

Figure 3.4 Rams need to be physically sound as well as being reproductively sound.

Figure 3.5 Palpation of a ram’s scrotal contents can be conducted with the animal standing, or cast onto its hindquarters. Sargison 2008. Reproduced with permission of John Wiley and Sons.

the scrotal contents will shrink and be less firm, but at no point should they be widely different in size, or of variable texture. The tails and heads of the epididymes, where sperm matures and is stored after production in the testes, are easily palpated below and above the testes. These should be attached to the testis, albeit with a clear boundary. They should feel firm and smooth, but not swollen or painful, and there should be no discharging tracts (Figure 3.6). Ensuring Pregnancy in Ewes and Does 69

Spermatic cord and neck of scrotum - inguinal lymph node abscess - inguinal hernia - vasectomy scars

Head of epididymis - epididymitis/spermatic granulomas

Testis - cryptorchidism - hypoplasia Scrotum - orchitis - scrotal mange - discharging sinuses - infected shearing cuts

Tail of epididymis - epididymitis - segmental aplasia

Figure 3.6 Diagrammatic representation of what is palpated during ram breeding soundness examination. Sargison 2008. Reproduced with permission of John Wiley and Sons.

A purple‐coloured flush of the skin of the inner thigh occurs during the breeding season, reflecting elevated testosterone levels. The scrotal skin should be thin and supple. The scrotum and its contents should hang well below the body of the standing ram, providing a cooling effect that aids sperm production and matura- tion. Any thickening or inflammation of the scrotum can result in an elevated temperature in the scrotum, and may impair sperm production. The penis can be extruded by grasping it firmly at its base while the ram is restrained on his rump. The penis should not be attached to the prepuce (sheath), and there should be no obviously abnormal swellings, inflammation or discharge. Electroejaculation and ram examination must not be performed routinely, but may be helpful only in cases where an individual has been identified as having poor or suspect reproductive performance, yet clear abnormalities have not been found on physical examination. The procedure may only be performed by a veterinary surgeon. In some cases, ultrasound examination of the scrotal contents can be a useful adjunct in the diagnosis of abnormalities.

Selection of Replacement Rams

Replacement rams should have no detectable abnormalities on breeding soundness examination. They should have a large scrotal circumference relative to their age and time of year. They should also have good body conformation and general health. Consideration must be given to good biosecurity and disease control. 70 Practical Lambing and Lamb Care

Rams should not be introduced into tick‐infested areas from areas with no ticks. This is to avoid the risks of tick‐borne diseases which can affect breeding soundness, such as tick‐borne fever, occurring in the naïve introduced animals. Care must be taken to ensure that home‐bred replacement rams are not used on their own relatives. Home‐bred rams should be selected on the basis of recorded data for their vigour as neonates, growth rates, health and performance in the face of disease challenges. Where the dam’s breeding history is known, those rams whose mothers who have performed favourably, for example showing good mothering ability, should be preferentially selected.

Biosecurity

Effective biosecurity to prevent the introduction of new diseases or problems necessitates: ● isolation and quarantine; ● assessment of the risk of introduction of specific problems; ● appropriate treatments on arrival; ● sourcing animals from flocks with similar or higher status for freedom from specific diseases; and ● preventing diseases in the introduced animals that are already endemic in the main flock. The period of time for which animals are kept in quarantine should be sufficient to allow them to be clinically examined for the presence of disease (for example, footrot or contagious ovine digital dermatitis) and successfully treated as required. The threat of introduction of anthelmintic resistant nematodes is always present, so animals should be treated with a combination of anthelmintic drugs that is likely to be effective against resistant parasites on arrival. Effective treatments to remove sheep scab mites and anthelmintic resistant liver flukes should be given, depending on the risk assessment. Knowledge of the disease‐ freedom status of source flocks depends on the availability and understanding of the use of diagnostic tests – for example, used in the Premium Health Scheme for chlamydial abortion in the UK. Control of endemic diseases might involve vaccination and strategic treatments.

Breeding Replacement Selection Policies

There is a great deal of between breed and within flock variation as regards many traits. Some of this variation is acquired and some has a genetic basis, but the majority of traits are influenced by both factors. For example, the milk production of an individual ewe is dependent on the adequacy of nutrition during lactation, prior effects of the diet on udder development as a ewe lamb, and damage caused by mastitis and current demands, as well as her genetic potential. Selection for production traits is possible, but only improves economic productivity when the animals’ environment and management are appropriate. For example, it is pointless trying to breed ewes for genetically greater milk production if their diet fails to provide sufficient nutrients to allow them to produce Ensuring Pregnancy in Ewes and Does 71

Table 3.4 Steps in the genetic selection process for production traits.

Identification of the Selecting for several traits at once results in slower progress than trait(s) for selection selecting for one single trait. Some traits respond better to selection than do others. Scoring of animals for Good record‐keeping is important to identify animals with production traits desirable traits and take into account the performance of their relatives. Selection of animals The more heavily a trait is selected for, the more quickly a population average shift is seen. Removing the bottom 5% each year may rid the flock of problem animals, but will probably not shift the average. Removal of the bottom 50% will shift the average quickly, but will also reduce the flock size to unviable levels. Selecting rams is a good compromise, as individuals contribute more to the next generation than individual ewes. Similar to selecting rams is only keeping offspring from the top 50% of the ewes. Rams may be selected both for their own traits, and this can also be based on the performance of their offspring. more milk, or if mastitis is so widespread that the extra production potential is cancelled out by the large number of ewes with damaged udders. Equally, selecting for some traits may inadvertently select for other undesirable traits, or may select against a different desirable trait. However, provided these limitations are borne in mind, selection for certain production traits can help produce flocks that are tailored to particular environ- ments, management systems and producer aims. The selection process is out- lined in Table 3.4. Traits for which differences exist between breeds have proved to be amena- ble to selection – for example, for milk production, fecundity and wool quality. Within breed selection for sheep that are resistant (selecting for low worm egg counts) and/or resilient (selecting those which grow best in the face of high levels of challenge) to gastrointestinal roundworm infection has also been achieved.

Nutrition with Reference to Reproduction

There is no period of a ewe’s life when nutrition does not have an impact on her current and future productivity. As an example, all the eggs a female mammal will ever have are generated prior to birth, while still a foetus. Restricted energy nutrition as a foetus in the uterus of an undernourished dam will reduce the potential future productivity of the ewe lamb. Failure to provide good nutrition for ewe lambs not only reduces their fertility at first mating, but also has a life- long effect on fecundity. Poor ewe lamb nutrition also restricts udder development, limiting future milk‐producing capacity. Careful nutritional management is important between weaning (when the demands of lactation cease) and mating, for the ewes achieve optimal body condition for mating (score 2.5–3.5 on a five‐point scale). This helps to ensure the 72 Practical Lambing and Lamb Care

maintenance of good body condition throughout pregnancy, while achieving the highest ovulation rates and largest potential litter sizes. It generally takes about one month of improved nutrition to increase body condition score by 0.5 points. Ewes which are identified at weaning as being in poorer condition can be given access to better grazing than ewes which are already in better body condition. Thinner ewes can be weaned earlier, allowing them a longer period to gain body condition, while fatter ewes can be left with their lambs for a longer period. Supplementary feeding of thinner ewes can be instigated where better quality herbage is not available. Increasing the plane of nutrition for a few weeks before mating (referred to as flushing) can result in increased ovulation rates. The effect of flushing is greatest in ewes that are in sub‐optimal body condition, as they increase their food intake in response to the greater availability. Ewes that have already reached target body condition score will already be ovulating at their maximal rate and, hence, do not respond to flushing. Ewes which are in very poor condition are unlikely to respond to flushing. The effect of flushing in ewes that are in sub‐optimal body condition at mating may not be desirable, unless good nutrition can be maintained throughout pregnancy. Failure to maintain good levels of nutrition in these animals may lead to high rates of embryo loss, and increases the risk of having insufficient body stores to cope with the demands of a multiple‐foetus pregnancy and rearing multiple lambs. Hence, flushing is only likely to be beneficial if ewes are in sub‐optimal, but not poor, condition prior to mating, and nutritional management is such that they will have sufficient resources, in terms of body stores as well as food intake, to cope with the energy and protein demands of multiple‐foetus litters. Shorter periods of flushing can be effective where some degree of synchronisation is in place. Follicular development is controlled both by a hormone, leptin, which is affected by levels of body fat and long‐term energy intake, and by glucose and insulin, which are affected by energy intake over a period of 2–3 days. Glucose and insulin elevations during the late luteal phase are sufficient to increase the numbers of follicles ovulated.

Body Condition Scoring

An objective system of body condition scoring is necessary to overcome differences in individual’s perceptions of thinness and fatness, and to clearly define targets. Ewes are scored on a range of 1–5. Half scores are used to increase individual’s precision, but are highly subjective, and may vary greatly, depending upon sheep breeds, wool length and operators. The score is related to the degree of fatness in the lumbar region of the back, and is assessed in four stages:

i) The degree of prominence of the spinous processes of the lumbar vertebrae, as judged by the ease with which they can be felt and differentiated from each other. ii) The prominence and degree of fat cover over the ends of the transverse processes, as judged by the ease with which the bones can be palpated. Ensuring Pregnancy in Ewes and Does 73

Figure 3.7 Body condition scoring by palpation of the lumbar vertebrae.

Figure 3.8 A cross‐section through the lumbar spine. The numbers refer to 1 the stages (i to iv above) in the 4 assessment of body condition. From Russel (1984). Body condition scoring 2 of sheep. In Practice 6(3): 91–93. 3

iii) The degree of muscle and fat cover beneath the transverse processes, as judged by the ease with which the fingers may be passed under these bones. iv) The fullness of the eye muscle and fat in the angle between the spinous and transverse processes.

