|
Definition
Posterior uveitis involves the choroid and cannot be clinically distinguished from retinitis. It is therefore usually described as chorioretinitis. EtiologyChorioretinitis in the cats is frequenly caused toxoplasmosis, Feline infectious peritonitis (FIP) , cryptococcosis, Histoplasmosis and Blastomycosis. Toxoplasmosis and cryptococcosis commonly involve only the posterior segment, although anterior and posterior uveitis may occur. Chorioretinitis in dog is caused by caused by bacterial, viral and fungal infections, parasites and primary and secondary neoplasia.
Pathophysiology- Caused by infectious agents, neoplastic or immune cells, or immune complexes (immune-mediated diseases); hematogenous pathogenic factors, inducing choroidal inflammation, most common
- Choroid and retina-closely apposed; physiologically interdependent; inflammation of one usually results in inflammation of the other.
- May also occur as a retinochoroiditis-retinal inflammation preceding and inducing choroidal inflammation
Clinical presentation/signs
The signs of retinal or chorioretinal inflamation include edema, infiltration with inflammatory cells and granuloma formation, hemorrhage and possible exudative detachment. In dogs retinal exudates, hemorrhage and retinal detachment are sequelae.
Lesions- Indistinct margins; tapetal hyporeflectivity; white-gray color
- Alter course of retinal blood vessels
- Few, small may note no apparent visual deficits
- Extensive, involving larger areas of the retina blindness or reduced vision
- Inactive (scars) discrete margins; hyperreflective in the tapetum sometimes with hyperpigmented central areas; depigmented in the nontapetum and may have some surrounding or central hyperpigmentation
Diagnosis
Chorioretinal scars, characterized by hyperreflective areas in the tapetal region, are observed in normal healthy cats and are an indication of a previous subclinical inflammatory process
Differential Diagnosis - Ophthalmic examination, usually sufficient for diagnosis; may note a slow pupillary light reflex if large areas of the retina are affected
- Blindness or impaired vision, optic neuritis; CNS disease; diffuse retinal inflammation
- See Causes
- Retinal dysplasia, similar to inactive disease; bilateral, symmetrical folds or geographic clumps of pigment or altered fungus reflectivity; no associated signs inflammation in the eye; Labrador retrievers and springer spaniels predisposed
Treatment- Identify and definitely treat any underlying systemic disease (e.g., itraconazole for systemic mycosis).
- Systemic therapy required
- Systemic prednisone at anti-inflammatory doses 0.5 mg/kg PO, then taper; when systemic mycosis has been ruled out or is being treated with appropriate systemic antifungal therapy; avoid use, unless large areas of the retina are affected and vision is severely threatened.
- Prednisone at immunosuppressive doses 2mg/kg divided q12 for 3-10 days (ideal), then taper very slowly over months; for immune-mediated disease; may facilitate retinal reattachment
- Topical corticosteroids (1% prednisolone acetate or 0.1% dexamethasone give TID to QID) and parasympatholytics (1% atropine given at a frequency that dilates the pupil and reduces pain) for panuveitis (concurrent anterior uveitis)
- Anti-glaucoma therapy as appropriate for secondary glaucoma.
Tags: Article Pets Animals Chorioretinitis
|
Category Article 
