Original Question: "My cat has an overactive thyroid, which is why he bothers us at night. He started taking Tapazole (1.25mg 2x a day). It worked so well that after a month the level of hormones dropped so now he only gets 1.25 mg once per day. Our vet suggested we have his blood checked in 3 months. He would not like my cat to take this dose for too long since the meds have been working but our cat still wakes us at 4:40-5:00am.This is the lowest dose that can be given to a cat. Why he is so active that early when his hormone level is low? I can assure you that he is not hungry (gets dry food at night). I appreciate your reply." - Alicja
Thanks for your question.
Thyroid disease in cats is very common. Basically the thyroid hormone controls their metabolism and many cats can develop an overactive thyroid gland which produces too much of this hormone. When this occurs we can see symptoms such as increased appetite, increased water intake, increased urination, hyperexcitability, staying up and being active through the night, to name a few. It's also important to know that internally they could have elevated blood pressure. Hyperthyroidism can also cause a certain type of heart disease called hypertrophic cardiomyopathy. So I would also recommend that you have your vet perform blood pressure testing and have a good listen to the heart for any possible murmurs. High blood pressure can cause other problems with cats such as retinal detachment resulting in blindness and it can promote kidney disease.
It's hard to understand by your question whether the thyroid hormone level is actually normal now. You say that the higher dose controlled the thyroid but now you're on a lower dose. I would recommend that a blood test be taken sooner than three months to figure out if the dosing is now suitable. Whenever I make a dosage change for thyroid disease, I always take a blood test 30 days later. It's possible that the lower dose is not controlling the thyroid disease but not controlling the symptom of being awake at night.
The other possibility is that this behavior through the night may not be caused by thyroid disease. I believe it probably is since you say it improved on the higher dose. However, it's important to consider other possibilities. Cats can do this behaviour when they have anxiety or fear. As our cats get older their senses diminish, so their eyesight, hearing and sense of smell can get worsen. This basically makes them feel less in control of their surroundings creating anxiety and confusion. You can speak to your veterinarian about pharmaceutical options to reduce anxiety and senility. I would only consider an anti-anxiety medication if it's clear that the thyroid disease is not the cause of it. Also, I would try supplements before going to medications because there are many out there that can show success and they could be less harmful.
Dr. Clayton Greenway
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