The process is undertaken in standing animals (Figure 3.7). These stages are shown in Figure 3.8 and described in Table 3.5.

Trace Element Deficiencies

The roles of trace element deficiencies on reducing reproductive performance are generally overstated. Copper and cobalt deficiencies cause ill thrift so may compromise the achievement of target body condition scores, with knock‐on effects on reproductive performance. Iodine and selenium deficiencies have direct effects on early embryonic survival. Monitoring of the trace element status of ewes or does, and appropriate supplementation before mating, is therefore recommended. Regions in which the soil and pasture is selenium‐deficient are 74 Practical Lambing and Lamb Care

Table 3.5 Body condition scoring for ewes. Half scores can be allocated, but are very subjective. A score of 0 is sometimes used to describe a state of total emaciation at the point of death.

Score Description

1 Spinous processes are prominent and sharp. Transverse processes are also sharp, the fingers pass easily under the ends and it is possible to feel between each process. Loin muscles are shallow, with no fat cover. 2 Spinous processes are prominent, but smooth. Individual processes can be felt only as fine corrugations. Transverse processes are smooth and rounded and it is possible to pass fingers under the ends with a little pressure. Loin muscles are of moderate depth, but have little fat cover. 3 Spinous processes have only a small elevation, are smooth and rounded. Individual bones can be felt only with pressure. Transverse processes are smooth and well‐ covered, and firm pressure is required to feel over the ends. Loin muscles are full and have a moderate degree of fat cover. 4 Spinous processes can just be detected with pressure. Ends of transverse processes cannot be felt. Loin muscles are full and have a thick covering of fat. 5 Spinous processes cannot be detected, even with firm pressure. There is a depression between the layers of fat in the position where the spinous processes would normally be felt. Transverse processes cannot be detected. Loin muscles are very full, with very thick fat cover.

generally known. Iodine‐deficient soils do occur, but deficiencies are generally associated with inhibition of iodine uptake or metabolism by the thyroid gland. Feeding ewes solely on Brassica crops (which may contain high levels of goitro- genic substances that inhibit iodine uptake by the thyroid gland or its metabolism during mating and early pregnancy) is not recommended without provision of supplementary hay or an alternative grazing area.

Ram Nutrition

Rams must be in good body condition six weeks before introduction to the ewes, to ensure adequate sperm production and prepare them for the substantial weight loss that occurs over the mating period. A body condition of 3.5–4.0 (on a five‐point scale) for the beginning of mating is desirable (Figure 3.9). Excessively fat rams, as a result of high levels of concentrate feeding, have impaired sperm production and poor libido. Rams should, therefore, be allowed to gradually recover body condition after mating, and then to maintain their target body condition score for the rest of the year. High levels of concentrate feeding of sale ram lambs should be discouraged. Less is known about the effects of trace element deficiencies on sperm production in sheep and goats than in other species, but selenium deficiency is known to reduce sperm viability. If a trace element deficiency has been identified on farm, the rams should be supplemented in the same manner as the ewes. Excessive supplementation must be avoided. Ensuring Pregnancy in Ewes and Does 75

Figure 3.9 Rams and bucks must be fit and in good body condition score before the mating season, but not excessively fat. The buck in the image is suffering from ectoparasites and, hence, is likely to be sub‐fertile.

Toxins

Plants such as subterranean red clover, and certain fungi which can be found on pasture, conserved forage or concentrate feed, produce compounds which mimic the female hormone oestrogen. This occasionally causes high levels of infertility in groups of ewes. Affected ewes may have swollen vulvas and a degree of udder development which is unusual for the production stage. These phytotoxins and mycotoxins, respectively, may also impair the fertility of rams. Other plant toxins, as well as heavy metals, will interfere with reproduction, both by generalised effects on the ewes and rams, and also because embryos are particularly sensitive to toxic insult. Suspect cases should be investigated, and implicated pastures should not be grazed by ewes during the approach to mating or pregnancy.

Disease Control with Reference to the Mating Period

Various routine animal health measures are undertaken as part of a flock or herd health plan during the period between weaning and mating. Some of these treatments are required by all sheep on the farm, and some are specific for breeding ewes, rams or replacements.

Abortion Vaccination

No vaccine offers complete protection to 100% of vaccinated animals. The aim of vaccination is to produce a population where the vast majority of animals are immune, so that disease spread becomes impossible. Vaccination should be 76 Practical Lambing and Lamb Care

planned in advance, with careful consideration of which animals require vaccinating so as to maintain this level of immunity. Vaccination schedules differ between vaccines. Many require a primary course consisting of two injections to produce a protective level of immunity. Many also require a booster vaccination, usually annually, to keep the levels of antibodies and immune cells at protective levels. Vaccines, especially live vaccines, are delicate products, and should be handled with care and according to the instructions on the accompanying data sheet. A commonly encountered problem is failure to keep vaccines refrigerated until the point of use. Allowing purchased vaccines to warm up, or become exposed to direct sunlight, may result in expensive failures that could be prevented by a little forethought. Two highly effective live vaccines are currently available for the control of abortion caused by Chlamydia abortus. The vaccines are administered as a single intramuscular or subcutaneous injection at least four weeks prior to mating. Ewe lambs may be vaccinated from five months old. Protection lasts for at least three years, but it is common practice to vaccinate breeding ewes only once in a lifetime. These vaccines should not be used in pregnant animals, as to do so may not prevent abortions. Animals should not be under treatment with tetracycline antibiotics, as these will kill the live vaccine strain of C. abortus and render vaccination ineffective. C. abortus can cause disease in people, so appropriate care should be taken when administering the live vaccine, and pregnant women or immune compromised individuals should not handle it. A highly effective live vaccine is available for the control of toxoplasma abortion. The vaccine is administered as a single intramuscular injection at least three weeks prior to mating. Ewe lambs may be vaccinated from five months old. The data sheet claim is for protection lasting at least two years, but vaccinating breeding ewes only once in a lifetime is generally effective, due to boosting by natural challenge. The live Toxoplasma gondii tachyzoite vaccine can be given on the same occasion as the chlamydial abortion vaccines. It should not be administered to pregnant ewes, as to do so may cause abortions. Toxoplasmosis is an important disease in humans, so care should be taken when administering the live vaccine, and pregnant women and immune‐compromised individuals should not handle it. An effective vaccine was promptly developed following the emergence of the Schmallenberg virus as a cause of abortions and foetal malformations in sheep. The advisability of vaccinating against Schmallenberg virus depends on local conditions and the timing of mating and pregnancy. The vaccine is administered by a single subcutaneous injection to animals from the age of 2.5 months. It should not be used in pregnant animals, and no information is available on the duration of immunity conferred. Inactivated vaccines were developed against bluetongue virus serotype 8, following its incursion into northern Europe in 2008. The recommended adminis- tration programmes for the vaccines differ for the different products. Protective immunity lasts for six months to one year, but no booster regime has been agreed. Inactivated vaccines against serotypes other than BTV 8 are available in some countries. Ensuring Pregnancy in Ewes and Does 77

Live vaccines for the control of abortion due to Brucella melitensis are available in some countries. These are administered either by subcutaneous injection or by application to the conjunctival lining of the eyelid. Vaccination is frequently forbidden in some countries where this disease is not endemic, including the UK. Killed vaccines are available in Australia, New Zealand and North America for the control of abortion caused by Campylobacter foetus foetus. These give good protection after an initial two‐dose course prior to mating. Annual boosters are required. The vaccines are unlikely to be effective for the control of abortions caused by different strains of C. foetus foetus in other countries. Rift Valley fever is an important cause of abortion in small ruminants in Africa and the southern Arabian peninsula. Live, killed and mutagen‐attenuated vaccines are available. Live vaccines give prolonged protection, but should not be used in pregnant animals. Killed and mutagen‐attenuated vaccines are safe for use in pregnant animals. Inactivated Salmonella abortus ovis vaccines are available in some countries. Salmonella typhimurium vaccines available in certain countries have been shown to offer cross‐protection against S. abortus ovis abortion, as well as that directly due to S. typhimurium, but are ineffective in the control of abortion commonly caused by Salmonella Montevideo or Salmonella Brandenburg in the UK and New Zealand, respectively.

Lameness Control

The opportunity should be taken at weaning to assess flock lameness levels. Individual lame animals should be separated and treated. If lameness levels exceed reasonable targets of 2–5%, then the cause should be confirmed by veterinary investigation, and a control strategy developed and implemented. Lame sheep should be treated whenever they are seen, but this vigilance should be particularly intense in the run up to mating. Lame ewes will be in poorer condition at mating, and so will have reduced fertility and fecundity. Unresolved lameness throughout pregnancy will result in thin ewes being at greater risk of pregnancy toxaemia and also being likely to rear fewer and smaller lambs (Figure 3.10). Prompt treatment within three days of detection of footrot in ewes has been shown to result in a more rapid return to soundness than delayed treatment. Foot paring is unlikely to be necessary for the majority of sheep. Hooves generally become seriously overgrown because the animals are lame and not using the foot, and not vice versa. Footrot is best treated by topical application of oxytetracycline spray to the affected foot and an intramuscular injection of long‐acting oxytetracycline. Paring the foot is more likely to hinder healing than to cure the problem.

Sheep Scab Control

Sheep scab, caused by the surface dwelling mange mite, Psoroptes ovis, is a serious threat to the health of the flock. Affected sheep are extremely pruritic (itchy), and lose body condition due to the loss of protein‐rich fluid through the inflamed skin. 78 Practical Lambing and Lamb Care

Figure 3.10 Lameness can have a profound effect on ewe reproductive performance and on the growth of their lambs.

