In this AnimalWised article we are going to talk about methimazole for cats, a medication that veterinarians prescribe for cats suffering from hyperthyroidism. When used correctly, this medication is very useful. However, one must follow their veterinarian’s guidelines to use it safely and avoid any side effects.
What is methimazole?
Methimazole is a thionamide derivative and part of the pharmacotherapeutic group of antithyroid drugs. As the name suggests, it is used to treat hyperthyroidism, a disease characterized by an overactive thyroid gland that produces more hormones than normal. Methimazole works by inhibiting hormone synthesis. In as little as 1-3 weeks, it can reduce T4 levels. Methimazole for cats is rapidly absorbed and
What is methimazole for cats good for?
Methimazole is a medication used specifically for hyperthyroidism in cats. If your cat is diagnosed with this disease, the veterinarian may prescribe methimazole for one of the following reasons:
– To stabilize thyroidism before proceeding with thyroid gland removal.
– To treat hyperthyroidism in the long term, keeping in mind that this disease is not curable. In this case, other options are considered, such as surgical thyroidectomy or treatment with iodine.
It’s important to remember that hyperthyroidism is more common in older cats. It’s usually caused by benign or malignant thyroid disorders, and it can present in a severe way. Symptoms to look out for include marked weight loss, increased appetite and thirst, hyperactivity, tachycardia, poor coat appearance, diarrhea or vomiting. If your cat is over seven years of age, it’s recommended that you take them for a veterinary check-up at least once a year, so that any potential diseases can be detected early.
Methimazole dosage for cats
We have found that methimazole comes in both coated tablets and oral solution, so we can choose the best presentation for our cat. Both for stabilization before surgical thyroidectomy and for long-term treatment of hyperthyroidism, the starting dose will be the same, at about 5 mg per day.
It is recommended to give methimazole to the cat with food and divide the dose into two doses, one in the morning and one in the afternoon. However, this starting dose is only indicative and may need to be adjusted according to your cat’s reaction.
Only the vet can decide how much methimazole our cat needs. Try to always give the lowest dose possible that still achieves the desired effect. In any case, more than 20 mg per day is never prescribed. Transdermal methimazole is also a good option for cats that don’t accept the drugs orally or that cause digestive discomfort. You only have to apply it to the inner area of the ear. Learn more in our article about how to give a cat a pill.
Cats treated with methimazole must have access to a sufficient amount of water at all times, as this drug can lead to concentration of the blood. If your cat is on this medication, it is important to only give them the drugs prescribed by the veterinarian and to always follow up with regular blood tests, as an overdose can be fatal.
Contraindications of methimazole for cats
The following cats should not take methimazole:
– Cats with systemic diseases such as diabetes or liver failure
– Cats with autoimmune diseases
– Cats with alterations in white blood cells
– Cats with a platelet alterations or clotting problem
– Pregnant and nursing cats
– Cats taking any other medication (vaccines included) – the veterinarian must be made aware of all other medications the cat is taking to ensure no interactions occur
– Cats with an allergy to the active ingredient in methimazole
Remember that some other cats, like those with kidney disease, can only use methimazole if the vet carefully weighs the pros and cons of both administering the drug and not. This is because methimazole reduces glomerular filtration, so if you decide to medicate, it’s essential to closely monitor the cat’s kidney function.
Side effects of methimazole for cats
If you notice any discomfort in your cat or a fever, it’s important to notify your vet right away. In these cases, a blood test for hematological and biochemical analysis will be necessary. If a problem is diagnosed, the vet will prescribe the appropriate medication to control it.
Although methimazole is usually well tolerated in cats, there have been reports of adverse effects. These effects are usually mild and resolve on their own without the need to stop treatment. In more severe cases, the medication will need to be stopped and an alternative treatment found. However, adverse reactions are considered to be rare. These include the following:
- Loss of appetite
- Intense itching
- Irritations in the head and neck area
- Jaundice (yellowing of the skin and mucous membranes)
- Hematologic abnormalities
- Hypothyroidism (rare with high doses)
Methimazole for cats is a safe and effective treatment for feline hyperthyroidism, however it is important to make sure that it is prescribed by a veterinarian who has fully analysed your cat’s condition and made sure they are not allergic to its active ingredient. Follow their guidelines precisely to avoid overdose or side effects.