My cat was diagnosed with hyperthyroidism in May.

When we started medicating him, he got 1/2 5mg tab of Methimazole 2 time a day. After 2 weeks, dose increased to 2 tabs 2 times a day. He had gone from 14-9 pounds -has regained 1 1/2 pounds. He also has a heart murmer. His energy & muscle increased. His breathing went from 60 breaths/min -to normal-about 38. In the last week or so, his breath rate has again increased to about 48-50 breaths/min. His energy level has decreased again. He doesn't seem in pain. Your help is greatly appreciated.

  • Vetinfo

    By: Erika Raines El Segundo, CA

    Replied on 04/19/2011

    Your cat is likely suffering further from his hyperthyroidism. Levels of thyroid hormone can change over time which necessitates regular monitoring of the levels of thyroid hormone and possible alterations in the dose of Methimazole. It sounds like you should visit your veterinarian again and have your cat's thyroid hormone levels re-measured. The other possibility is that your cat is now suffering from the effects of kidney failure. Hyperthyroidism can mask the signs and abnormal blood chemistry parameters that occur in kidney failure and both of these will reappear when the hyperthyroidism is treated with Methimazole. You should have your veterinarian run blood tests to make sure that your cat's kidneys are functioning normally as well as to recheck the levels of thyroid hormone. Erika, DVM

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