Figure 3.11 Sheep scab in pregnant ewes results in the birth of small weak lambs which impacts on lamb survival.

The impact of sheep scab on litter size, lamb birth weight and lamb growth rates can be very high (Figure 3.11). Sheep scab also has various legal implications. The disease is most frequently seen in the autumn and winter, coinciding with the mating period and early pregnancy. The movement of replacement breeding animals onto holdings can introduce disease, as can the return of sheep which have been away on summer or winter grazings. Ensuring Pregnancy in Ewes and Does 79

Sheep scab control measures will depend on individual flock circumstances. These may involve:

i) maintenance of a closed flock with secure boundaries, with prompt investigation of any itchy sheep; ii) non‐closed flocks with secure boundaries and quarantine treatment of bought‐in animals, or those returning from external grazings; or iii) whole‐flock treatments of non‐closed flocks with unsecured boundaries, coordinated between neighbours, timed to coincide with the quarantine treatment of any bought‐in animals. Treatments involve either plunge dipping in organophosphate suspensions or use of injectable macrocyclic lac- tone drugs.

Other External Parasite Control

Chewing lice are rarely a problem in adult ewes, and may be considered a minor nuisance in most flocks. In flocks where they are a problem, the best control measure may be the use of pour‐on synthetic pyrethroids after shearing. Organophosphate plunge dips for the control of sheep scab are also effective against chewing lice. Use of synthetic pyrethroid pour‐ons in long‐fleeced animals will reduce numbers and help prevent itching, but it is unlikely to eliminate the louse population entirely. Underexposure of lice to lethal drug concentra- tions is associated with the use of pyrethroid pour‐ons in long‐fleeced animals selects for drug resistance. Where chewing lice have been eliminated, an effective louse treatment should be included in the quarantine procedure, to avoid their reintroduction. Ticks often have peaks of activity in spring and in autumn. Where tick numbers are large and tick worry is a problem, then all sheep will benefit from either organophosphate plunge dipping or the use of a synthetic pyrethroid pour‐on prior to high‐risk periods. When naïve breeding replacements are to be introduced onto tick pastures before or during mating, then these animals may benefit from a treatment to prevent infection with tick‐borne fever and louping ill, which can cause reduced sperm production in males and abortion in females. A louping ill vaccine is available. Flystrike and fly worry tend to be less of a problem in shorn ewes than in lambs in the summer, but the risk period may extend into the autumn if temperatures permit. The need to protect ewes against flystrike and fly worry will be determined by local conditions.

Liver Fluke Control

Disease due to migrating larvae of the liver fluke, Fasciola hepatica, is common in the autumn (Figure 3.12). The liver damage caused by this can be severe enough to result in sudden death. Sub‐acute fasciolosis can cause marked blood loss and loss of condition as well as predisposing to sudden death due to the clostridial bacterial infection, black disease. 80 Practical Lambing and Lamb Care

Figure 3.12 Liver fluke infection during the mating period can have profound effects on ewe reproductive performance, and can influence the survival and growth of their lambs. Note the swelling under the chin, indicative of severe hypoproteinaemia.

The liver fluke is dependent on a mud snail, Galba truncatula, for part of its life cycle, so higher‐risk pastures can often be identified as those containing boggy areas. In wetter years, the level of fluke contamination on the pasture and the area contaminated can both rise significantly. Mitigation of losses due to sub‐acute fasciolosis can be achieved by a combination of factors. Wherever possible, grazing animals on high‐risk wet pastures should be avoided during the autumn and early winter. It may be helpful to fence off specific high‐risk areas. Measures aimed at reducing the mud snail habitat, such as providing hard standing areas around water troughs, planting trees and improving drainage, can be helpful. Most sheep flocks depend upon the use of flukicidal drugs. The most versatile flukicidal drug is triclabendazole, which kills all stages of fluke larvae down to a few days after infection. On heavily contaminated pasture, sheep may need several triclabendazole treatments throughout the highest‐risk period. Unfortunately, F. hepatica has evolved to become resistant to triclabendazole, and resistant strains are now reported in many countries. When triclabendazole resistance is present, it is necessary to use alternative flukicidal drugs, such as closantel, or nitroxynil, although these are not effective against immature stages. Hence, determining whether or not triclabendazole resistance is present is worthwhile. Ensuring that adult fluke inside sheep, cattle or goats are killed not only has health benefits for the treated animals, but also reduces the infection challenge to the snail intermediate hosts, hence reducing the level of fluke infection of livestock during the following autumn. Animals wintered inside should be tested for fluke infection and treated, if required, before turnout. Those outwintered should be treated in the spring, depending on the disease risk assessment. All flukicides kill adult flukes, so are appropriate for this purpose. Avoiding using Ensuring Pregnancy in Ewes and Does 81 triclabendazole at these times reduces the selection pressure for the development of triclabednazole resistance. Consideration should be given to avoiding the introduction of F. hepatica, and of resistant flukes to farms that do not already have a problem but have suitable snail habitats. In these cases, all bought‐in animals should receive a quarantine treatment. Two treatments of closantel or nitroxynil, at a 6–7 week interval, are advised. Whenever possible, animals should be kept in low‐risk areas such as sandy pastures, salt marshes or sheds during this period, or placed on fields being ploughed later in the year, so that any surviving resistant fluke eggs shed cannot complete their development.

Roundworm Control

Adult ewes usually have good immunity to gastrointestinal roundworms such as Teladorsagia circumcincta and Trichostrongylus spp., and do not need treating before or during the mating period. Anthelmintic treatment of ewes in the autumn may select for worms resistant to the drugs, and is unlikely to produce a significant production benefit. The situation differs with regards to the abomasal blood‐feeding roundworm, Haemonchus contortus. The risk of haemonchosis in ewes can be high, in particular in warmer regions following rainfall after a dry summer. Individual ewes may be affected to different levels, so selective treatments based on conjunctival colour (using the FAMACHA scoring system) may be effective and may help to reduce the risk of selection for anthelmintic resistance (Figure 3.13).

Figure 3.13 FAMACHA scores can be a useful index for the targeted selective treatment of haemonchosis in ewes. 82 Practical Lambing and Lamb Care

Specific Disease Control in Ewe Lambs

If ewe lambs are to be bred in their first year, they will require the same vaccina- tions as adults would receive on entry to the breeding flock. They will also need to have completed a primary course of any clostridial vaccination, to protect both themselves and their newborn lambs. Other routine health treatments given to the ewes should also be given to the ewe lambs. Unlike adult sheep, ewe lambs will not have developed good immunity to gas- tro‐intestinal roundworms, and so can suffer from parasitic gastroenteritis. An integrated control strategy of selective anthelmintic treatments and grazing management can help to ensure lack of disease and good growth rates, while exposing lambs to sufficient levels of roundworm challenge to allow the development of immunity.

Specific Disease Control in Rams

Rams do not require vaccination against agents which cause abortion only but, in some regions, it is wise to vaccinate them against diseases such as bluetongue and Rift Valley fever which cause fever, as this can affect sperm production, or against B. melitensis, which can infect the male genital tract and cause infertility. Rams should receive any of the treatments given to the rest of the flock to control lameness or parasites. Unlike females, males do not develop good protective immunity against gastrointestinal roundworms, so anthelmintic treatments before mating may be helpful.

Specific Disease Control in Introduced Animals

The aim of treatments of replacement breeding sheep or goats is to bring them to the same vaccination and disease status as the rest of the flock. Where the vaccination history is unknown or suspect, introduced animals should receive the primary courses of any vaccines which are currently in use in the breeding flock. Introduced sheep should be treated for sheep scab and for chewing lice, where the home flock is louse‐free. All introduced animals should be given a quarantine treatment with a combination of different anthelmintic drug groups, such as monepantel or derquantel, and ivermectin or levamisole. They should then be turned onto contaminated grazing which has recently been grazed by the home flock, to pick up the roundworms present in the home flock and to ensure that any potentially resistant parasites which survived the quarantine treatment are a very small percentage of the total population of that species. Based on disease risk assessment, replacement animals should be treated for liver fluke, as described above. Based on the disease risk assessment, introduced animals should be treated to remove any ticks. Potentially naïve animals introduced in the autumn to flocks in tick‐affected areas should be treated with an acaracide product with persistent activity. If louping ill is known to be present, replacements should be vaccinated. All bought‐in sheep should be foot bathed twice with either 2–3% formalin or 10% zinc sulphate, to avoid the import of contagious ovine digital dermatitis or novel strains of footrot. Ensuring Pregnancy in Ewes and Does 83

Mating Management

Good management during the mating period can maximise pregnancy rates, and can also aid flock management during lambing.

Length of the Mating Period

The oestrous cycle of ewes is 17 days long, and healthy adult ewes of most sheep breeds achieve 90% conception rates after natural service by a fertile ram during the breeding season. If the ewes are turned out with fertile rams for 17 days, then all should come into oestrus once during that time and be mated, with 90% becoming pregnant. If a further 17 days is allowed, then 90% of the remaining 10% should become pregnant, leaving 1% barren. A 34‐day (two oestrous cycles) mating period is considered standard for most flocks. A longer mating period can cover for deficiencies in the fertility of ewes and/or rams, but will result in a prolonged lambing period and associated problems.

