Corticosteroids, particularly methylprednisolone acetate (MPA, Depo-medrolâ), are commonly used to treat a variety of inflammatory conditions in cats. At the University of Minnesota we have observed an association in cats between development of heart failure and a history of recently receiving corticosteroids. This rare side effect was observed most commonly in cats that had received MPA. Heart failure may occur when the blood stream is water overloaded. MPA is generally thought to not cause significant water retention in cats, but we suspect that the development of heart failure in these cats is due to a previously undocumented water retention problem that occurs as a side effect of MPA. To better characterize the impact of this drug on body water status, we plan to evaluate body water levels in cats before and after they receive MPA as treatment for inflammatory conditions primarily of the skin. We will also determine if there are any effects on heart function. We hope to use this information to better predict which cat may develop heart failure as a side effect of corticosteroids, and to better treat those that do.