This study evaluated the side effects of immunosuppressive doses of dexamethasone and prednisolone in 14 intact male cats. Cats were divided into 2 groups. One group received 4.4 mg/kg/day of dexamethasone, and the other received 0.55 mg/kg/day of prednisolone. Drugs were each administered once daily for 56 days. Complete blood count (CBC), serum biochemistry, and urinalysis were performed in each cat at day 0 and at day 56. Sampling was performed in a manner to minimize the effects of clinical stress on the results. Abdominal ultrasonography was conducted in 3 cats with high alanine aminotransferase (ALT) levels, but no ultrasonographic abnormalities were identified. Liver biopsies were taken at the end of the study. Pancreatic biopsies were taken at the beginning and end of the study because this was part of a primary diabetogenesis study. All diagnostic and clinical changes were compared at day 0 and at day 56 to elucidate statistically significant differences. All cats had polyuria and polydipsia. One cat treated with dexamethasone developed clinical illness with anorexia, icterus, left thigh erosions, and medial pinnal curling (a rare complication of glucocorticoid treatment). Glucosuria was significantly increased after dexamethasone treatment. Vacuolar hepatic changes consistent with steroid hepatopathy were present in all liver biopsy samples. Changes in the CBC were consistent with steroid responses. In conclusion, all cats had steroid hepatopathy changes, and administration of dexamethasone had a more potent effect than prednisone on lipid and glucose metabolism in this experimental cat sample.

COMMENTARY: The clinical veterinarian will find this study helpful in understanding the unique changes secondary to steroid treatment in cats. Specific clinical and biochemical side effects were identified in this analysis that hint at the potential of greater steroid side effects with dexamethasone therapy. It is also notable that experimental clinical results seen in this feline sample were distinct from some clinical changes seen in dogs in other evaluations. The sample size in this study was small, and further studies with greater statistical power may allow stronger conclusions about steroid side effects and evaluation of the effects of these drugs on other body systems.

Clinical, clinicopathological and histological changes observed in 14 cats treated with glucocorticoids. Lowe AD, Campbell KL, Barger A, et al. VET REC 162:777-783, 2008.