Uveitis - Cat and Dog

Introduction

Uveitis refers to inflammation of the uvea.

Various parts of the uvea, aqueous humour and vitreous are continuous, and uveitis often involves many ocular structures.

The retina and choroid are adjacent and are frequently inflamed together.

Anterior uveitis referes to inflammation of the iris and ciliary body whereas posterior uveitis refers to inflammation of the choroid.

The pathogenesis of uveitis is still poorly understood, but immunologic reactions are involved. There are alterations in the vascular structure and permeability of uveal blood vessels following inflammation, and immune complexes can be deposited in vessels and lead to a chronic and recurrent disease.

Causes

Cats

Infectious causes:

Feline Infectious Peritonitis

FeLV causing lymphosarcoma

FIV

Feline Herpesvirus 1

Toxoplasmosis

Bartonella spp

Systemic mycoses (cryptococcosis, histoplasmosis, blastomycosis, coccidiomycosis)

Neoplasia: Lymphoma, melanoma

Metabolic causes: hypertension, coagulopathies

Immune-mediated: cataract, phagoclastic uveitis, vasculitis

Trauma: blunt or penetrating injuries, corneal foreign bodies

Idiopathic

Dogs

Infectious causes:

Brucella canis

Borrelia burgdorferi

Leptospira

Septicaemia of any cause

Leishmania

Toxoplasma

Erlichia canis

Rickettsia rickettsii

Adenovirus infection

Distemper virus

Herpes virus

Rabies

Systemic mycoses (cryptococcosis, histoplasmosis, blastomycosis..)

Neoplastic and paraneoplastic disorders: histiocytic proliferative disease, hyperviscosity syndrome, GME, primary (melanoma) and secondary (lymphoma) neoplasms.

Metabolic causes: Diabetes mellitus, hyperlipidaemia, systemic hypertension

Immune-mediated: cataracts, immune-mediated thrombocytopenia, immune-mediated vasculitis, phacoclastic uveitis, uveodermatologic syndrome

Miscellaneous: drug-induced, idiopathic, pigmentary uveitis in the Golden Retriever, radiation therapy, trauma, toxaemia of any cause, ulcerative keratitis.

Clinical Signs

Animals will usually present because the owner has noticed a change in one or both eyes. There is usually a colour change, cloudy or red most commonly.

The condition may be unilateral or bilateral. Bilateral disease is more common with systemic and auto-immune diseases, whereas trauma usually lead to unilateral signs.

Acute uveitis causes: pain, ciliary flush, miosis, aqueous flare, spongy swollen iris, corneal oedema, decreased intra-ocular pressure

Hyphaema may be present and make the eye appear red.

A combination of aqueous flare, hypopyon, keratic precipitates and cataract will make the eye appear cloudy.

A fundus examination may reveal chorioretinitis and retinal detachment.

With chronic uveitis, additional signs may include: neovascularisation of the iris, changes in iris pigmentation, secondary iris atrophy, synechiae, cataract, glaucoma, lens luxation and blindness.

Diagnosis

A thorough clinical examination and ophthalmic examination should enable a diagnosis of uveitis to be made.

Further investigation into the cause of the uveitis should include:

Complete haematology and biochemistry

Urinalysis

Thoracic radiography

Serological testing for Toxoplasma, FeLV, FIV

Additional diagnostic tests are selected according to diseases that are endemic to a particular practice area or on suspicion of a particular disease.

Often, a precice aetiological diagnosis is not possible, and idiopathic uveitis is a diagnosis of exclusion.

Treatment

Treatment should be targeted at the specific cause if one has been found.

Additional treatment can be given to:

Control inflammation: topical or systemic corticosteroids, topical or systemic NSAIDs, topical immunosuppressive drugs such as cyclosporin.

Prevent undesirable sequelae: mydriatics to reduce synechiae formation and secondary glaucoma (atropine or tropicamide), anti-glaucoma agents if necessary

Relieve pain: atropine helps reduce ciliary spasm. The patient can also be placed in a dark room to alleviate photophobia. A systemic opioid analgesia may be necessary in severe cases.

Uveitis - Cat and Dog Learning Resources
Flashcards Test your knowledge using flashcard type questions	Feline Medicine Q&A 16 Small Animal Emergency and Critical Care Medicine Q&A 14

References

Maggs, D. (2008) Slatter's fundamentals of veterinary ophthalmology Elsevier Health Sciences

Turner, S. (2008) Small animal ophthalmology Elsevier Health Sciences

Peiffer, R. (2008) Small animal ophthalmology: a problem-oriented approach Saunders