Estimates of numbers vary, but most experts agree that around 1 woman in 13 in the UK will have thyroid disease, with the figure increasing for older women. Figures being presented at the Birmingham meeting will show indicate that a tendency to thyroid disease is even more common in older cats.

In humans, low thyroid activity is common, but in cats having an overactive thyroid is a more common problem. Apart from humans, cats are the only species where non-cancerous hyperthyroidism has been recorded. Hyperthyroidism in cats was first reported in the late 1970s and has since been recognised as the most common hormonal disease of older cats.

Dr Jenny Wakeling’s research at the Royal Veterinary College (London), studied 100 cats over 8 years of age, visiting a veterinary practice for routine health checks. The thyroid hormone measurements were repeated after a period of about a year.

They found that in apparently healthy older cats – cats more than 8 years old – around 6% of cats had hyperthyroidism. In addition 20% had subclinical hyperthyroidism – in other words they had an abnormal thyroid function, but not the full-blown disease. However the research also showed that cats with subclinical hyperthyroidism had a high risk of becoming hyperthyroid within 18 months.

In 1999, Cats Protection estimated that there are 5 million domestic cats in the UK, not including stray and feral cats. It’s not known how many of these are more than 8 years old.

Dr Wakeling said:

“What this means is that around a quarter of older cats – older than around 8 years – will either have thyroid disease, or have a tendency to develop it. It’s something that owners need to keep an eye on.

“You tend to notice it if your cat is eating a lot but losing weight. Then you may pick up other symptoms, such as hyperactivity, fast heart rate, and a poor coat. You might also find that the cat gets stressed and angry more easily. This can easily be treated, and if in doubt you should take your cat along to your vet for a blood test. It’s not only humans who get hormonal problems.”