Feline Hyperthyroidism

The condition of hyperthyroidism (overactive thyroid) is a very common finding in elderly cats, although we occasionally see it in cats from about 7 years old.

This is due to a usually-benign tumour in one or both of the thyroid glands which produce an excess of thyroid hormone. This increases the body’s metabolic rate and in turn causing the heart, liver and kidneys to work harder, resulting in a variety of symptoms. There are a several treatments and so in the vast majority of cases, we can control the situation well.

What are the signs of an overactive thyroid?

There are a variety of symptoms, and not all cats will show them. Some cats, especially early on, will show no worrying signs, but we may have our suspicions when they come in for their health checks.

A good appetite: This is one of the more common signs. Initially these cats eat well, then eat even better, then can start to wake their owners at night for yet more food! Understandably, many owners view a good appetite as a sign of good health, but may not be aware of the underlying cause.

Bright, happy and active: Many of these cats appear to be in positive good health in the earlier stages, so do not worry their owners.

Long nails and unkempt coat: But elderly cats don’t always groom well anyway…

Weight loss: The weight loss can often be despite eating very well. It can be hidden initially, or be set aside in our minds as just a sign of ageing.  However in time the weight loss becomes extreme

Intermittent diarrhoea or vomiting: This can be just occasional and not worrying, or can be frequent, as the excess thyroid can affect the gut or eating a lot causes them to bring food back.

Heart problems: These are more difficult to spot at home and can be quite advanced before there are any signs to notice. Cats can slow down- but as most elderly cats sleep 23/24 hours a day-who can spot this one! You may appreciate their heart racing, especially if they have lost weight. They may start to breath more heavily, They need seeing urgently.

How do we diagnose hyperthyroidism at the surgery?

Firstly we need you to bring in your happy, well eating, elderly cats. Our suspicions are raised from their history, examination including their heart rate and often we can feel a lump in their necks even if it is tucked away. Confirmation is usually made with a blood sample, running one (or occasionally two tests) for diagnosis of the thyroid problem, plus looking at other effects on the body.

What are the treatments?

The type of treatment will depend on each cat and their owners’ requirements, and can be altered depending on their response or ease. The aim of the treatment is to return the body to as normal a state as possible and so alleviate the symptoms.

Tablet medication: This is the most common form of treatment. Given time, the tablets block the effects of the excess thyroid hormones on the body. Further blood samples* will be needed to set and maintain the correct levels. The medication is life-long. Once the level has been assessed and we are all happy with the results, you may order a repeat supply of medication (please try to give us 24-48 hours notice so we can have them ready for you). We shall need to see each stable case at least every 6 months.

IMPORTANT: Monitoring blood samples may need to be  taken 4-6 hours after a tablet depending on which type, so check with the surgery, please.

Surgery: It is possible to surgically remove the thyroid gland(s). This is more commonly done on the younger cats, on cats that are very difficult to give tablets, and some cats when their owners do not want to give long term medication. The pros and cons of surgery must be carefully evaluated and discussed for each individual case before a decision is made.

Radioactive isotopes: These can be used to treat the cases very successfully. However, this must be done in a licenced unit and cats are required to stay there for several weeks. Unfortunately we cannot do this, but can refer cats if you so wish.

Diet: Hills have brought out a new diet called Y/D which is looking to be a useful alternative to tablet medication. Cats still need regular monitoring, but the responses so far have been good. It is proving to have good palatability, and with special advice can be fed in a multicat household.