A challenging case: Blindness and a history of cutaneous nodules in a cat

Ocular signs, a decreased appetite, and previous skin nodules were the only clues that this indoor-only cat had a life-threatening disease.

A 12-year-old 8-lb (3.6-kg) castrated male domestic shorthaired cat was evaluated initially at Bissonnet/Southampton Veterinary Clinic followed by evaluation at Gulf Coast Animal Eye Clinic and Gulf Coast Veterinary Specialists for blindness of one monthduration. The owner had observed the cat walking along the perimeter of rooms and showing a reluctance to jump up on things. The cat's activity level had decreased as well. The cat's appetite was normal initially but began to decrease over the subsequent weeks. The owner had not noticed any coughing, sneezing, nasal discharge, vomiting, or abnormal stools.


Vital Stats
The cat was indoor-only; another cat in the household was indoor-outdoor. About a month before presentation, the cat was vaccinated by its previous veterinarian against rabies, feline rhinotracheitis, feline panleukopenia, and calicivirus, feline leukemia virus (FeLV), and feline immunodeficiency virus (FIV) infections.

HISTORY

Five months before this presentation, another veterinarian had evaluated the cat for recurrent ulcerated nodules on its head. A biopsy and histologic examination of the initial lesions had revealed chronic nodular pyogranulomatous dermatitis and panniculitis. No infectious agents had been identified. The lesions resolved after treatment with penicillin and dexamethasone followed by enrofloxacin. However, the lesions reappeared about two months later and were treated with the same regimen. The lesions appeared to resolve a second time.

PHYSICAL AND OPHTHALMIC EXAMINATIONS

At presentation, physical examination findings were unremarkable except for a few small excoriations rostral to the right ear. The owner had not noted pruritus, so the excoriations were attributed to trauma, possibly from the other cat in the household.

An ophthalmic examination revealed changes consistent with granulomatous chorioretinitis and pan uveitis in both eyes. Other ophthalmic findings included bilateral conjunctival hyperemia, moderate corneal stromal edema, keratic precipitates (left eye), bilateral moderate aqueous flare and cells, dilated and fixed pupils, nuclear sclerosis, marked vitreous cellular infiltrates and fibrin clumps, bilateral exudative detachment affecting the inferior portion of the retinas, and numerous intraretinal and subretinal granulomas. Intraocular pressures were normal at 14 mm Hg, and iridocorneal angles exhibited moderate narrowing. Dazzle light reflexes were present in both eyes but were markedly reduced.

DIAGNOSTIC TESTING

Abnormalities detected on a complete blood count and serum chemistry profile included anemia (packed cell volume 24%; reference range = 29% to 48%), eosinophilia (absolute eosino phils 1,365 units/μl; reference range = 0 to 1,000 units/μl), hyperglobulinemia (7.1 g/dl; reference range = 2.3 to 5.3 g/dl), mildly elevated blood urea nitrogen (BUN) concentration (38 mg/dl; reference range = 14 to 36 mg/dl), mildly elevated amylase activity (1,225 IU/L; reference range = 100 to 1,200 IU/L), and elevated creatinine kinase activity (1,553 IU/L; reference range = 56 to 529 IU/L). Urinalysis revealed a low urine specific gravity (1.023). Urine bacterial culture results were negative. Tests to detect FeLV and FIV infection were recommended after the blood test results were evaluated, but attempts to contact the owner to obtain permission failed.

DIFFERENTIAL DIAGNOSES

Differential diagnoses for the anemia include anemia of chronic renal disease, anemia secondary to inflammation or infection, FeLV infection, FIV infection, bone marrow disorders, and neoplasia. Differential diagnoses for the eosinophilia include allergic disease, parasitic diseases, neoplasia, fungal infection, and viral infection such as FeLV infection. Differential diagnoses for the hyperglobulinemia include infectious disease and neoplasia. Differential diagnoses for the elevated BUN concentration with concurrent low urine specific gravity include chronic or acute renal insufficiency and pyelonephritis. The elevated amylase activity was attributed to renal insufficiency. Differential diagnoses for the mild creatinine kinase activity elevation include restraint, physical activity, and trauma. The increase was considered too small to be attributed to a primary myositis. Differential diagnoses for the ocular lesions include ocular mycoses and mycobacterial infection.