Although cats appear to not experience as many side effects with glucocorticoids as other species do, adverse reactions can occur, including skin atrophy and fragility, poor wound healing, and a predisposition to diabetes mellitus and congestive heart failure.
Glucocorticoids are some of the most common drugs prescribed in practice because they have a variety of therapeutic effects. Although cats appear to not experience as many side effects with glucocorticoids as other species do, adverse reactions can occur, including skin atrophy and fragility, poor wound healing, and a predisposition to diabetes mellitus and congestive heart failure. Cats do not seem to develop steroid hepatopathy as dogs do, but this condition may just occur less frequently or be more difficult to detect in cats. A recent article in Veterinary Dermatology reviews what is known about glucocorticoids in cats, explaining how glucocorticoids produce their therapeutic effects and what processes are thought to result in the side effects mentioned above.
Overall, the metabolically active drug prednisolone seems to be the preferred glucocorticoid in cats (anti-inflammatory dose 0.55 to 1.1 mg/kg/day divided once or twice a day; immunosuppressive dose 2.2. to 8.8 mg/kg/day divided once or twice a day). Many authors recommend that cats be given doses twice that of dogs to achieve anti-inflammatory effects. Contrary to previous study findings, subsequent larger studies have documented episodic cortisol secretion with no circadian rhythm, so the time of day is probably not important in glucocorticoid dosing in cats. Using short- to intermediate-acting glucocorticoids is recommended to monitor for adverse effects and quickly discontinue the drug if any adverse effects occur. Repositol glucocorticoids should be reserved for cats in which oral dosing is not possible. At therapeutic doses, cats receiving glucocorticoids should be able to produce normal antibody responses to antigens, including vaccines. Because of glucocorticoid's association with diabetes mellitus and congestive heart failure, careful administration is warranted in cats at risk for diabetes or with preexisting heart disease.
Lowe AD, Campbell KL, Graves T. Glucocorticoids in the cat. Vet Dermatol 2008;19(6):340-347.