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VETcpd - Ophthalmology Peer Reviewed

Ocular manifestations of systemic disease in A wide range of systemic diseases affect the eyes in all species, including cats. As the eye can be examined so readily, it is invaluable to be able to recognise ocular signs that can provide an early, rapid diagnosis and accessible evaluation of therapy success. Systemic diseases in cats that can affect the eye include infectious (viral, bacterial, protozoal, fungal and parasitic) and non-infectious (cardiovascular, metabolic, neoplastic and nutritional) conditions. In particular, cats presenting with bilateral ocular disease should be always be carefully evaluated for such diseases, starting with a thorough clinical examination. The clinician should be familiar with endemic infectious diseases, but with increased movement of throughout the world, Natasha Mitchell cats with non-endemic infections can present after travelling. MVB DVOphthal MRCVS Key words: Eye, Ocular, Feline, Systemic Diseases, Systemic Hypertension, FHV-1 Veterinary Council of Ireland Recognised Specialist in Infectious diseases Veterinary Ophthalmology to reduce the severity of clinical signs in Viral infections After graduating from University College cats experimentally infected with FHV-1 Dublin in 1998 with a degree in Veterinary Feline herpesvirus-1 (FHV-1) is a at a dose of 90 mg/kg q8h (Thomasy et al. Medicine, Natasha obtained the RCVS very common pathogen causing both 2011), but clinical improvement has been Certifi cate in Veterinary Ophthalmology in upper respiratory tract and ocular disease. seen at lower doses. However, there is a 2004. She later joined the Eye Veterinary Primary infection commonly causes concern about resistance developing to Clinic in Herefordshire where she completed conjunctivitis (Figure 1). The can the drug, and therefore the recommended an alternative residency programme for the replicate in the corneal epithelium, dose is 90mg/kg twice daily. Oral L-lysine RCVS Diploma in Veterinary Ophthalmology causing dendritic ulceration, which is at 500mg PO BID in adults and 250mg which she obtained in 2011. She is a pathognomonic for FHV-1 infection BID in is thought to limit FHV-1 Veterinary Council of Ireland recognised (Figure 2). Recrudescent infection occurs replication as this amino acid reduces the specialist in Veterinary Ophthalmology. in some latently-infected cats. This presents uptake of arginine, which the virus needs Natasha has published journal articles with milder conjunctivitis, dendritic in order to replicate. However, there is and textbook chapters, as well as creating or geographic corneal ulceration, and little evidence of its benefi ts. There is a education apps in veterinary ophthalmology. stromal keratitis. Ocular disease syndromes recent review of treatment options (Maggs She has published ‘Caring for a Blind ’ associated with FHV infection include and Thomasy 2016). and is the co-author of the textbook ‘Feline ophthalmia neonatorum, symblepharon Ophthalmology – The Manual’. Natasha can result in feline (Figure 3), proliferative (eosinophilic) kera- runs a referral veterinary ophthalmology infectious peritonitis (FIP), and ocular titis (Figure 4), keratoconjunctivitis sicca, service, Eye Vet, in Limerick, Ireland. manifestations have been reported in 36% corneal sequestration (Figure 5), anterior of cats with the non-eff usive (‘dry’) form E: [email protected] uveitis and periocular dermatitis (Figure 6). (Andrew 2000). The most common sign www.eyevet.ie Testing for FHV-1 is controversial as the is anterior uveitis, as immune-complex condition is so widespread that the pres- deposition in the iridal blood vessels ence of the agent does not give conclusive results in breakdown of the blood-ocular evidence of the cause of disease, and many barrier. Typically, there are multiple keratic tests don’t distinguish vaccine virus from precipitates with fi brinous exudates in natural virus. Treatment of conjunctivitis the anterior chamber along with iritis due to FHV-1 infection is usually sup- (Figure 7). Chorioretinitis and vasculitis portive such as a lubricating eye gel, ideally of the retinal vessels may also be seen. containing hyaluronate, which helps Neurological signs may also be present with comfort and goblet cell defi ciency. if there is central nervous system (CNS) Occasionally topical treatment causes involvement. The prognosis is poor but more stress which is counterintuitive. If symptomatic ocular treatment for uveitis secondary bacterial infection or corneal can improve the condition temporarily. ulceration is present, the use of a topical broad spectrum is indicated, such (FeLV) can aff ect as fusidic acid or chloramphenicol. Topical the pupil as infl ammation or tumour infi l- and systemic antiviral medications may be tration of autonomic nerves controlling For Ophthalmology Referrals in useful with initial infection when there is pupil size can result in mydriasis (‘spastic your area: vetindex.co.uk/eyes accompanying upper respiratory tract dis- pupil syndrome’), or a D-shaped pupil ease. Systemic famciclovir has been shown if one of the two short ciliary nerves is

