Joint supplements are a multi-billion dollar industry. But which ones actually work for dogs with arthritis? Here is what the science says about the most popular joint supplements for dogs.

Glucosamine and Chondroitin

The most commonly used joint supplements. Glucosamine is a building block of cartilage. Chondroitin helps cartilage retain water and inhibits enzymes that break down cartilage.

The evidence: Mixed but leans positive. Most studies show a modest benefit for some dogs, particularly when started early. The best evidence comes from veterinary-formulated products (Dasuquin, Cosequin) which have been tested in clinical trials.

Dosing: Glucosamine 500-1000 mg/day for a medium dog. Chondroitin 400-800 mg/day. Give with food.

Omega-3 Fatty Acids (Fish Oil)

The strongest evidence of any joint supplement. EPA and DHA have potent anti-inflammatory effects. A 2010 randomized controlled trial showed that dogs receiving high-dose omega-3s had significantly less pain, better weight-bearing, and required lower NSAID doses.

Dosing: 40-60 mg EPA per kg body weight per day. This is a high dose — most OTC fish oil supplements under-dose. Use a veterinary product or consult your vet for the right amount. Look for products that list EPA and DHA content, not just "fish oil."

Green-Lipped Mussel (Perna canaliculus)

A New Zealand shellfish rich in omega-3s, glycosaminoglycans, and unique anti-inflammatory compounds. Growing evidence supports its use, and it often works better than glucosamine alone.

Look for stabilized, cold-processed extracts. Not all green-lipped mussel products are equally effective.

Adequan (Polysulfated Glycosaminoglycan)

An injectable, disease-modifying osteoarthritis drug. Unlike oral supplements, Adequan has strong evidence of effectiveness. It inhibits cartilage-degrading enzymes and stimulates cartilage repair. Given as a series of intramuscular injections.

Undenatured Type II Collagen (UC-II)

A newer supplement. Small pilot studies suggest it may reduce pain and improve mobility. It works differently than glucosamine — it "trains" the immune system not to attack the body's own joint cartilage. Early evidence is promising but limited.

What Does NOT Work: MSM, Hyaluronic Acid (Oral), Turmeric

MSM (methylsulfonylmethane) has limited evidence. Oral hyaluronic acid is poorly absorbed. Turmeric/curcumin has anti-inflammatory properties in lab studies but bioavailability is extremely poor unless specially formulated.

The Hierarchy of Evidence (Best to Weakest)

Omega-3 fatty acids (strongest evidence), Adequan injections, glucosamine + chondroitin (veterinary brands), green-lipped mussel, UC-II (promising but limited data), and MSM or turmeric alone (insufficient evidence).

Joint supplements are ONE part of a multimodal arthritis management plan. Weight management, controlled exercise, physical therapy, and appropriate pain medications are essential.