In this article on our site we are going to talk about methimazole for cats, a medicine that veterinarians prescribe for cats suffering from hyperthyroidism. This disease that affects the thyroid gland can only be diagnosed by a veterinarian and, of course, only this professional is responsible for prescribing this drug and indicating what dosage is appropriate. On the other hand, cats that consume methimazole have to undergo strict veterinary monitoring.
Keep reading to find out what exactly this medicine is, what is methimazole for cats and what its possible side effects are.
What is methimazole?
Metimazole or thiamazole is a derivative of thionamide and belongs to the pharmacotherapeutic group of antithyroid preparations This name already allows us to anticipate what it is its function, which is none other than the treatment of hyperthyroidism, a disease in which the thyroid gland produces a higher than normal amount of hormones. Thus, methimazole acts by blocking the synthesis of these hormones. Specifically, in 1-3 weeks it reduces T4 values. Methimazole for cats is a drug that is rapidly absorbed and eliminated mainly in the urine.
What is methimazole for cats?
The indication for using this medicine is clear: hyperthyroidism. If our cat is diagnosed with this disease, the vet will prescribe methimazole in any of the following cases:
- Stabilize thyroidism before proceeding to remove the thyroid gland.
- Treat long-term hyperthyroidism, but you have to know that the disease is not cured, only the cat's condition is controlled. For this reason, other options are considered, such as surgical thyroidectomy or iodine treatment.
You should know that hyperthyroidism is more common in older cats, it is due to benign or malignant thyroid disorders and usually presents more or less severely. An accentuated weight loss, accompanied by an increase in appetite and thirst, hyperactivity, tachycardia, bad appearance of the coat, diarrhea or vomiting are signs that should make us go to the veterinarian. In addition, in cats over seven years of age, at least annual veterinary check-ups are recommended, precisely to detect this type of disease early.
Dosage of methimazole for cats
We find several formats of methimazole in coated tablets and in oral solution, so we can choose according to the presentation best tolerated by our cat. Both for stabilization prior to surgical thyroidectomy and for long-term treatment of hyperthyroidism, the starting dose will be the same, that is, about 5 mg per day
It is recommended to give the cat methimazole with food and divide the dose into two doses, one in the morning and one in the evening late, although it can also be given as a single dose. In any case, this starting dose is indicative. Only the vet can decide how much methimazole our cat needs. Always try to give the lowest dose that achieves the desired effect. In any case, more than 20 mg per day is never prescribed. There is also transdermal methimazole, which is a good option for cats that do not accept drugs orally or cause digestive discomfort. Just apply it to the inner area of the ear. Discover in this other article How to give medicine to a cat.
Cats treated with methimazole should have access to sufficient amounts of water 24 hours a day, as this drug can cause concentration of the blood, so they have to be well hydrated. If it is always important to give our cat only drugs prescribed by the veterinarian, in the case of methimazole it is crucial. In fact, depending on the dose prescribed, the cat will have to be monitored and regular blood tests will always be necessary.
In addition, before starting treatment, you should also have a blood test that includes measurement of the total serum T4 hormone. The dose is adjusted based on the result of this parameter and its evolution as the treatment continues.
Contraindications of methimazole for cats
There are some cats for which methimazole is not recommended. They are the ones found in these situations:
- Systemic diseases such as diabetes or liver failure.
- Autoimmune diseases.
- Alterations in white blood cells.
- Alterations in platelets or coagulation problems.
- Pregnancy and lactation.
- If the cat is taking any other medication and the veterinarian does not know it, it must be reported to ensure that no interactions occur. Immunizations also count.
- Of course, it is not suitable for cats allergic to this active ingredient.
Also, keep in mind that some other cats, such as those with kidney disease, will only be able to use methimazole once your veterinarian carefully weighs the pros and cons of both giving the drug and if it is not done. This is because methimazole reduces glomerular filtration, which is why, if you decide to medicate, it is essential to subject the cat to a strict control of its renal function.
Side Effects of Methimazole for Cats
First of all, if we notice discomfort in the cat or a fever, we must notify the veterinarian immediately. In these cases, a blood test must be done for hematological and biochemical analysis. If a problem is diagnosed, the veterinarian will prescribe the appropriate medication to control it.
On the other hand, side effects have been reported after administration of methimazole in cats, although they are usually mild and resolve spontaneously without requiring discontinuation of treatment. In cases where these are more serious, the medication will have to be discontinued. However, adverse reactions are considered to be rare. These include the following:
- Vomiting.
- Decrease or loss of appetite.
- Lethargy.
- Intense itching.
- Irritations on the head and neck area.
- Rash.
- Jaundice, which is the yellowish coloration of the skin and mucous membranes. It is associated with a liver problem.
- Hematologic abnormalities.
- If a high dose is administered, in addition to these signs, the cat may experience hypothyroidism, although this is rare.
