This condition commonly affects older cats in the UK, and can often be inaccurately associated with aging by owners, as the clinical signals often appear gradually and often are interpreted as cat ageing.

The condition typically affects older cats from 11 years onwards, and is usually manifested by weight loss, and poor coat condition. Usually these older cats have good and often ravenous appetites and if they use a litter tray, they are intermittently noted to have diarrhoea.

On clinical examination by your veterinary surgeon, the condition is usually easy to identify. Often a nodule is palpable in the lower neck region, in the location of the thyroid tissue, and these cats have resting heart rates far higher than normal cats at the clinic.

A simple blood test is usuallly all that is necessary to confirm the condition and the disease is very treatable.

The condition occurs when the thyroid tissue develops a tumour or cancer, which causes the overproduction of thyroid hormone, which in turn increases the metabolic rate.

This means effectively that the cat looses weight despite often eating more as absorption of food from the intestine is reduced.

Diarrhoea is often the result, but as many cats affected with the condition are outdoors, this goes unnoticed by the owner.

Treatment of the condition, is usually simple, and reverses the disease signals, and improves quality of life.

Two common treatments are available:

  • Medical management- involves daily medication to reduce the formation of thyroid hormone
  • Surgical management- involves usually simple surgery to remove the cancerous thyroid tissue from the neck

Most owners successfully medicate their cats to control this disease, though some owners find the task onerous and their cat too difficult to medicate and opt for surgical treatment.

Radiation treatment is an expensive option available in the UK at a small number of centres, but involves confinement in radiation protective environment for several weeks after radioactive drugs are given that destroy the cancerous thyroid. For this reason, this treatment is rarely performed.

Untreated the condition causes cardiac disease, which may prove fatal in some cases. High blood pressure, is a frequent occurrence in hyperthyroid cats, and can lead to retinal haemorrhage and consequent blindness. Renal failure may often be associated with long term high blood pressure.

This condition is common in older cats, easy to diagnose, and very treatable. Although there are many causes of weight loss in older cats this condition must be considered, rather than assuming you old cat is just getting older!