Topical Methimazole for Cats

Methimazole, also known by the brand name Tapazole, is a medication used to treat hyperthyroidism. Methimazole is available in pill form and as a lotion or gel that is applied to the inner part of your cat's ear. Most times topical application is easier than trying to pry open your cat's mouth and shove a pill down her throat, but there's always a price for convenience: VetInfo reports that the topical form of methimazole is more expensive than the pills.

Hyperthyroidism is a fairly common condition that can affect older cats, regardless of their gender. An article on the website Healthy Pet reveals that the condition causes elevated levels of thyroid hormones that speed up your cat's metabolism and can lead to other complications such as high blood pressure, kidney or intestinal problems and enlargement of the heart. If you notice any symptoms of hyperthyroidism in your older cat, such as weight loss, increased appetite, vomiting, hair loss or increased thirst and urination, make an appointment with her vet immediately. He should be able to diagnose the condition through a physical exam and standard blood tests and can discuss prescribing methimazole for your cat.

Methimazole is typically an ideal choice for treating hyperthyroidism in cats because of the low occurrence of side effects. As with any medication, however, side effects can occur and usually do so within the first three months of treatment. If your cat has been prescribed topical methimazole to treat her hyperthyroidism, be on the lookout for loss of appetite, vomiting and depression. The appetite and digestive issues are typically related to taking the drug orally, so they're unlikely. If your cat becomes depressed your vet may have to adjust her topical dosage. If your cat is on methimazole for six months or longer, odds are she will develop an autoimmune disease, making routine visits with her doctor while using methimazole vital to her health. Other, more rare side effects include excessive scratching, bleeding and the development of blood disorders.

If your cat develops hyperthyroid disease, she will be on methimazole for the long term, provided she doesn't develop any of the serious side effects associated with the drug. According to VetInfo, if side effects occur and are severe, your vet will discontinue methimazole and replace it with an alternate treatment. Radiation therapy is an alternative that you can opt for, especially if you don't want your kitty on medication for life. Treatment with radiation requires that your cat's hormone levels be normal, though, so you may have to wait to schedule it. The good news is that only one dose of radiation is necessary and will usually cure hyperthyroidism in cats.