Page 44 - VETcpd - Vol 3 - Issue 2 VETcpd - Ophthalmology affected. FeLV-induced lymphoma may be Feline poxvirus infection is fairly further investigation depending on the evident as a focal or more diffuse swelling uncommon, but usually begins by affecting initial results. PCR can be done on fixed of the iris (Figure 8), or with neoplastic the face and paws before spreading to the samples. There are zoonotic implications, changes in the fundus. The virus can cause rest of the body. Kittens and immuno- even with the biopsy samples. Treatment anaemia or thrombocytopenia, which compromised animals are most commonly is with surgical removal of small skin can also affect the eyes (see later). It can affected. There is no specific treatment and nodules and prolonged multiple antibiotic also cause retinal dysplasia in the case of most animals will recover with supportive therapy (for 6-9 months). There is a better in-utero infection. therapy alone. prognosis for feline leprosy but a poor prognosis for tuberculosis and oppor- Feline immunodeficiency virus (FIV) Bacterial infections tunistic (non-tuberculous) mycobacterial causes ocular signs in some infected infections. Euthanasia is sometimes cats. The most common signs are mild Chlamydophila/Chlamydia felis is Figure 1: A young with symptoms of cat flu Figure 5: A focal corneal sequestrum present in an important cause of conjunctivitis in Figure 9: Uveitis in an FIV-positive cat (which may carried out in preference to treatment for chronic conjunctivitis and, in a few cases, due to FHV-1 infection. Apart from the upper respira- the central cornea, secondary to FHV-1 infection, be caused by FIV infection) with conjunctivitis, cats, and most typically causes bilateral public health reasons. anterior uveitis (Figure 9). Intermediate tory tract signs, there was conjunctivitis and the left causing keratitis with neovascularisation, and small keratic precipitates, pronounced iridal pronounced chemosis and a mucopuru- uveitis (pars planitis) has been associated eye had corneal oedema due to a corneal ulcer there is purulent ocular discharge hyperaemia and dark nodules within the iris Protozoal infections with FIV infection and presents as an lent or purulent ocular discharge (Figure accumulation of white blood cells (mainly 11). Treatment is with oral doxycycline at Toxoplasma gondii can present with plasma cells) in the anterior vitreous 10mg/kg once daily for three weeks (and systemic signs such as , fever, (termed ‘snow-banking’). Anisocoria with up to six weeks). Doxycycline can cause hepatitis, myositis, , diar- mydriasis, possibly related to CNS disease, reflux oesophagitis with resultant stricture rhoea and neurological dysfunction; and has been reported. FIV-positive cats formation, and therefore water or food with ocular signs such as anterior and/ or posterior uveitis. Cats with active have a higher rate of B-cell lymphoma, should follow tablet administration. It is ocular disease may have concurrent FIV which may occur in the uvea. FIV recommended to treat in-contact cats as infection. Diagnosis is made by serology, infection predisposes cats to opportunistic it is highly infectious, and also to prevent and treatment includes topical and oral infections such as Toxoplasma gondii, which the development of a latent carrier state steroids along with oral clindamycin may also cause uveitis. due to sequestration in the urogenital and gastrointestinal tracts. (25mg/kg every 12 hours for 21-30 days). Feline calicivirus (FCV) is a common Uveitis may become recurrent. cause of upper respiratory disease. Typical Figure 2: Herpetic keratitis in a five-month-old dom- Figure 6: FHV-1 associated periocular dermatitis Mycoplasma felis has been reported to estic shorthair with Rose Bengal positive dendritic bilaterally. Note the left dorsolateral cornea also Leishmania infection in cats is uncom- systemic signs of infection include fever, cause conjunctivitis, chemosis, follicle and Figure 10: Haws syndrome. Bilateral protrusion ulceration (pathognomonic for FHV-1 infection) has a corneal sequestrum mon, but has been reported in Portugal, , oral mucosal ulcerations and of