Ram Numbers

Rams are expensive in terms of their value, the fact that they must be maintained all year for about one month of work, and in that the impact of an individual failure is high. Even a fit ram, with good libido and a healthy reproductive tract, can only serve a finite number of ewes in a certain time period. Various factors must be considered when calculating the most appropriate ram‐to‐ewe ratio. The more synchronised the ewe flock are as to timing of oestrus, the more ewes that will need to be served on any given day. Synchrony may arise as a management decision, or as a result of the ram effect and improved nutrition on mating paddocks. Very compact lambing requires synchrony of the ewes, and so a higher ram‐to‐ewe ratio. Conversely, the ram‐to‐ewe ratio can be reduced below normal levels if a longer mating period is allowed. Extensively managed flocks often naturally disperse into smaller sub‐groups, which may be widely distributed. This limits the ability of ewes to find the ram and vice versa. A highly dispersed flock on very broken ground will need a higher ram‐to‐ewe ratio, to ensure there is always a ram within the vicinity of any oestrous ewe. Rams with larger libido and greater sperm production will succeed in serving more ewes. Ram lambs will not be able to serve as many ewes as fully mature males. Examples of ram‐to‐ewe ratios appropriate to different management conditions are given in Table 3.6. The mating group size is determined by the ram‐to‐ewe ratio and the number of rams to be included in a single paddock. Using a single ram with a group of ewes (single‐sire mating) gives a guaranteed paternity record for any ewes mated during that period, but is a risky strategy, should the ram be unsound. Two rams may fight or, if one is far more dominant than the other, he may monopolise the ewes. However, if a ram is subfertile, the pregnancy rate will suffer. Three or more is generally considered the least risky policy. 84 Practical Lambing and Lamb Care

Table 3.6 Ram : ewe ratios for different conditions.

Appropriate Conditions ram‐to‐ewe ratio

Typical conditions of paddock mating lowland ewes, with a 34‐day 1 : 50 mating period and target pregnancy rate of 99% Using ram lambs, or with ewes synchronised by the ram effect 1 : 20 Hormonally synchronised ewes 1 : 10 Use of superior breeding capacity rams (completely sound, high libido, 1 : 60 scrotal circumference > 40 cm) with lowland ewes If a lower pregnancy rate or a prolonged mating period is acceptable 1 : 100

Figure 3.14 Keel marks can be used to show that rams are working, and to provide information about oestrus behaviour in ewes.

Raddle marking involves the application of paint to a ram’s brisket, or the application of a harness with a crayon attached, which lies over the brisket. These mark the ewe when the ram mounts. The colour of the paint or crayon may change with ram to record paternity, or with date to allow estimation of the lambing time. Keel marks can be used to detect failure of conception by ewes returning to oestrus and being marked a second time (Figure 3.14). Non‐cycling ewes are not marked. Keel paint must be reapplied frequently, and this is most easily done if rams are trained to come to a bucket for feed. Harnesses must be well fitted or they can cause rubbing, brisket sores or injury. They should be checked regularly, and should not be used on rams with brisket sores. Ensuring Pregnancy in Ewes and Does 85

Conception and Implantation

After fertilisation, the maintenance of pregnancy requires the conceptus (the result of the fusion between sperm and egg) to signal to establish pregnancy, prevent the further continuation of the oestrous cycle, and then to implant into the uterine wall. Implantation usually occurs around 14–16 days after fertilisation. During this period, the pregnancy is susceptible to stress – for example, changes in diet, or excessive moving or handling. It is recommended that minimal changes in management occur over the mating period, and for 16 days after the last ewe is mated.

Manipulation of Reproduction

It is possible to manipulate the ewes’ reproductive behaviour to advance the breeding season into the transition or anoestrous periods. This can allow lambing to occur at different times of the year, in order to take advantage of economic conditions, such as higher lamb prices or reduced feed costs. It is also possible to synchronise ewes to come into oestrus within a narrow timeframe, allowing a short lambing period. Before embarking on any reproductive manipulation programme, requisite preparation must be considered. If the breeding season is to be advanced so that a UK flock will be lambing in December, there must be sufficient shed space to house the ewes for lambing, and to keep the ewes and lambs housed until such time as the weather has improved sufficiently to allow turnout. In this example, the late pregnancy and lactation periods of greatest nutritional demand will be when there is insufficient grazing to provide the energy and protein required, so that supplementary feeding will be necessary. If synchronisation is to be used, there must be sufficient shed space or pasture allocation to allow all the ewes to be in the shed or on the lambing fields at one time. While the duration of lambing is decreased after synchronisation, the manpower required may be higher.

The Ram Effect

Exposure of ewes to the presence and smell of an adult ram can induce ewes in the transition period to begin cycling, if they have been deprived of this contact for the past month. This can advance the breeding period by 3–4 weeks in 60–70% of ewes, and cause synchronisation of 30–40% of ewes. The first oestrus is often silent, and not accompanied by oestrous behaviour. Following this silent oestrus, some ewes have a normal length cycle and some have a short cycle of 4–5 days, where the next oestrus is also silent. The first behavioural oestrus, therefore, occurs in some ewes at around 18 days after first ram introduction, and at around 24 days in the remainder. Vasectomised rams (referred to as teasers) are often used for this purpose. They are introduced for 3–4 days, and are then removed and replaced by fertile rams about 17 days after their first introduction. One adult teaser ram per 100 ewes is generally sufficient. A higher fertile ram‐to‐ewe ratio is required than in the absence of the ram effect, due to the degree of synchronisation. 86 Practical Lambing and Lamb Care

Photoperiod Manipulation

The trigger for ewes to begin cycling is the reduction in the photoperiod of day- light. Manipulation of the lighting period can be used to induce anoestrous ewes to cycle. Ewes need to be exposed to extended photoperiods of 15–18 hours for two months before returning to normal day length. The consequent increased hours of darkness triggers increased melatonin release, and results in a return to reproductive cyclicity. This method requires prolonged housing of sheep, and so is impractical in most settings. It becomes harder to implement at more northerly latitudes, where day length during the summer is longer.

Melatonin Implants

Increased melatonin secretion, due to increasing hours of darkness, is the signal for a resumption of cyclicity in ewes, and increased sperm production and libido in rams. This can be created artificially by the use of melatonin implants inserted subcutaneously at the base of the ear. Melatonin implants can successfully advance the breeding season into the normal period of deep anoestrus. Melatonin implants are most effective when given to both ewes and rams at the same time. Careful planning is required, well in advance of the target date for the start of mating. Rams and ewes should be separated beyond sight, sound and smell from at least seven days before melatonin implantation. The melatonin implants should be inserted between 30–40 days before ram introduction. There is then a delay of 14–21 days before mating activity commences, with a peak of mating 25–35 days after the rams are introduced. There is no synchronisation effect with melatonin implants, but vasectomised rams can be used for the first 14 days to ensure a more compact lambing period. Conception rates to the first mating should be the same as for mating within the normal breeding period, and more than 93% of animals that do not conceive will have a second behavioural oestrus rather than returning to anoestrus.

Reproductive Hormone Manipulation

Hormone manipulation methods may be used to advance the breeding season, to synchronise oestrus, and to increase fecundity. The most appropriate method varies depending on which of these aims is most important, and on whether hormone manipulation is performed during the breeding season, during anoestrus or during the transition period. Progesterone‐releasing intravaginal sponges mimic the hormone profile of the luteal phase (the period of the oestrous cycle between ovulations). Injection of equine chorionic gonadotrophin (eCG) – also called pregnant mare’s serum gonadotrophin (PMSG) – increases levels of follicle‐stimulating hormone (FSH) and luteinising hormone (LH), and so causes ovulation. Sponges are placed into the ewe’s vagina and left in place for 7–14 days. The sponge is then removed, and PMSG is administered to advance and synchronise the breeding season. CHAPTER 4 Head and neck surgery

4.1 Disbudding and dehorning 90 4.8 Enucleation (ocular 107 4.2 Trephination of frontal sinus 97 exenteration) (for empyema) 4.9 Insertion of a nose ring in a 109 4.3 Entropion 100 bull 4.4 Third eyelid ﬂap 101 4.10 Tracheotomy 111 4.5 Eyelid lacerations 103 4.11 Oesophageal obstruction 115 4.6 Ocular foreign body 104 (‘choke’) 4.7 Neoplasia of eyelids 105

4.1 Disbudding and dehorning

Indications • improve stock management • reduce aggressive behaviour towards other members of the herd and stock personnel • reduce traumatic damage/injury

Anaesthesia, analgesia and selection of techniques • in the UK all calves over one week old may only be disbudded or dehorned using anaesthesia or analgesia (Animal Anaesthetics Act 1964) • in some countries (e.g. Switzerland), general anaesthesia is mandatory • disbud at an early age: easier; less risk of infection; no haemorrhage; better animal welfare • cornual nerve block is described in Section 1.9 • post-operative analgesia (NSAIDs) strongly recommended

Bovine Surgery and Lameness, Third Edition. A. David Weaver, Owen Atkinson, Guy St. Jean and Adrian Steiner. © 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/weaver/bovine-surgery Head and neck surgery 91

Chemical cautery • may be suitable for very young calves (<1 week old) • local caustic compound (NaOH, KOH, collodion) applied to horn buds • wear protective gloves • clip hair from the horn buds, protect the surrounding skin with petroleum gel and apply a thin film of paste • confine calves afterwards for 30 minutes • use of caustic preparations is hazardous and forbidden in some countries Surgical and heat cautery • ideal age for surgical disbudding is one to two weeks old, when the horn buds project 5–10 mm, are easily palpable and a disbudding iron can be used alone (see Figure 4.1) • hot irons suitable for larger horns may be free standing with large copper heads (heated in a naked flame gas burner) or connected via a regulator and gas pipe to a portable butane/propane gas supply • disbudding of young calves (<6 weeks old) has become much easier since the advance of portable hot gas or electric irons, butane gas-powered

