Hyperthyroidism in cats 

What causes hyperthyroidism?

Hyperthyroidism is when the thyroid gland becomes enlarged and overactive and produces too much thyroxine. This overproduction results in a ‘faster’ metabolism and a stimulation of the central nervous system leading to restlessness, increased activity or even aggression.

The change in metabolism affects many organs in the body causing them to work harder than normal. If left untreated, this could lead to heart or kidney failure and your pet becoming seriously unwell.

The good news is that hyperthyroidism is usually quite easy to diagnose with a simple blood test. If diagnosed, hyperthyroidism can be treated in a variety of ways which means your cat can carry on living a full and active life.

Cat's thyroid gland - normal & enlarged

Signs of feline hyperthyroidism

Feline hyperthyroidism can cause changes to the appearance and behaviour of affected cats - below is a list of signs to look out for:

• Loss of body weight or muscle tone over the back and hips
• Increased appetite 
• Poor coat condition 
• A change in behaviour or personality e.g., becoming anxious, nervous, irritable, less interactive, restless or even aggressive 
• Avoidance of warm places 
• Toileting more frequently
• Upset tummy or digestive problems
• Breathing faster or even panting   

If you notice any of these signs of hyperthyroidism, or you are concerned about your cat's health, always contact your vet as soon as possible 

Treatment

Treatment usually starts with a medication, which can come in a tablet, or in a liquid format - your vet can help you decide what would work best for you and your cat.

The active ingredients in the medication work to reduce the production of thyroxine to bring it down to normal levels and resolve the clinical signs your cat was showing.

Once on medication, your cat will need regular blood tests to monitor its ongoing response to treatment and ensure it continues to receive the correct dose. 

The long-term goal is to try and get your cat back to “normal” with no clinical signs of the disease.