In 1999, glucosamine was the top-selling dietary supplement in the United States, with annual sales of US $288 million. It has become an immensely popular dietary supplement around the world.

It has proven itself again and again though its potential for repairing damaged joints and slowing the progression of arthritis.

Since glucosamine works so well for human arthritis, it is natural to ask: What about dog arthritis?" Is it safe? Is it effective?

The answer: Yes, it appears to be both safe and effective.

The main safety concern comes from animal studies in which large amounts of glucosamine were given to rats and other animals intravenously, for short periods of time. Under these extreme and usual conditions, glucosamine tended to decrease insulin levels and/or induce insulin resistance. When researchers tested humans with large amounts of intravenous glucosamine, the same thing happened. Hence a concern arose that glucosamine could cause diabetes or make diabetes worse.

Normal therapeutic doses of glucosamine given orally have never been shown to have an adverse effect on insulin levels, insulin resistance or blood sugar levels. Even in diabetic rats and type 2 diabetic humans, normal therapeutic doses of glucosamine taken orally have been shown to have no significant effect on insulin, insulin resistance or blood sugar levels.

Cosequin is the brand name of a glucosamine and chondroitin formulation made to treat dog arthritis, cat arthritis and horse arthritis. It is taken orally and appears to have an excellent safety record.

Cosequin has been seen to have an excellent safety profile. In safety studies, Cosequin given at twice label recommended levels for 30 days in healthy dogs had no adverse effects on blood sugar levels. No clinically significant effects were seen on any biochemical parameter in these studies.

Although no change in blood sugar control would be expected for a diabetic dog, as with the addition of anything new to a diabetic's regimen, it is advisable to monitor closely.