The combination of glucosamine and chondroitin has been shown to have a synergistic effect. This means that the effect of the combination is greater than the sum of each agent alone, 1 + 1 = 3. This combination both stimulates cartilage production and inhibits cartilage damage, providing a true chondro-protective effect. This combination of agents has been shown in clinical trials with horses, dogs and humans to have beneficial effects in reducing the symptoms of joint disease.