Some effects of short-term methylprednisolone therapy in normal cats

Four normal cats were treated weekly for 4 weeks with repositol methylprednisolone. Hemograms, serum chemistry panels, urinalyses, 24 hour water consumption, physical and constitutional parameters, and blood cortisol responses to ACTH stimulation were monitored before and during a day were done prior to steroid therapy on each cat. Clinicopathologic abnormalities induced by steroid therapy were, on the whole, inconsistent and minor. The most important findings were: (1) marked steroid-induced suppression of blood cortisol responses to ACTH, and (2) a circadian rhythm of blood cortisol production that was opposite to that of humans and dogs.