A challenging case: An unusual cause of blindness in a Siberian husky

Despite a lack of other obvious physical abnormalities or signs, systemic disease was suspected of causing this dog's eye problems.
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Mar 01, 2007


Vital Stats
A 12-year-old 57-lb (26-kg) castrated male Siberian husky was presented to the Colorado State University Veterinary Teaching Hospital for evaluation of blindness of three weeks' duration, depression, and polydipsia.

PERTINENT HISTORY

The dog had undergone a laparotomy at Rowley Memorial Animal Hospital in Springfield, Mass., five months before presentation. During the surgery, an adrenal and a liver mass were excised. Histologic examination revealed that the masses were an adrenocortical adenoma and a well-differentiated hepatocellular carcinoma and that hepatocellular swelling with lymphohistiocytic and eosinophilic inflammation was present. The prognosis for the liver mass was considered good because hepatocellular carcinomas rarely metastasize and the histology report stated that complete removal is often curative. At that time, there was no serologic evidence of hyperadrenocorticism, thus the adrenocortical adenoma was considered nonfunctional.

The dog had recovered well from the surgery, but three months later had been presented to Rowley Memorial Animal Hospital because of a cloudy right eye. Uveitis was diagnosed, and diagnostic tests were done to attempt to identify the underlying cause. The results of a CBC, serum chemistry profile, and urinalysis were normal. An abdominal ultrasonographic examination revealed a mass where the adrenal tumor had been removed, which was thought to be either a recurrence of the tumor or a suture reaction. A thoracic radiographic examination revealed a mild bronchointerstitial pattern in the caudal dorsal lung field that was suggestive of thickening of the lungs due to an infection or an infiltrative neoplasia but was not considered consistent with metastasis. The dog was sent home with prednisolone acetate 1% topical eye drops to be administered three times a day and deracoxib (2 mg/kg) to be given once a day for five days.

Several weeks later, the owner had moved to Colorado. After the move, the dog became blind and was presented to a veterinarian who started treatment with oral prednisolone (5 mg every day) and continued the topical prednisolone drops. The dog was referred to the Colorado State University Veterinary Teaching Hospital for further evaluation.

INITIAL DIAGNOSTIC TESTS


Figure 1
On presentation, the dog was alert and active, although it bumped into things in the examination room. The dog's temperature, pulse, and respiratory rate were normal, as were findings of the remainder of the physical examination.


Figure 2
An ocular examination revealed a severe, bilateral panuveitis. Aqueous flare (2+ on a scale of 1 to 4) was observed in both eyes. The right eye had 360-degree posterior synechiae and iris bombé. In addition, there was a dense, immature cataract that precluded fundic examination. The left lens had dense nuclear sclerosis through which a massive retinal detachment and retinal hemorrhages could be discerned (Figures 1 & 2). The intraocular pressures measured by applanation tonometry (TonoPen Vet—Medtronic) were low in both eyes (5 mm Hg in the right eye and 6 mm Hg in the left eye; normal = 10 to 20 mm Hg) despite the posterior synechiae in the right eye. Since bilateral panuveitis is often indicative of a serious systemic disease, a complete diagnostic workup was recommended.