The US Food and Drug Administration (FDA) has announced the approval of Slentrol (dirlotapide), a prescription drug for the management of obesity in dogs.

Slentrol reduces appetite and fat absorption to produce weight loss. A veterinarian will determine whether the dog should be treated, based on the dog's weight and general health.

"This is a welcome addition to animal therapies, because dog obesity appears to be increasing," said Stephen Sundlof, D V M, PhD, director of FDA's Centre for Veterinary Medicine. "Veterinarians are well aware that overweight pets are at a higher risk of developing various health problems, from cardiovascular conditions to diabetes to joint problems."

Veterinarians generally define a dog that weighs 20 per cent more than its ideal weight as obese. Surveys have found that approximately 5 per cent of dogs in the US are obese, and another 20-30 per cent are overweight.

Slentrol is a new chemical entity, called a selective microsomal triglyceride transfer protein inhibitor, which blocks the assembly and release of lipoproteins into the bloodstream. The mechanism for producing weight loss is not completely understood, but seems to result from reduced fat absorption and a satiety signal from lipid-filled cells lining the intestine.

The drug is given to the dog in varying amounts over the course of the treatment. The dog is given an initial dose for the first 14 days. After that, the veterinarian will assess the dog's progress at monthly intervals, adjusting the dose depending on the dog's weight loss. After the dog has achieved the goal weight, the drug's manufacturer recommends continued use of the drug during a three-month period, while the veterinarian and dog owner establish the optimal level of food intake and physical activity needed to maintain the dog's weight.

Adverse reactions associated with treatment with Slentrol include vomiting, loose stools, diarrhoea, lethargy and loss of appetite.

To discourage human use, the label of Slentrol includes the standard warning, "Not for use in humans. Keep this and all drugs out of reach of children," and cites adverse reactions associated with human use, including abdominal dissention, abdominal pain, diarrhoea, flatulence, headache, nausea and vomiting.

Pfizer Inc., New York, manufactures Slentrol.