Glucosamine sulphate (often just called glucosamine) is widely recommended for sufferers of joint problems (especially osteoarthritis) and is one of the most common non-vitamin, non-mineral, dietary supplements for both humans and dogs.
Most scientists believe that it helps to prevent the break down of the joint cartilage.
Glucosamine can be found naturally in animal bones and bone marrow and so is present in small amounts in all meat-based dog foods. Nevertheless, many dog foods, especially those designed for older dogs or large breed dogs, have added glucosamine to provide additional joint support.