the third eyelid in a cat with diarrhoea pseudomembrane formation, but it has Spain, Italy, France, Greece, Israel, Pales- chronic stomatitis. In the past it was also been isolated from clinically normal tine and Brazil. Ocular signs have been thought to be only associated with mild cats. Mycoplasma infection may be self- reported in one third of affected cats and conjunctivitis, but more recently it is limiting but could be treated with oral can include blepharitis, conjunctivitis and thought to cause more significant ocular doxycycline for 3-4 weeks. anterior uveitis progressing to panoph- surface disease, especially conjunctival thalmitis (Pennisi et al. 2015). Treatment Bartonella henselae is transmitted by ulceration. Laboratory diagnosis is made is with systemic pentavalent antimonials, fleas and causes cat scratch fever in people. by virus isolation or by PCR. FCV is such as allopurinol (10-20 mg/kg once or There is some debate about whether it an RNA virus, and therefore cannot twice daily) longterm. be effectively treated with antiviral can cause uveitis in cats, but it has been medications that inhibit DNA synthesis, isolated in some cases without being Fungal infections are not very common such as those used to treat FHV-1. the proven cause of disease (Stiles 2011). in cats in Europe, and are more common The use of topical broad spectrum Other ocular signs include blepharitis, in immunosuppressed individuals. Cryp- is always advisable to reduce Figure 3: Symblepharon in a two-year-old cat due to conjunctivitis, keratitis, and chorioretinitis. tococcus is the most commonly reported complications associated with secondary FHV-1 infection. There is adhesion of conjunctiva to Figure 7: FIP-associated uveitis in a young cat. Suggested treatment is with oral doxy- Figure 11: Conjunctivitis with chemosis and infection and it can cause chorioretinitis There are multiple haemorrhagic keratic precipitates, bacterial infection. Topical or systemic the corneal surface cycline for several weeks (6-12 weeks), conjunctival hyperaemia caused by Chlamydia with granulomatous inflammation, the peripheral iris is thickened and hyperaemic, and felis infection non-steroidal anti-inflammatory drugs there is miosis and ectropion uveae in combination with an oral fluoroqui- anterior uveitis, retinal detachment and (NSAIDs) could be considered when nolone. Azithromycin has been used, but optic neuritis. Aspergillosis, blastomycosis, inflammation is severe or prolonged. the organism can become resistant to it. histoplasmosis and coccidiomycosis can cause similar chorioretinal lesions. Cytol- Tora-like virus has been implicated in Mycobacteria species infections can ogy or histopathology samples are used to causing ‘Haws’ syndrome. In this condi- cause several different ocular signs. These diagnose the mycoses. Antifungal therapy tion, bilateral nictitans protrusion occurs, include blepharitis, conjunctivitis, keratitis can be achieved with systemic ampho- and there may also be symptoms of and uveitis (Figure 12). Systemic signs tericin B, ketoconazole, fluconazole or diarrhoea or (Figure 10). may include bronchopneumonia, pulmo- itraconazole, which are fungistatic rather It is thought to occur due to a reduction nary nodules, fever and cough. Diagnosis than fungicidal. in sympathetic tone. It is self-limiting but can be made from cytological aspirates may continue for several weeks. and impression smears with acid-fast stain. Parasitic infections Feline panleucopenia infection in utero Figure 4: Proliferative (eosinophilic) keratitis due A tissue sample should be divided in four: Feline demodecosis is an uncommon can result in retinal dysplasia and optic to FHV-1 infection. There is a thick white plaque Figure 8: FeLV-associated lymphoma and uveitis. one sample preserved in formalin for systemic skin condition that may be on the lateral conjunctiva, lying on a densely The right eye has corneal ulceration, oedema histopathology, one quarter left unfixed caused by infection with Demodex cati nerve hypoplasia. Affected kittens may also neovascularised cornea. Note the single distichium and neovascularisation. The left eye has cornea Figure 12: Mycobacterial blepharitis with thickened for bacterial culture and two frozen have cerebellar hypoplasia and generalised (cilium arising from a meibomian gland orifice; cellular infiltrate, miosis and posterior synechiae and protruding third eyelid and a skin nodule on the or Demodex gatoi. Localised periocular immuno-suppression. arrowed) in the upper eyelid unfixed samples which could be sent for upper eyelid demodecosis can occur and is usually

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