I second Michelle's message about no steroids for a kitty with heart problems. My cat Aja was given a steroid injection for stomatitis (mouth inflammation). Two days later she was in ICU for the weekend. I didn't know she had HCM, and the steroid injection caused pulmonary edema. That means her lungs were filling with fluid and she couldn't breathe. Aja's story has a happy ending because she survived. After she recovered from the pulmonary edema she had I131 for hyperthyroid, and her heart problem resolved when hyperthyroid was cured.