Glucosamine for Dogs

Glucosamine Is a Popular Supplement for Dogs

Veterinarians often recommend glucosamine for dogs who have mobility or joint issues. An amino sugar, glucosamine is a precursor to glycosaminoglycans, which are precursors to cartilage.¹ In theory, giving glucosamine is a way to give the body the “ingredients” needed to build cartilage.

Commercially glucosamine is most commonly produced from shellfish exoskeletons. Vegetable-derived glucosamine can also be created through the fermentation of corn and wheat, though this version may not be as well absorbed.^{4, 5}

Glucosamine is a very popular supplement. It can be purchased in various formulations of tablets, capsules, powders, chews, and injectables, sometimes in combination with other supplements. Most joint supplements for dogs contain glucosamine along with other beneficial substances, especially chondroitin sulfate. Some common joint supplement brands include Dasuquin®, Glycoflex®, and Cosequin®.

Glucosamine is also sold under the names of glucosamine sulfate, glucosamine chondroitin, glucosamine hydrochloride, N-acetylglucosamine and polysulfated glycosaminoglycan.

Evidence for Glucosamine’s Efficacy

Glucosamine is considered to have anti-inflammatory properties via several pathways. ² Supplementing glucosamine could improve the symptoms of arthritis by slowing cartilage breakdown and reducing swelling in the joints.

Glucosamine Studies in Dogs

There is a type of glucosamine you can only get at the veterinary office because it is administered as a shot. Adequan® is an injectable polysulfated glycosaminoglycan that is FDA approved (and recommended by many veterinarians) for the treatment of osteoarthritis in dogs and horses.⁶ In fact, it is the only FDA-approved disease-modifying drug clinically proven to inhibit cartilage loss in dogs with osteoarthritis.

Giving glucosamine by mouth along with chondroitin has long been recommended by many veterinarians, but high-quality studies on oral delivery are limited and often show conflicting results.

• A 2007 randomized and double-blinded study of 35 dogs did find that the dogs taking glucosamine and chondroitin had statistically significant improvements in pain scores and weightbearing.⁸
• However, a 2017 review that compiled studies evaluating the use of glucosamine and chondroitin in dogs concluded that the benefit of these agents for dogs with osteoarthritis is still questionable.⁹

Part of the challenge is that studies have varied so widely in their parameters that it is difficult to compare them.

The good news is that glucosamine is generally well-tolerated and is unlikely to harm your dog.⁹

Other Studies

Studies in humans have also shown conflicting results.

The National Institute of Health conducted the largest clinical trial on the subject to date, the 2006 Glucosamine/Chondroitin Arthritis Intervention Trial. It included about 1,600 people with osteoarthritis of the knee and found that while it did not significantly reduce pain in the overall group, it did appear to lessen symptoms in those patients with moderate to severe OA.³

In most of Europe, glucosamine is approved as a medical drug and recommended as a safe treatment option for osteoarthritis.

In the United States glucosamine is not approved by the FDA for medical use in humans. It is classified as a dietary supplement meaning that as long as it is not marketed as a treatment for a medical condition, companies must only provide evidence for safety, not efficacy.⁴

Some studies suggest a possible therapeutic effect of glucosamine and chondroitin in the treatment of inflammatory bowel disease and colorectal cancer in humans, but at this time the evidence is not felt to be compelling. ²

Common Uses for Glucosamine

Glucosamine is commonly used in dogs for joint support. Even though studies are largely inconclusive, anecdotally many owners and veterinarians feel that dogs and patients have benefited from glucosamine.

• It has anti-inflammatory properties and may delay cartilage breakdown.
• Glucosamine may decrease the amount of prescription medications needed to manage osteoarthritis. This is generally considered a good thing, because some of these prescription medications may have side effects on the gastrointestinal tract, liver, kidneys, or cause sedation.

At this point in time this supplement does not appear to directly benefit dogs with cancer, unless they also have osteoarthritis.

Glucosamine for Dogs Safety and Side Effects

Glucosamine products are generally well tolerated in dogs.

Side effects may include:

• Mild gastrointestinal symptoms such as soft stool and flatulence which generally improve after a few doses
• Possible hypersensitivity reactions for dogs with shellfish allergies

At high doses it may cause increased drinking and urination. Lethargy, injection site pain, and abnormal bleeding have been reported with injectable polysulfated glycosaminoglycan formulations such as Adequan.⁶

Can Glucosamine Be Given With Other Drugs and Supplements?

Glucosamine appears to be safe to combine with most medications; however, it may interfere with certain chemotherapeutics (cancer treatments), blood thinners, or treatments for diabetes.⁷

When to Not Use Glucosamine

Glucosamines should be avoided or used with caution in several situations.

1. Patients receiving anticoagulants such as warfarin, heparin, and rivaroxaban, as it could increase the anticoagulant effects of these drugs.
2. Dogs receiving injectable or oral treatments for diabetes such as insulin or glipizide, as it may decrease efficacy of those drugs.
3. Dogs receiving certain chemotherapeutics like doxorubicin, as the glucosamine may make the chemo less effective.
4. During pregnancy or lactation, as there is not enough reliable information about its safety in reproduction.⁷

It is always a good idea to check with your veterinarian before adding any supplement, but this is especially important if your dog is diabetic or on chemotherapy.

How to Give Glucosamine

If you decide to try a glucosamine supplement, be sure to choose a reputable product that has been tested in dogs. Consult with your veterinarian or the manufacturer’s label for specific information about dosing for that product. Some products may recommend a higher “loading dose” for the first few weeks and then decreasing to a lower dose for long-term maintenance. Generally, doses range in the 15-30 mg/kg/day range to start, and drop down to 7.5-15mg/kg/daily or every other day after a month or so.

Bioavailability is low and there is controversy about whether certain formulations work better than others, but both glucosamine hydrochloride and glucosamine sulfate can be absorbed through the gastrointestinal tract.⁷

What If I Miss a Dose?

If you miss a dose check with the manufacturer of the specific product you are using, or your veterinarian. Generally speaking, it is safe to resume your regular dosing schedule at the next normal time.

Storage and Handling

Follow manufacturer guidelines for the product that you are using.

Our Take

At this time, glucosamine cannot be recommended as a cancer treatment or for cancer prevention, but it is, however, worth asking your veterinarian about a glucosamine supplement from reputable sources if your dog has osteoarthritis. Although the studies are conflicting, it is generally safe and glucosamine side effects for dogs are low. It does improve the quality of life for some dogs, which is ultimately what it’s all about!