Figure 4.1 Two disbudding and dehorning instruments (not to scale). A. Head of electrical or gas-powered calf disbudding iron; B. head of Barnes dehorner; C and D are cross-sections of the effect in C of burning a circular trough around the bud and in D the blades cut away the horn and rim of the adjacent skin. 92 Chapter 4

dehorners (e.g. PortasolTM gas dehorner mark 3; Gas BuddexTM) and rechargeable electric irons (e.g. Dairymac SteribudTM; Horn’upTM) • from 1 to 4 months old (horn length 3–5 cm) a Barnes dehorning gouge (see Figure 4.1), Roberts dehorning trephine, or double-action hoof shears may be applied, followed by a disbudding iron for haemostasis • older animals (older calves, yearlings, adults) are dehorned either by embryotomy (Gigli) wire, Barnes gouge, dehorning (butcher’s) saw or dehorning shears

Restraint • a purpose-built calf disbudding crate is best for both operator and patient: holds the calf and head securely; superior models include a belly support • manual restraint of calf: hindquarters in a corner and head held with ﬁngers placed below the jaw; assistant leaning against the shoulder region; halter advised for larger calves • calves may be adequately handled in pens, a group of 10–20 being blocked and marked in sequence before carrying out the dehorning • xylazine may be used in addition to local anaesthetic (see Section 1.9) • stock over six months (>200 kg) will require a crush/chute and a halter

Technique of disbudding • place the hot disbudding iron on the bud and rotate several times, angling the instrument so that the edge burns the skin around the periphery of the bud to include adequate germinal epithelium (see Figure 4.1) • press down on the instrument, scoop and ﬂick off the horn bud, leaving a crater, in the middle of which is a residual small cartilaginous protrusion, which may be left since it is not germinal epithelium • operate on older calves by placing the Barnes dehorner blades precisely around the base of the horn bud and removing a small (3–5 mm) strip of skin at the same time as the bud is guillotined off. Achieve haemostasis with the hot disbudding iron • alternatively, remove horns as short as 5 cm rapidly with embryotomy wire (more physical effort but minimal haemorrhage due to the heat)

Tip

Removing the skin at the centre of the horn bud is not strictly necessary as long as the full thickness of skin is cauterised around the periphery. However, removing the central skin is a practical method of ensuring adequate cautery: too little and the horn will grow; too much time/ pressure applied and bone necrosis may occur ± brain damage Head and neck surgery 93

Figure 4.2 Position of the cow’s head and of the dehorning shears (Keystone) or saw. Note that the haltered head is pulled forwards and to the side away from the crush gate, the cutting angle should be 30–45° and the blade or wire is placed on to the skin of the horn–skin junction.

Technique of dehorning • sedation recommended • cornual nerve block (see Section 1.9) • for mature cattle (>18 months), inject additional 5–10 ml l.a. s.c. at the caudal base of the horn to block significant innervation from the first cervical nerve • wait 10 minutes; then check with a needle that skin adjacent to the horn is painless • ensure adequate restraint of the head in the gate of the crush and position the head (halter) so that considerable traction can be exerted on an embryotomy wire during sawing (see Figure 4.2) • if using a saw, ensure the head is restrained so the operator is safe yet access to the medial aspect of the horn is possible • wire: the first cut is made with wire on the caudolateral aspect; ensure the direction is caudolateral to the craniomedial; change of direction is difficult midcut • saw: a cut can be made medial to lateral • place the wire and saw so that the instrument passes through skin about 1 cm from the skin–horn junction 94 Chapter 4

• blade or wire should emerge dorsally through the skin lateral to midline of the poll. In Friesian/Holstein cows residual width of midline skin should be 5–8 cm • avoid interrupting the sawing movement in the middle of the dehorning process • relatively narrow diameter horns (<5 cm) may be removed by a long- handled dehorning gouge (Barnes pattern). This instrument may also be useful in trimming off additional protruding lips of horn where the initial procedure has been too conservative

Discussion • In yearling and adult cattle the preferred method is embryotomy (obstetrical, Gigli) wire, disadvantages being the physical effort and relatively slow speed. Advantages include neat appearance and less haemorrhage. • The saw method is more unsightly and control of haemorrhage takes longer. • Dehorning shears (e.g. Keystone dehorner) is the most rapid method but causes considerable haemorrhage. A major dis advantage is that a sudden violent head movement during closure of the guillotine blades can cause a shear fracture of the frontal bone and secondary wound problems including frontal sinusitis.

Haemostasis • preferred method: torsion or torsion/traction on the 2–3 major vessels in the medial aspect (ventral crescent) of the peripheral skin; easily identiﬁed and picked up by haemostatic forceps; six to eight turns • rubber tourniquet or string around the horn base applied in a pattern to exert pressure also on dorsal horn border • if the horn is removed too high up: wooden toothpicks can be pushed into the bone canal, from which considerable blood can spurt (remove the toothpick the next day) • cautery, e.g. hot iron: often ineffective by itself, particularly with large horns • liberal use of bacteriostatic (e.g. sulfanilamide; not licensed in the EU) or haemostatic wound powder (Fe salts, tannic acid, alum) • check dehorned cattle 2, 12 and 24 hours after surgery for any recurrence of bleeding, which may result from local irritation and pain leading to rubbing the cut surface against a wall Head and neck surgery 95

Warning

Do not expect heat from embryotomy wire to be sufﬁcient alone to achieve adequate haemostasis; the effect will be temporary only.

Technique of cosmetic dehorning • used in show cattle in North America • gives an improved appearance following surgery, as the wound is closed by apposition of skin edges over the horn base • carried out aseptically with the aim of primary healing; a sterile paper drape is optional • should decrease the risk of post-operative sinusitis • clip a skin band 8 cm wide over the poll and around each horn base; surgical skin preparation • cornual nerve block (Section 1.9) and local analgesic infiltration caudal to the horn base and in midline • make a transverse incision over the poll and laterally in a curved fashion, passing 0.5 cm from the horn–skin junction, the two wounds joining lateral to the horn base and continuing towards the mandibular joint for 5 cm (see Figure 4.3) • undermine the skin peripherally from the incision far enough to avoid skin damage when the horn is removed by a saw or Barnes gouge • avoid auricular muscle laterally • remove more horn if necessary (sterile bone chisel and hammer, Barnes gouge) until the cut is exactly flush with the frontal bone • clean the surface with sterile swabs and effect haemostasis • undermine the skin further to enable edges to be apposed across the bone surface without excessive tension, and check cosmetic appearance; relief incisions are often required • appose edges with interrupted sutures of monofilament polypropylene • clean surface of all blood and debris; apply topical antibiotic • remove sutures in 14 days

Possible complications of disbudding or dehorning • side-effects (excessive salivation, mild ataxia, temporary collapse) caused by an inadvertent i.v. injection of analgesic solution in young calves • failure to remove the horn bud completely in calves (inadequate depth of cautery) results in regrowth or ‘scurs’ 96 Chapter 4

Figure 4.3 Incision and nerve supply for cosmetic dehorning. (A) Rostral view: ‘o’ is the position for the captive bolt gun in euthanasia. (B) Lateral view: 1. zygomaticotemporal nerve; 2. frontal nerve; 3. infratrochlear nerve; -- skin incision.

• in older cattle frontal sinusitis (pneumatisation of the horn starts at eight to nine months) and empyema caused by entry of infection and ﬂy strike in summer and autumn (see Section 4.2) • poor surgical technique results in prolonged local irritation and an increased tendency for the cut surface to be rubbed against dirty surfaces (e.g. soil, bedding, walls) Head and neck surgery 97

Tip • Avoid dehorning in the major ﬂy season (e.g. in the UK from May to late September). • Avoid feeding hay or straw from overhead racks to reduce the risk of frontal sinusitis.

4.2 Trephination of frontal sinus (for empyema)

Indication • frontal sinusitis with pus occupying this multiloculated structure and with chronic discharge through the horn base • post-dehorning infection

Anatomy (Figures 4.4 and 4.5) • the frontal sinus has several compartments: the large caudal frontal sinus is completely divided by an oblique partition into rostromedial and caudo lateral sections • the rostromedial compartment has a narrow nasofrontal opening and a post-orbital diverticulum • the caudolateral compartment has the cornual diverticulum and nuchal diverticulum, which ends by also excavating the parietal, occipital and temporal bones • two or three small chambers lie level with the rostral part of the orbit • the borders of the frontal sinus are from the rostral part of the orbit to a transverse line drawn through the midline of the orbit, laterally to the frontal crest and caudally to the nuchal crest (poll). A midline septum separates the two frontal sinuses • the normal small communication of the frontal sinus with the ethmoid sinus and the nasal cavity is usually occluded due to mucosal thickening and purulent discharge

Clinical signs of frontal sinus empyema • chronic discharge of pus (e.g. from the dehorning wound) • may pass into the maxillary region, sometimes with systemic illness (pyrexia, anorexia, loss of condition, head tilt, localised swelling and pain) • some cases result from horn fracture, usually a direct result of uncontrolled movement of the head during dehorning (poor anaesthesia) • sinusitis often conﬁned initially to the caudal part of the sinus 98 Chapter 4

Figure 4.4 Median section through the head, left half. (From Pavaux, 1983.) 1. caudal frontal sinus; 2. medial rostral frontal sinus; 3. sphenoidal sinus; 4. nasal cavity; 5. nasal septum; 6. hard palate; 7. root of tongue; 8. soft palate; 9. isthmus faucium (oral part of pharynx, oropharynx); 10. nasal part of pharynx (nasopharynx); 11. pharyngeal septum; 12. nasopharyngeal meatus; 13. laryngeal part of pharynx (laryngopharynx); 14. entrance to larynx (laryngeal aditus); 15. vestibule of oesophagus; 16. oesophagus (cervical part); 17. cavity of larynx. X shows the common site of the oesophageal obstruction; the long arrow shows the hand passed into the pharynx and the short arrow the retrograde pressure on oesophageal foreign body.

