Last week I wrote about conditions in older cats which caused appetite and weight loss.

This week, I would like to explain about another condition in older cats where they also lose weight but with this condition there is a noticeable increase in appetite.

The condition results from an overactive thyroid gland and is known as hyperthyroidism.

The thyroid gland is located in the neck – just below the adam’s apple. It produces a hormone called thyroxine which controls the rate of metabolism. Cats are prone to getting a benign tumour in the thyroid gland which makes the gland swell. The swelling in the neck can often be felt by the vet. Normally the production of thyroxine by the thyroid gland is controlled very strictly by part of the brain but the tumour in the thyroid acts outwith the bodies normal control mechanisms and excessive volumes of thyroxine are produced.

The excessive thyroxine means that the bodies metabolic rate is increased. Cats eat more because their metabolism is increased but they often lose weight because they burn up their food even faster than they can take it in. Often hyperthyroid cats are restless and hyperactive. Sometimes they can become aggressive and their heart rate is increased.

Over a period of time, the increased stress on the metabolism can lead to secondary heart, liver or kidney problems.

Hyperthyroidism can be diagnosed with a simple blood test. At Donaldson’s we have a lab analyser which can measure thyroxine so we can often get results from a blood sample within an hour.

Most cats with hyperthyroidism can be treated very effectively with medication. Despite the fact that they are often old cats and sometimes they can be very thin because of the thyroid problem, they usually respond very well to tablets.

In cats where daily tablets are difficult, we can operate and remove the offending part of the thyroid gland. Operating on such old cats is always a difficult dilemma but the results tend to be very good.

The secondary heart, liver or kidney problems can be very much more difficult to treat so prompt diagnosis and treatment are essential.