Feline opthamology Flashcards
What is chlamydiophila felis?
An obligate intracellular bacterium, primarily causes conjunctivitis without respiratory infection. It does not cause corneal ulceration. Diagnosis in the acute stage is confirmed by identifying intracytoplasmic inclusion bodies in epithelial cells from conjunctival scarpings. Systemic treatment with doxycyline is most effective.
What problems occur in the nictitating membrane in cats?
Bilateral prominence of the third eyelid is a common sign in the cat, frequently observed in association with systemic disease, particularly diarrhoea. Unilateral prominence may be a sign of ocular surface pain, retrobulbar swellings, horners syndrome or symblepharon.
What is feline herpes?
FHV is a freequent cause of conjunctivitis and ulceration and not necessarily both together. Less frequently it presents as stromal keratitis. The signs are generally related to the age o the animal at presentation - neonatal infection - opthalmia neonatorum, young cats - cat flu with conjunctivitis and sometimes corneal ulceration, older cats - recrudescence of latent infection causing refractory ulcers, stromal keratitis or chronic conjunctivitis. Corneal sequestrum formation and KCS appear commonly in this group. Dendritic ulcers are pathognomic for feline herpes virus.
What is the treatment of Feline herpes virus?
General nursing care, cleaning the eye, broad spectrum antibiotics. Antiviral agents effective in acute cases. Reactivation of a latent infection following stress may result in a chronic conjunctivitis and or superficial ulceration that is usually self limiting but uncomfortable and takes weeks to resolve. Supplementation of the diet with L lysine may be useful.
What is symblepharon?
Feline conjunctival surfaces tend to form adhesions when inflamed and these may involve the palpebral and bulbar conjnctiva, the nictitating membrane and the cornea in various combinations. It is particularly associated with FHV infection in young cats. Sometimes the corneal epithelium is replaced by a conjunctiva like membrane following extensive ulceration.
What is corneal sequestrum?
A black plaque extruding through the corneal epithelium is the most usual presentation. Best treated by keratectomy. A conjunctival pedicle graft may be useful in preventing recurrence. sometimes there is no obvious discomfort, the lesion appearing as a tan coloured discolouration.
What is eosinophilic keratitis?
Proliferative superficial keratitis of unknown aetiology (infiltrates of lymphocytes, eosinophils and plasmocytes), which typically has a cottage cheese appearance on the cornea near the medial or lateral limbus, frequently involving the adjacent conjunctiva. Non ulcerative, mild signs of discomfort, may look like a tumour.
What is anterior uveitis associated with in the cat?
FIV, FelV, FIP - pyogranulomatous uveitis, Toxoplasmosis - posterior segment disease - graulomatous chorioretinitis. Idiopathic - low grade chronic uveitis in older cats, frequently unilateral.
What is the most common uveal neoplasia in the cat?
Melanomas. Most arise from the iris and these sometimes cause a patchy increase in pigmentation, difficult to distinguish from benign changes - enucleate if causing secondary glaucoma or if there is obvious iris thickening. Lymphoma also occurs within the eye. Primary intraocular sarcomas may occasionally appear years after trauma - malignant.
Describe glaucoma in the cat
The onset of clinical signs in cats is often insidious, they may only show mydriasis with less episcleral congestion or overt discomfort than the dog. Most glaucoma in the cat is secondary to obstruction of the drainage angle from a chronic or acute uveitis. Recently one study showed aqueous misdirection syndrome to be a significant cause. Prostaglandin analogues do not lower IOP in this species. Normal IOP is 20.20 in the cat. Readings over 32mmhg are significantly elevated.
Describe the feline fundus?
There is much less variation in the normal feline fundus compared to the dog. The tapetum is very bright, most frequently a yellow/green colour. The disc is usually found 1-2 disc diameters into the tapetum, it is round, dark grey-pink and the vessels do not anastomose on the disc surface. The ganglion cell axons myelinate at the level of the lamina cribrosa in the cat, not around the disc as in the dog. The fundus immediately adjacent to the disc frequently shows conus and pigmentation.
What is taurine deficiency retinopathy?
Causes retinal degeneration and dilated cariomyopathy in the cat. Very rare now. Dog food does not contain adequate levels of taurine for cats. The retinal degeneration initially appears as a bilaterally symmetrical hyperreflective band in the area centralis which extends medially over time, until total diffuse retinal degeneration occurs. Ocassionally seen in cats fed a diet containing adequate taurine, which may reflect individual absorption problems.
What is generalised retinal atrophy?
A generalised retain atrophy progressively slowly to complete blindness, recognised in abysinnian and siamese. Mixed breed cats are also affected and are often presented very late in the disease as they cope so well with profound visual impairment.
What is hypertensive retinopathy?
Any cat exhibiting sudden onset visual loss should have BP measured. Opthalmoscopic findings include retinal and vitreal haemorrhage, retinal detachment and tortuosity of the retinal areterioles with variation in arteriolar calibre. Hyphaema may also occur and IOP should be monitored until this has cleared.
What is feline panleucopaenia virus?
Antenatal or neonatal infection with the virus can cause retinal dysplasia with/without cerebellar hypoplasia. Cerebellar function is necessary for the menace response - kittens with cerebellar hypoplasia may lack a menace response despite being visual.
