Pharmaceutical agents

In humans, diet and exercise are the main methods of achieving weight loss, but some patients require drugs to help maintain the loss.

Drugs used to aid in obesity management include intestinal lipase inhibitors (e.g., orlistat), drugs that inhibit reuptake of noradrenalin and serotonin (e.g., sibutramine) and cannabinoid-receptor antagonists (e.g., rimonabant).

However, a range of side effects are seen with all medications, and this can limit their overall benefit.

Recently, two drugs were approved to assist in the management of obesity in dogs. Both are microsomal triglyceride transfer protein inhibitors that block the assembly and release of lipoprotein particles into the bloodstream.

Dirlotapide can be used as sole therapy for obesity for up to 12 months. It acts partly by preventing lipid absorption and partly by reducing appetite. Its effect appears to be a local one in the gastrointestinal tract; a similar effect does not occur when the drug is administered intravenously.

The effect on satiety avoids the need for a dietary change and eliminates negative behaviors that can lead to poor compliance with a weight-loss regimen. The most common side-effect is vomiting, which can occur in up to 20 percent of dogs using the drug.

While on the drug, weight loss is highly successful. However, a predictable rebound occurs when the drug is discontinued.

Mitratapide is a drug recently approved to aid in weight loss. It has both local (gastrointestinal) and systemic effects. It is designed for short-term use in conjunction with dietary management and behavioral modification.

Monitoring weight loss

In addition to these strategies, it is essential to supervise closely the whole weight-reduction regimen. This is labor-intensive, requires some degree of expertise and training in owner counseling and often requires a dedicated member of staff.

Nevertheless, correct monitoring is the single most important component to the weight-loss strategy. A recent study demonstrated that weight loss is more successful if an organized approach is followed with regular weigh-in sessions.

It is essential to continue to monitor body weight after ideal weight has been achieved to ensure the weight that was lost is not regained.

As with humans, a rebound effect has been seen in about 50 percent of dogs after weight loss.

Dr. Hoskins is owner of Docu-Tech Services. He is a diplomate of the American College of Veterinary Internal Medicine with specialities in small animal pediatrics. He can be reached at (225) 955-3252, fax: (214) 242-2200 or e-mail: jdhoskins@mindspring.com