New York: A diet pill for dogs has been given approval by the US regulator, the Food and Drug Administration.

This allows qualified US veterinarians to precribe it to pets who have a weight problem. It costs around £1 a day to administer.

Manufacturer Pfizer is also waiting for approval from the European Medicines Agency.

The new drug called Slentrol, which is given in liquid form, is said to reduce a dog’s appetite and fat absorption and was shown to reduce weight by 18% and 22% in a clinical trial. But it can have side effects including diarrhoea.And it must not be taken by humans as it can cause liver damage.

Veterinarians estimate that about 40% of dogs in Britain and America are overweight. A survey last year found 81% of British vets considered obesity to be the biggest health threat facing dogs. It is linked with similar problems to humans such as heart disease and obesity.

In the US trials dogs lost about 3% of their weight a month without changing their diets.