Restraint, anaesthesia and trephination landmarks • restrain the animal adequately in a crush/chute and give a sedative • clip the hair around the horn base and over the entire frontal region, cleanse and disinfect • produce local analgesia by a supraorbital block (see Section 1.9) or inﬁltration over the site of the proposed trephine opening, located 5 cm dorsal to the line joining the two supraorbital processes and about 5 cm from the midline • further landmark: 2–3 cm abaxial at the level of a horizontal line joining the axial parts of both orbits • sometimes a soft area of bone indicates a suitable site Head and neck surgery 99

Figure 4.5 Diagram of longitudinal and rostral sections through the skull to show the extent of sinuses. 1. frontal sinus; 2. maxillary sinus; 3. position of orbit; 4. rostral compartments of frontal sinus; X trephine sites for empyema of frontal sinus. (Modiﬁed from Dyce and Wensing, 1971.) • a ventral site is preferable if the horn sinus is still patent, permitting ﬂushing from one opening to the other • avoid the supraorbital foramen and vein (see Figure 1.5)

Technique • remove a circular area of skin, subcutaneous tissue and cutaneous muscle 3 cm in diameter using a scalpel and forceps • elevate the periosteum with a periosteal elevator and remove it with the scalpel • trephine the bone over the sinus using a 2.5 cm diameter Galt or Horsley pattern trephine, and remove this bone disc • ﬂush the sinus initially with warm water using an enema pump • insert the enema pump (Higginson’s syringe) to direct an irrigation mixture into the various compartments 100 Chapter 4

• continue irrigation through the horn sinus orifice • irrigate finally with isotonic saline, flushing from top to bottom • pick up any major bleeding points with artery forceps and keep the trephine opening patent for daily flushing by a stock person

Post-op care and possible complications • avoid feeding hay/straw from an overhead rack • in chronic cases, repeated lavage or a permanent through-and-through lavage system may be indicated • the wound usually heals in three to four weeks • parenteral medication (ﬁve to ten days with broad spectrum antibiotics) is indicated in animals with systemic signs and in all long-standing and severe cases • as the trephine opening closes over, continue irrigation with a ﬂexible polypropylene or PVC catheter attached to the syringe; it is helpful to suture the catheter in place • prognosis is favourable (acute cases) to guarded (chronic cases) • infection rarely (but sometimes!) extends to the opposite side of the skull or to the brain

4.3 Entropion

Introduction and signs • low incidence, more common in over-conditioned beef breeds • involves the lower lid more frequently than the upper lid • often bilateral to a varying extent • occasionally congenital, usually acquired (facial skin folds – particularly over-conditioned bulls) • often exacerbated by halters (e.g. show animals) • signs include mild blepharospasm, conjunctivitis, keratitis, and corneal ulceration if not corrected early • rarely resolve spontaneously, progressing to blepharospasm and keratitis

Anaesthesia • linear sub-conjunctival inﬁltration of anaesthetic solution parallel and 2 mm distant to the lid margin

Techniques (a) careful insertion of 3 or 4 stainless steel staples into a horizontal fold of the lower lid is a simple and effective method of achieving eversion Head and neck surgery 101

Figure 4.6 Entropion correction involving the lower lid of the left eye with a skin incision 2 mm below the lid margin.

(b) alternatively the Holz–Celsus procedure is possible: • estimate length and width of skin to be resected by pinching to produce an approximate skin fold to correct inversion of the lid margin • scalpel incision to remove a ridge of skin previously measured (see Figure 4.6) • close the wound margin with a single continuous or mattress absorb able suture e.g. PDS (avoiding the need for later removal) (c) injection of a small volume (e.g. 1 ml) of long-acting antibiotic. The line in the lower lid may effect correction. This technique may allow temporary resolution during a weight-loss diet • complications are unlikely, though under-correction may necessitate second surgery

4.4 Third eyelid ﬂap A suture placed in the third eyelid (nictitating membrane) is passed through the dorsal lateral conjunctival fornix to emerge through the skin. When tightened the third eyelid is drawn across the corneal surface.

Indications • Cases of extensive but superﬁcial corneal ulceration and of traumatic damage, often when antibiotic medication has failed to achieve early resolution of the lesion. 102 Chapter 4

Figure 4.7 Third eyelid ﬂap in the right eye. The shaded area is the third eyelid (A) sutured into the dorsolateral fornix, (B) by a suture through the skin and (C) supported by a 1.5 cm long plastic stent (D). Note that the suture does not penetrate the full depth of the third eyelid and therefore does not contact the corneal surface.

Techniques (Figure 4.7) • inject 2 ml of local anaesthetic into the third eyelid, which is grasped by ﬁne Allis tissue forceps, and then 5 ml into the area of skin sutures • thread PGA (Dexon®) or PDS 0 gauge suture material into a half-curved cutting needle • grasp the edge of the third eyelid with Allis forceps again and place the suture through the palpebral surface of the lid about 5 mm from the edge. The suture should not penetrate the bulbar surface of the third eyelid (as this could cause subsequent corneal abrasion) • now insert each end of the suture in turn through the lateral dorsal conjunctival fornix to emerge through the skin about 2–3 cm above the lateral commissure of the eyelids • insert 1 cm of polypropylene stent on to the suture over the skin, and tie in a ‘quick release’ fashion with sufﬁcient tension so that the third eyelid covers the entire visible surface of the cornea, including the lesion • inspect the eyelid suture daily (stockperson), apply any local medication and possibly slacken off the suture to inspect the cornea in order to assess the healing process • leave the suture for two to three weeks, then remove with scissors

Possible complications • early tearing out of the suture from the third eyelid (insufficient tissue ‘bite’) • failure to pull the flap sufficiently laterally (incorrect placement) • tearing out of sutures through the skin due to the absence of a stent Head and neck surgery 103

• mechanical irritation of the corneal surface from the suture material (suture perforating the entire depth of the third eyelid, or is too slack, failing to pull the third eyelid completely across the cornea)

Discussion

No comparative studies are available on the success of this simple technique. Results are generally good as the bovine cornea heals well.

4.5 Eyelid lacerations

Introduction • The upper or lower lid is sometimes torn following injury from a projecting nail, piece of metal or gate hinge • sometimes a strip of the lower eyelid hangs down and the extent of the loss of the lid margin is very variable • repair is urgently needed but initially the cornea should be carefully examined for damage

Restraint and clinical signs • ﬁrm restraint in the crush with a halter applied • topical anaesthesia and regional s.c. local anaesthesia • consider xylazine for sedation • examine the extent of the injury and check for any foreign bodies on the cornea and beneath the lids • many lacerations are contaminated with vegetable matter and bleed profusely if seen shortly after an accident • insert two drops of ﬂuorescin dye to help identify a corneal laceration

Technique of repair • do not trim off the strips of damaged eyelid, unless obviously non-viable; rub gently with a dry gauze swab to identify viable tissue • do not clip the surrounding hair, since it is impossible to avoid hairs going on to the corneal surface, which leads to further trauma • appose skin edges using figure of eight interrupted sutures (simple inter rupted cruciate pattern) with fine (5-0) vicryl • sutures should never contact the corneal surface • maintenance of an intact eyelid margin is vital, so the first suture should precisely appose the eyelid margin, incorporating the firm tarsal plate and the orbicularis oculi muscle, which aids good wound apposition 104 Chapter 4

• regular spraying with normal saline maintains clean ﬁeld for sutures • if the corneal surface is damaged, topical broad-spectrum antibiotics should be applied every few hours on the ﬁrst day, and a least twice a day for a further week

Possible complications • primary complications: dehiscence; suture rubbing on the cornea; ulcer not healing (if damaged cornea) • secondary complications: trichiasis from irritation caused by eyelid hairs; exposure keratitis (poor tear ﬁlm over the cornea) and chronic keratoconjunctivitis • severe lacerations may require to be stented with the sutured lid being sutured to the opposing eyelid, and a trans-palpebral ocular lavage system built in for easy application of medication

4.6 Ocular foreign body

Indications and signs • foreign bodies such as particles of chaff, burrs and thorns may lodge on the corneal surface, particularly in the lateral or medial canthus, and provoke a keratoconjunctivitis • signs are obvious in recent cases with epiphora, ptosis, blepharospasm and discomfort • chronic cases show corneal scarring and pigmented keratitis • material may often be removed without local analgesia • differential diagnosis includes conjunctivitis, iritis and uveitis

Techniques of removal • place the animal in a chute with a halter attached; consider sedation • suitable topical analgesics include amethocaine, xylocaine or proparacaine • hold the head firmly and tilted in good light so that material is in midfield of the orbital fissure • spray sterile saline through a 22 gauge needle hub tangentially at the foreign body in an attempt to dislodge it • if unsuccessful then attempt removal with fine dissecting forceps or with a fine flat surface such as the blunt surface of a large scalpel blade • assess superficial corneal damage subsequent to foreign body removal, following installation of one to two drops of fluorescein stain • insert a topical broad spectrum antibiotic (e.g. cloxacillin) four times daily for three days after removal, or inject a subconjunctival antibiotic depot Head and neck surgery 105

• topical 1% atropine b.i.d. or to effect will maintain pupil dilatation; cortico steroids are contraindicated as they hamper repair of any residual ulcer

Prognosis • good, unless secondary infection is present, or secondary endophthalmitis has resulted from deep corneal perforation

4.7 Neoplasia of eyelids

Introduction • most common neoplasm of the upper or lower lids and nictitating mem brane (third eyelid) is squamous cell carcinoma (SCC) (‘cancer eye’) • rarely, other tumours, such as papillomata, and ﬁbrosarcoma • SCC is most important in terms not only of incidence but also of economic importance and prognosis, especially in South West USA; the most com mon malignancy in cattle • SCC is very invasive locally and may metastasise to the local lymph nodes (parotid, atlantal or retropharyngeal and the anterior cervical chain)

Warning

It is illegal in some countries to transport cattle with large (> 2 cm diameter) ocular tumours. In EU countries, generalised neoplasia renders the whole carcass unﬁt for human consumption. Quick action is advised with ocular neoplasia.

