Like people, many dogs suffer from arthritis, especially as they age. This painful condition occurs when cartilage, the cushioning between the bones, begins to thin and wear away and the ends of the bones start to rub against each other. It may be caused by trauma, disease, or wear and tear that comes with use over years.
While there is no cure for arthritis, some treatments can lessen pain and improve mobility.
What Is Glucosamine?
Glucosamine, a naturally occurring compound, is one of the more popular over-the counter arthritis therapies. It is one of several natural substances or nutraceuticals that are known as chondroprotective agents used in the treatment of arthritis in humans, dogs, horses, and other animals. In dogs it is also often used to:
- alleviate pain and joint wear in hip dysplasia or other structural problems;
- aid in the treatment of spinal disc injury;
- ease recovery from joint surgery;
- keep performance dogs in peak condition.
Glucosamine supplements are said to alleviate the symptoms of joint damage by boosting the repair of damaged cartilage, the moist, spongy material that forms a cushion between joints. Cartilage cells are constantly turning over, and when cartilage is damaged, the joint becomes inflamed and releases enzymes that cause more damage. This starts a cycle of joint degeneration.
In most commercial preparations, the substance is derived the shells of crabs, oysters, and shrimp or synthesized in laboratories from plant sources.
Glucosamine was isolated by German surgeon Georg Ledderhose in 1876. There are two common formulations—glucosamine hydrochloride and glucosamine sulfate.
This supplement is often used in conjunction with another natural substance, chondroitin sulfate, which helps cartilage retain water. Chondroitin is usually isolated from shark or cow cartilage.
These products are regulated as dietary supplements, not drugs, by the U.S. Food & Drug Administration (FDA). As such, they are not subjected to the same stringent FDA review and approval process as pharmaceuticals. Dietary supplements are evaluated for safety after they are on the market, mostly through "adverse event monitoring." The supplement has been used in veterinary practices in Europe and the U.S. for about 20 years.
Does Glucosamine Work?
No one knows exactly what the mechanism of action is, but the supplement, an amino sugar, appears to improve the synthesis of glycosaminoglycans, one of the building blocks of cartilage. This is the tough connective tissue that cushions bones at the joints. The theory is that the supplement somehow stimulates chondrocytes or DNA activity that protects against joint degradation.
Starting in the 1980s, scientists began investigating these products in an effort to try to prove whether really work, but so far there is still no consensus. Studies in humans have been inconclusive. In 2000, researchers from Boston University's School of Medicine Arthritis Center analyzed the results of credible clinical trials conducted between the 1960s and 1999. They found 37, of which 15 were worth analysis. The results, published in the Journal of the American Medical Association, concluded that "some degree of efficacy appears probable for these preparations." Since then, some studies have shown limited or no efficacy, while others suggest that they do help.
In 2012, another examination of studies in humans found that one form—glucosamine hydrochloride—had little effect, while another form—glucosamine sulfate—offered pain relief superior or equal to "the commonly used analgesic or nonsteroidal anti-inflammatory drugs." The scientists determined that "the question of the benefit of glucosamine treatment remains largely unanswered." But, they noted that because the supplements have "low and rare adverse effects, it represents a viable option for the management of OA." They also expressed the opinion that it could be useful in combination with drugs and other natural products.
There little in the way of veterinary research. In 2007, scientists at the College of Veterinary Medicine, University of Georgia, Athens, conducted a similar review of 16 clinical trials of treatments for osteoarthritis in dogs. There were 16 studies that looked at drugs, as well as supplements. They reported their results in the Journal of the American Veterinary Medical Association and found that preparations containing glucosamine provided a "moderate level" of comfort and was on a par with some prescription drugs.
Does Glucosamine Have Side Effects?
There have been a very few side effects observed in patients taking glucosamine, including:
- Allergies (specifically among those who are allergic to shellfish);
- Excessive thirst and urination (at high doses).
- Also, since it is a sugar-based substance, some veterinarians are wary about its use in dogs with diabetes.
How Do I Give My Dog Glucosamine?
Most available formulations of glucosamine for dogs are oral, such as flavored tablets, pills, powders, or liquids. Never give medications or supplements designed for humans to your dog. It is generally administered daily. These supplements are available in pet-supply stores, veterinarian's offices, and online sources.
You should consult with your vet for the correct dosage and schedule.
Glucosamine and chondroitin are also included in dog foods formulated for senior and performance dogs, many of whom are at risk for joint disease and injury.
It may take weeks to see improvement, and veterinarians recommend evaluating the effects of the treatment after your dog has been taking it for about three months.
Photo of elderly dog courtesy Barra Labradors