Side Effects of Glucosamine for a Dog

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Side Effects of Glucosamine for a Dog
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Glucosamine is used to improve the quality of life for dogs with arthritis. This shellfish derivative has the benefit of being inexpensive and readily available. Its many forms make it convenient to administer to different breeds of dogs. In addition, glucosamine has a relatively small number of side effects, all of which are easily treatable. As a result, glucosamine is thought to be a safe and convenient treatment for a wide variety of dogs.


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Glucosamine Facts

Glucosamine is a naturally occurring substance found in joint cartilage. According to, as the body ages, the production of glucosamine decreases and osteoarthritis may occur.

Glucosamine used in supplements is found in crustacean shells, in a substance called "chitin." According to Drs. Foster and Smith, "because the shells are often discarded, (they) provide a reliable and cost effective source of glucosamine."


Osteoarthritis symptoms include difficulty walking, lethargy, difficulty getting up from a sitting position, and a lack of desire to be touched, among others (See References 1). Dogs that show these symptoms should be taken to the vet to rule out arthritis or other injuries.

A dog must continue to take glucosamine all of its life in order for the relief it experiences to continue. Glucosamine supplements do not cure any effects of arthritis; they merely return the level of glucosamine in the body to approach what was formerly normal (See References 1 and 2).


Glucosamine therapy is commonly used in Europe. It is growing in popularity in North America, although veterinarians may not yet prescribe such therapy for their patients.

Glucosamine Side Effects

Few side effects occur when treating a dog with glucosamine. With rare exceptions, they are mild and easy to treat.

Mild side effects of glucosamine include vomiting, abnormal stool production (either diarrhea or constipation), and drowsiness, among others.


Severe side effects include allergic reactions if the dog is allergic to shellfish, a blood-thinning effect if the glucosamine is paired with chondroitin, or heightened blood sugar levels.

Symptoms of an allergic reaction may be as mild as the dog chewing at its feet or as severe as anaphylactic shock. Anaphylactic shock requires treatment by a veterinarian.

Treatment of Glucosamine Side Effects

Decreasing the effect of side effects may be as simple as reducing the amount being given or giving the supplement with food.


Dogs beginning glucosamine treatment may require high doses of the supplement for it to have any positive effect. Dogs that experience symptoms such as reduced appetite or gastrointestinal complications may find them lessened when the dosage is reduced.

Glucosamine made from corn or other plant products is available for dogs that have shellfish allergies; however, this kind of glucosamine is more difficult to find than the shellfish product.

Remove dogs from painkillers or reduce the amount of painkillers that the dog is taking when starting a glucosamine regimen in order to avoid potential complications.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.