Clinical signs • SCC is particularly common in Hereford and Simmental breeds and their crosses; approximately 85% of cattle with SCC lack pigment in the affected area • the non-pigmented area is liable to develop neoplastic lesions under the inﬂuence of ultraviolet radiation from sunlight; there is often a precursor lesion • affected cattle are usually four to nine years old • lesion is often a proliferative irregular mass that may ulcerate through the skin and cause distress and blepharospasm • early lesions appear either as rice-grain-like plaques on the sclera or corneal surface (which may regress), or as small ﬁrm nodules in the periocular dermis; this precursor of a greyish-white plaque at the nasal and temporal limbus develops into a papilloma and carcinoma in situ 106 Chapter 4

• lid lesions often start as pale brown, horn-like teratomata • differential diagnoses include ocular foreign body, traumatic injury and iritis

Treatment • treatment is indicated in early lesions with no evidence of secondary spread either to adjacent structures (e.g. bone) or metastases to the drainage lymph nodes • Several techniques are available and include: a. excisional surgery b. cryotherapy c. hyperthermia d. radiotherapy (rare) e. immunotherapy (rare)

(a) Excisional surgery of third eyelid • sedation advised • in a standing or recumbent animal induce analgesia by local anaesthetic inﬁltration of the base of the eyelid after instilling a topical anaesthetic solution (e.g. 0.5% proparacaine) into the conjunctival sac • draw the third eyelid out by traction with forceps • excise the eyelid as deep as possible to cartilage with curved scissors • control haemorrhage with an adrenaline-soaked swab, or cryotherapy

(b) Cryotherapy • cryotherapy is particularly advantageous since it avoids haemorrhage and is simple and relatively fast • a small liquid nitrogen ﬂask (e.g. Nitrospray®) is adequate for lesions up to 5 cm in diameter and 1 cm deep • protect the globe from inadvertent freezing by inserting ‘Styrofoam’ strips or acrylic between the lid and corneal surface; apply water-soluble lubri cants or vaseline to surrounding healthy skin • clip and wash the affected area; wear latex gloves • freeze the area twice (liquid nitrogen) or three times (nitrous oxide, carbon dioxide) initially using a spray tip • freeze at least a 5 mm width border of clinically healthy tissue • evert tissue lying close to the cornea by grasping with towel clips or Allis tissue forceps, before applying a probe head to deal with lesions of the third eyelid • use thermocouples if available, inserting points 5 mm from the margin of lesion and stopping freezing when they indicate a temperature drop below 20 °C Head and neck surgery 107

• disadvantages of cryotherapy are: lesions > 2.5 cm diameter require relatively prolonged application of a probe head for complete ice-ball formation; lesions exceeding 5 cm must be treated in two stages, or involve an initial surgical debulking procedure

(c) Other techniques • radiofrequency hyperthermia: involves application of heat (50 °C for 30 seconds) to various surface points of the tumour and surrounding skin using a probe head; penetration is limited to 0.5–1 cm only • radiotherapy: radon and gold seed implants have both been successfully used in valuable cattle; penetration again only to 0.5–1 cm • immunotherapy: local inﬁltration of the mycobacterial cell wall fraction (Regressin-V®, no longer commercially available)

Possible complications • recurrence possible: failure or inability to remove all the neoplastic tissue (SCC) • wound breakdown

4.8 Enucleation (ocular exenteration)

Indications • ocular neoplasia • gross damage to the bulb, usuallywith severe primary or secondary infection • trauma or rupture of the globe, resulting in anterior staphyloma or panophthalmitis, and a risk of ascending infection up the optic stalk • enucleation (removal only of the globe) is rarely indicated in cattle; as a cosmetically satisfactory appearance it is not as important as in equines and small animals; exenteration (removal of the globe and orbital contents) is more common

Restraint and anaesthesia • anaesthesia: GA if possible • alternatively standing or recumbent under xylazine sedation and Peterson or retrobulbar block (see Section 1.9) • or ophthalmic nerve analgesia and local inﬁltration of the lower lid and medial canthus

Technique of ocular exenteration • clip, cleanse and disinfect peri-orbital area • place continuous suture through the upper and lower lids 108 Chapter 4

Figure 4.8 Exenteration of the eye (longitudinal diagrammatic section). Dotted line (A) starts in the lids, passes through the peri-orbital structures and results in removal of the globe, all orbital contents, eyelid margin and conjunctiva. B. optic nerve and vessels; C. muscles. Shaded areas above and below are frontal and zygomatic bones. • perform lateral canthotomy (2 cm) to aid exposure of peri-orbital tissues • using traction with towel clips or Allis tissue forceps, make a circumferen tial incision 1 cm from the skin–conjunctival junction, or as appropriate depending on the distribution of non-viable or neoplastic skin (see Figure 4.8) • continue towards the orbital ridge down to, but not through, the conjunctiva • exerting some digital traction on eye muscles, dissect the extraocular muscles bluntly with Mayo scissors from the lateral and medial canthus • avoid excessive traction on the optic nerve (risk of vagal nerve stimulation and damage to optic chiasma) • grasp the eyeball and use further gentle traction to dissect it free from surrounding retrobulbar tissue (excluding the conjunctival sac) and optic nerve Head and neck surgery 109

• if SCC, remove as much retrobulbar tissue as possible • clamp the ophthalmic vessels, optic nerve and retractor bulbi muscle with slightly curved, long-handled artery forceps (Roberts 23 cm or Kelly 25 cm); ligate vessels with 7 metric chromic catgut (difficult: not essential) • the third eyelid and Harderian gland will also be removed • check the site for complete removal of all neoplastic or infected tissue • meticulous haemostasis during enucleation is time-consuming and in most cases not necessary • pressure pack the orbital space for a few minutes with sterile gauze swabs; remove and irrigate with aqueous antibiotic solution (20 ml) • re-pack with a scrunched-up gauze bandage soaked in antibiotic, leaving a free end to protrude from the wound • alternatively, insert absorbable gelatine sponges • appose skin edges of lids using a simple continuous suture pattern (mono filament nylon) • leave the free end of the bandage packing (pressure haemostasis) protrud ing from one end of the wound • administer systemic antibiotics for five to seven days, NSAIDs for three days, and tetanus prophylaxis as required • insertion of a drain is rarely indicated • remove the gauze bandage packing by pulling the free end gently after 2 days; this may be done in stages (i.e. half removed after 2 days and the remainder after 2 further days) • remove the sutures two to three weeks later • the resulting ankyloblepharon is cosmetically acceptable. Some cows become more nervous due to a restricted field of vision

Possible complications • failure or inability to remove all neoplastic tissue (SCC) • massive intraorbital haemorrhage • abscess formation • excessive dead space, and failure to appose the skin margin without excessive tension on sutures: relieving sutures may help

4.9 Insertion of a nose ring in a bull

Introduction • a ring is used to aid restraint and control of a bull when being moved or in the show ring • it is inserted into the soft tissue of the nasal septum immediately cranial to the cartilaginous septum • a stock bull should have his ring inserted from 10 to12 months old 110 Chapter 4

Restraint • confine the bull to a crush; sedation advised • always apply a halter and firmly restrain to a fixed object (not a person) • local anaesthetic injection is not helpful; some local anaesthesia via mucosal absorption is possible: hold cotton-wool soaked in procaine against the nasal septum. Wait 5 minutes

Warning

Take particular care working around adult stock bulls; each year several injuries and deaths are reported in the UK alone due to stock bulls. Common injuries include crushing and head trauma (e.g. frac tured skull) resulting from being knocked over by the swipe of a bull’s powerful head. This is far more likely than being charged.

Technique of insertion • the septum must be punctured prior to inserting the sharp end of the open ring • use a made-for-purpose bull ring hole punch (strongly advised) • make a hole for the ring approximately 2–3 cm in, through the cartilagi nous part of the septum • a metal trocar and cannula can be used as an alternative: forced in one movement through the septum and the trocar is removed; the pointed end of the ring is placed into the cannula which is then slowly withdrawn so that the ring emerges through the wound • once in place, the ring is quickly closed, and the screw inserted and turned rapidly • smooth off the surface of the screw and the hinge section with sandpaper if necessary; most rings now incorporate a screw where the head can be snapped off so it is ﬂush with the ring • systemic antibiotics are usually not required but there is a small risk of tetanus

Tip

The small nose-ring screw is easily lost on the ground. Either attach a length of ﬁne, coloured cotton on to the screw to ease detection if dropped or carry a spare. Head and neck surgery 111

Possible complications • a nose ring is designed to last a lifetime • if pulled out accidentally, as when caught on a sharp pointed object (e.g. fencing) then a nasal septum can potentially be repaired by careful surgery and heals after 4–6 weeks • repair should be done as soon as possible, as granulation tissue develop ment will hinder surgery • it is unlikely that a repair will be strong enough for a new ring; possibly a larger ring, inserted more caudally in the septum, may be used

