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Objective—To determine responses of canine and feline lenses to incubation in a medium with a high glucose concentration.

Sample Population—Lenses from 35 dogs and 26 cats.

Procedure—Glucose concentrations were measured in paired lenses from 25 dogs and 17 cats after incubation for 14 days in high-glucose (30 mmol of glucose/ L) or control (6 mmol of glucose/L) medium. Aldose reductase activity was measured spectrophotometrically in the incubated lenses and in freshly frozen lenses from 10 dogs and 9 cats. Two lenses of each group were studied histologically.

Results—Canine and feline lenses in high-glucose medium developed glucose-specific opacities of variable localization and extent. Canine lenses developed equatorial vacuoles, but severity of the lesions was not associated with the age of the dog. Lenses from young cats (≤ 4 years old) developed extensive posterior cortical opacities, whereas those from older cats (> 4 years old) did not. Glucose concentrations were similar in all lenses incubated in high-glucose medium; however aldose reductase activity was significantly lower in lenses from older cats, compared with lenses from young cats and from dogs.

Conclusions and Clinical Relevance—High aldose reductase activity and glucose-related opacities suggest a central role for this enzyme in the pathogenesis of diabetic cataracts in dogs and cats. Because onset of diabetes mellitus usually occurs in cats > 7 years of age, low activity of aldose reductase in lenses of older cats may explain why diabetic cataracts are rare in this species despite hyperglycemia. (Am J Vet Res 2002;63:1591–1597)

Full access
in American Journal of Veterinary Research


Objective—To assess the biological response to recombinant feline interferon-omega (rFeIFN-ω) following ocular or oral administration in cats via estimation of Mx protein expression in conjunctival cells (CCs) and WBCs.

Animals—10 specific pathogen–free cats.

Procedures—In multiple single-dose drug experiments, each cat received various concentrations of rFeIFN-ω administered topically into both eyes (50 to 10,000 U/eye) and orally (200 to 20,000 units). The same cats received saline (0.9% NaCl) solution topically and orally as control treatments. The CCs and WBCs were collected prior to treatment (day 0), on day 1, and every third or seventh day thereafter until samples yielded negative results for Mx protein. Samples were examined for Mx protein expression via immunohistochemistry and immunoblotting procedures involving murine anti-Mx protein monoclonal antibody M143.

Results—After topical application of 10,000 U of rFeIFN-ω/eye, CCs stained for Mx protein for a minimum of 7 days, whereas WBCs were positive for Mx protein for a minimum of 31 days. After topical application of lower concentrations, CCs did not express Mx protein, in contrast to WBCs, which stained for Mx protein at 1,000 units for at least 1 day. Following oral administration, Mx protein was expressed in WBCs at rFeIFN-ω concentrations as low as 200 units, whereas CCs did not stain for Mx protein at any concentration.

Conclusions and Clinical Relevance—Results indicate that Mx protein expression (a marker of the biological response to rFeIFN-ω) in CCs and WBCs of rFeIFN-ω–treated cats depends on the dose of rFeIFN-ω, site of administration, and cell type.

Full access
in American Journal of Veterinary Research