Although glucosamine and chondroitin are both used for the treatment of arthritis in animals and humans alike, they are actually natural dietary supplements and not medication. 
These supplements can be bought from pet supply catalogs and online stores quite readily. They are also available at health food stores and your local veterinary clinic. Many different forms of both supplements are available – glucosamine combined with chondroitin or glucosamine in pure form.
Maximum joint health for your dog is achieved by giving him glucosamine in the right form and quality. This is often combined with other ingredients such as minerals and vitamins. Joint health will ease the pain quickly and improve your pet’s quality of life greatly. Glucosamine for dogs has none to very few side effects, and thousands of dosages have been sold worldwide. The only known side effects are occasional diarrhea or vomiting. Reducing the dosage or giving the glucosamine with food, usually gets rid of these side effects totally. Glucosamine is found naturally throughout your dog’s body specifically in connective tissue, synovial fluid and cartilages.
Often when dogs and / or humans slow down, it is often ascribed simply to old age. It could however be due to a variety of reasons. Joints, ligaments, tendons and joint fluids wear with age and this is often the cause of the slowing down as the pain associated with arthritis, osteoarthritis and/or hip dysplasia can be severe. Before deciding that the slowing down is due to this, consult a vet and let him perform a thorough examination of your dog. If the problem is indeed caused by joint related pain, glucosamine and chondroitin supplements can be given to your dog, and the symptoms should improve dramatically. Many owners may not even identify a problem and simply view the loss of activity in their dogs as a result of old age. They would therefore not be aware that they can greatly assist their pet in old age by fiving them these supplements.
Glucosamine for dogs has been proven to be effective in relieving symptoms of not only arthritis, but also of a wide variety of problems including carpal tunnel syndrome and even help with skin wound-healing. Many different forms of Glucosamine and chondroitin are available such as Glucosamine sulfate and hcl to mention but two. As dogs typically hate having tablets shoved down their throat, liquid glucosamine for dogs is a lot easier to administer whilst remaining extremely effective. As with all products, not all glucosamine and chondroitin supplements are created equal. The best product need also not necessarily cost the most. One way to make sure that you get what you pay for is by comparing the ingredients between products. The difference in various products lies in the dosing, purity of the ingredients as well as the type and quantity of vitamins and minerals added. Ideally you should let a vet determine the correct glucosamine dosage for your dog.