4.10 Tracheotomy

Introduction • necrotic and purulent laryngitis is caused by Fusobacterium necrophorum infection and Trueperella pyogenes abscessation respectively, or may be secondary to intra- or retrolaryngeal foreign bodies or other mechanical irritants (dust, repeated coughing due to other pathogens) • indications for tracheotomy rarely involve pharyngolaryngeal neoplasia, retropharyngeal abscessation, foreign bodies in the upper respiratory tract, or persistent laryngospasm • surgical conditions of head involving haemorrhage and potential aspira tion of blood and infected tissue should be managed with an endotracheal tube in position • the tube should only be removed after the return of a cough and swallow reﬂexes

Clinical signs • signs indicative of the need for tracheotomy, often an emergency proce dure, include progressive dyspnoea, stridor, and mild cyanosis • some animals have fetid breath (F. necrophorum) and pharyngeal lesions, which can be both seen and palpated • a mouth gag should be inserted and a long-bladed laryngoscope or endo scope used to aid examination

Anatomy • tracheal rings are readily appreciated on deep palpation of the upper part of the neck • diameter is narrow compared with equine trachea • depth is slightly greater than width 112 Chapter 4

Figure 4.9 Cross-section of the neck at the level of the ﬁfth cervical vertebra, ventral part, looking caudally. 1. trachea; 2. oesophagus; 3. right common carotid artery; 4. right external jugular vein; 5. right internal jugular vein; 6. right vagosympathetic trunk; 7. right recurrent laryngeal nerve; 8. left common carotid artery; 9. left external jugular vein; 10. left internal jugular vein; 11. left vagosympathetic trunk; 12. left recurrent laryngeal nerve; 13. sternohyoid and sternothyroid muscles; 14. sternocephalic muscle; 15. brachiocephalic muscle. (From Pavaux, 1983.)

• trachea is related at the junction of the upper and middle thirds of the neck to the oesophagus on the left side, and to the carotid sheath, enclosing the common carotid artery, vagosympathetic trunk and inter nal jugular vein on the right and to a lesser extent on the left. It is deep to the distinct and bulky sternomandibular and the ﬁner sternothyrohyoid muscles, which are ﬁne muscular bands on the ventral tracheal surface (see Figure 4.9, which is a cross-section somewhat distal to the preferred tracheostomy site)

Restraint and anaesthesia • perform surgery preferably on a haltered animal in a crush with the head and neck extended • sedate with xylazine only if necessary: not animals with signs of severe cardiovascular and respiratory dysfunction • local s.c. inﬁltration of the surgical site with local anaesthetic Head and neck surgery 113

Technique • keep the head and neck extended • identify the midline in the upper third of the neck at the level of tracheal rings 4–6 • clip and disinfect the skin over this area and make a 6 cm longitudinal incision through the skin and subcutis directly over the tensed trachea • separate the paired sternomandibular muscles in the midline by blunt dissection, followed by sternothyrohyoid muscles • insert a self-retaining wound retractor (West or Gossett model): not essential • temporary tracheotomy tube: incise the tracheal annular ligament; do not incise tracheal rings • insert the tracheal tube; various models are available. In a calf the maximum diameter may be 13 mm; these are commercially available. Some tubes are up to 14 mm in diameter (Portex Blue Line®) and have external tapes for ﬁxation • anchor the tube to the skin at two points to prevent rotation. Tie loosely to allow removal for cleaning • permanent tracheotomy tube: resect two half-moon shaped segments of adjacent tracheal rings corresponding to the size of the tracheal tube (see Figure 4.10). This form of tracheal incision maintains the tracheal lumen, which can otherwise collapse when incision involves an entire cranio caudal section of ring • use an equine steel tracheotomy tube (see Figure 4.11) with an internal diameter of 22 mm (Kruuse veterinary products)

Figure 4.10 Diagram of a tracheostomy incision to show a portion of two adjacent rings resected to permit insertion of a tracheotomy tube. 114 Chapter 4

Figure 4.11 Stainless steel or nickel-plated brass tracheotomy tube (internal diameter 22 mm; external diameter 28 mm).

• insert one half and then thread the second part through the first; the fitting is usually tight and brings the trachea close to the skin • suture in place (nylon), though a tight fit usually secures it in place

Warning: Risk of Tracheal Collapse

The C-shaped cartilage rings are completed dorsally by a ﬂexible ligament; hasty section of the rings ventrally will result in a collapsing trachea under negative pressure during inspiration unless held open by a tracheotomy tube. Although often acute in onset and requiring rapid treatment, it may be preferable to treat laryngeal obstruction medically initially (e.g. corticosteroids) unless a permanent tracheotomy tube is immediately available (Figure 4.11).

Post-operative care • silicone temporary tracheotomy tubes require frequent (minimal twice daily) cleaning of both the tracheal lumen and external surface • the relative quantity of debris and inﬂammatory discharge is greater than in horses • skin scalding by exudate is reduced by petrolatum jelly (petroleum jelly or VaselineTM) • remove the tube after alleviation of the primary condition, which may require systemic antibiotics alone, or combined surgery (drainage of the laryngeal abscess in calves) and antibiotic therapy and NSAIDs • do not suture the tracheal or skin wounds • avoid hay dust in the immediate environment to reduce possible iatrogenic bronchopneumonia Head and neck surgery 115

Possible complications • a major complication is the extension of granulation tissue from the wound margin to partially occlude the tracheal lumen. Resect proliferative tissue by electrocautery • the prognosis for cattle requiring tracheotomy should always remain guarded

Discussion

Temporary tracheotomy tubes are very difﬁcult to manage success fully, and swelling/chondroma formation after removal can cause tracheal stenosis and severe dyspnoea. Complete relapse and death is not uncommon. A temporary tracheotomy tube will necessarily have a restricted diameter because the cartilage must not be cut prior to insertion. They are more suitable for smaller (<200 kg) animals. A permanent tracheotomy using a metal equine tube is more likely to be successful in a heavy beef animal until it can be slaughtered for human consumption. Tubes may stay in place with little maintenance for approximately six months.

4.11 Oesophageal obstruction (‘choke’)

Aetiology and signs • usually due to round or irregular pieces of food material, e.g. potato, turnip or sugar beet, rarely to sugar beet pulp (cf. horse) • copious salivation and rumen bloat are the most obvious signs • bovine rabies or tetanus sometimes present with similar signs • often can be relieved by medical means (e.g. tranquilizers such as pheno thiazine derivatives, relaxants) and manual retrograde manipulation • site of obstruction is usually the proximal cervical oesophagus, often in the ﬁrst 20 cm (see Figure 4.4); rarely the distal cervical or thoracic oesophagus • distal thoracic oesophageal obstruction is sometimes seen in calves due to swallowing of stomach feeders following oral rehydration therapy • oesophageal obstruction causing recurrent bloat (but not usually saliva tion) can result from external compression (thymic lymphosarcoma, mediastinal lymphadenopathy, e.g. calves with pneumonia) and neuro genic dysfunction (rabies, tetany) • rarely life-threatening as long as care is taken to control development of rumenal tympany: insert a temporary rumenal canula 116 Chapter 4

Tip

Most cases of choke (obstruction) from feedstuffs will resolve sponta neously within 24 hours due to softening from saliva. Insert a rumen trocar and cannula to create a temporary rumen ﬁstula, which will avoid life-threatening rumen tympany. This conservative approach is recommended over passing a pro bang or other tubing, which may cause oesophageal tear or rupture.

Warning

Oesophageal surgery in the ﬁeld should be an absolute last resort: the oesophagus is not a forgiving tissue for surgery and the prognosis is always very guarded. Oesophagotomy is in any case only practical in proximal two-thirds of the cervical part, where the organ is relatively accessible.

Surgical techniques of oesophagotomy • identify the site of obstruction and, if not palpable, ascertain by gently passing a stomach tube • delay radical surgery a minimum of 24 hours, pending medical relief (e.g. xylazine) • perform surgery under GA or with a sedated animal in right lateral recumbency with good head restraint • infiltrate a local anaesthetic solution after routine skin preparation • perform surgery with strict aseptic precautions • the oesophagus lies in deep fascia to the left of the trachea and overlaid by the left jugular vein and the carotid sheath enclosing the carotid and vagosympathetic trunk • keep tissues tense and the surgical field convex, elevated by an underlying pad or manually by a sterile assistant, and attempt again to move a foreign body retrograde into the pharynx • incise the skin to an adequate length (twice the length of the foreign body) and bluntly dissect down to the oesophageal wall • carefully identify and reflect the jugular and carotid trunk dorsally • incise the thin oesophageal wall longitudinally, preferably in an undamaged section, and carefully remove the obstruction, using gauze swabs to avoid surgical field contamination by saliva and food debris • close the oesophageal wall (unless necrotic) with simple interrupted absorbable sutures • place sutures 5 mm apart through the mucosa and muscularis Head and neck surgery 117

• over-sew the muscularis in the second layer of simple continuous PGA sutures, including fascia for increased strength • irrigate the area well with sterile saline before routine skin closure • insert a Penrose drain along the external oesophageal wall to emerge at the ventral (caudal) commissure of the skin wound in cases where contami nation is thought likely to result in infection and secondary healing • systemic antibiotics for 5 days, tetanus prophylaxis • remove the drain after 48 hours • do not suture the oesophagus in cases of full depth mural necrosis, but leave as an open ﬁstula with a supplementary drain • though lying adjacent to the oesophagus, it should be easy to avoid damage to the common carotid artery (dorsolateral) and jugular vein (ventrolateral) • a distal oesophageal obstruction (broken stomach feeders, see above) is treated by removal via rumenotomy

Possible complications • always a guarded prognosis • it is difﬁcult to ensure the primary healing of an oesophageal incision, but chances are improved by keeping the animal on ﬂuids for two days, followed by three days of mash and short-cut fodder • post-operative oesophageal stricture may occur