My cat's thyroid is high on methimazole. What symptoms to watch for?

Hi there. Hyperthyroidism can cause symptoms like increased vocalization and irritability, weight loss, increased appetite, vomiting or diarrhea, and/or increased drinking and urination. It also contributes to high blood pressure, and is hard on the heart and kidneys long-term. If Midnite's thyroid levels are high, treatment would generally be recommended to address this.

I am sorry to hear that you and Ricochet are having a hard time. Unfortunately, the only way to see if the dose needs to be increased is to do bloodwork to evaluate his thyroid level. It is important to remember that there are other possible causes for him to be yowling at night, besides hyperthyroidism, including behavioral causes, cognitive dysfunction and potentially other metabolic causes and that increasing his methimazole too much will be harmful to Ricochet. I would recommend continuing the dose as prescribed by your vet and talking to them about what can be done to get Ricochet in for a blood test. Some clinics will accept payment plans or work with you to make sure that Ricochet gets the care he needs without putting you guys out of house and home. Again, so sorry you and Ricochet are going through this - you clearly care a lot about him and I hope he feels better soon! Also, to answer your question, the signs you may notice will be resolution of his signs of hyperthyroidism (typically, hyperthyroid cats exhibit weight loss despite voracious appetite, increased thirst, increased urination, among other possible signs). Hyperthyroidism can also affect other organs in the body like the kidneys, heart, brain and eyes, so sometimes we can see secondary disease in these organs with hyperthyroidism.

These signs could be consistent with methimazole related side effects. GI upset and facial itching are some of the most common acute side effects in the first few months of therapy. I would recommend stopping the medication until you can talk to your vet about your concerns. Some cats can not take this medication and thus require an alternate method of treatment. If still eating and drinking that is good. If any of the symptoms worsen an ER visit is advised. I hope this helps and thank you for using Petco Pet Education Center, formerly Petcoach!

Luv Bug is so very fortunate to have you as an owner. I am sure that you are one of the main reasons that she is going strong at 17 years of age. Kudos to you for your consideration and compassion for your pet. In terms of hyperthyroidism in cats, there are only three real treatments on the market today. These are methimazole treatment, thyroidectomy surgery, and radioactive iodine treatment. It is believed in the veterinary community that radioactive iodine is the gold standard treatment today. With the information you have provided, I can offer you a few possibilities for future treatment: 1. Perhaps you can get the math him is all in a tablet form to crush it into a fine powder and then mix it with any palatable substance that she likes and then squirt it in her mouth with a syringe. This, however, may cause some behavior problems because she may not like this either. 2. If you are willing to accept the costs and all of the different parts that go with the radioactive iodine treatment, I say go for it because the success rate for that specific treatment is excellent. Thank you very much for your question and I know you will make the right decision on her behalf. Have a great day.

Yes I would stop the methimazole until you can have him checked again by your veterinarian. If he feels better off the methimazole then the methimazole dose may have been too high. They will check his blood work again for the thyroid level and for the pancreatitis. When changing diets I try adding just a small amount of new food at each meal until he gets used to it. Cats are fussy eaters but if he's still not eating it may be that Jojo just doesn't feel well and it wasn't that he didn't like the food. Once cats get regulated on the thyroid medication usually things smooth out and you'll have less problems. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Jojo.

I am sorry to hear about Midnite. I would call and let your vet know of the symptoms. You don't mention if he just started this medication or if he has been on it long term. Some cats can experience lethargy and GI upset when first starting the medication and in some cases we need to start at a lower dose and taper it up, but you need to consult with your vet in order to know if this is the right course of action for your kitty. If he has been on methimazole for a long time and just started with the lethargy/decreased appetite, then an exam and possibly bloodwork are in order for him to ensure there isn't another cause for his symptoms.

Cats rarely develop HYPOthyroidism (low thyroid values), but instead typically develop HYPERthyroidism (elevated thyroid values). I assume that with a thyroid (T4) value of 13 (which is very high!), Mama is being treated for hyperthyroidism. Methimazole is a medication that works to suppress, or lower, thyroid hormone. Since she is not responding to her current dose of medication, your vet increased her methimazole dose to try to bring her T4 value back to a normal range.