Adequan is an injectable drug that slows cartilage breakdown and supports joint repair in dogs and horses with arthritis. Its active ingredient, polysulfated glycosaminoglycan (PSGAG), is a compound derived from animal cartilage that closely resembles molecules already found in your pet’s joints. Unlike oral joint supplements that primarily manage symptoms, Adequan reaches joint tissue directly through the bloodstream after intramuscular injection.
What Adequan Does Inside the Joint
Healthy joints depend on a balance between building up cartilage and breaking it down. Arthritis tips that balance toward destruction. Adequan works on both sides of that equation, slowing the damage while encouraging repair.
On the protective side, PSGAG inhibits several destructive enzymes that chew through cartilage in arthritic joints. These include a group called metalloproteases, along with enzymes known as stromelysin and elastase. It also reduces levels of a key inflammatory molecule (prostaglandin E2) that drives pain and swelling. By dialing down these catabolic processes, Adequan helps preserve the cartilage that remains.
On the building side, PSGAG stimulates joint cells to produce more of the raw materials cartilage needs. Studies on cultured cartilage cells show increased production of proteoglycans (the sponge-like molecules that give cartilage its cushioning ability), collagen (the structural fiber that gives cartilage strength), and hyaluronic acid. That last one matters especially because hyaluronic acid is the primary component of synovial fluid, the slippery liquid that lubricates the joint. Synovial membrane cells exposed to PSGAG show a specific boost in hyaluronic acid production, which can improve the thickness and lubricating quality of joint fluid.
The exact mechanism behind all of this isn’t fully mapped out. Researchers know what PSGAG does in lab settings, but the precise pathways it uses inside a living joint are still not completely understood.
FDA-Approved Uses
Adequan exists in two separate formulations approved for different species. Adequan i.m. is FDA-approved for horses with noninfectious degenerative or traumatic joint dysfunction and associated lameness, specifically in the carpal (knee) joint. Adequan Canine is approved for dogs with signs of noninfectious degenerative or traumatic arthritis in synovial joints.
Both formulations are prescription-only and given by intramuscular injection. There is no oral form of Adequan. While veterinarians sometimes use it off-label for other joints or species, the FDA approvals are specific to the conditions listed above.
How the Injection Schedule Works
The treatment protocols differ between dogs and horses, but both follow a structured loading phase designed to build up the drug’s effects in joint tissue.
For dogs, the standard protocol is one injection twice per week for up to four weeks, totaling a maximum of eight injections. The FDA-approved dose is 2 mg per pound of body weight per injection. Many veterinarians then transition to periodic maintenance injections at longer intervals, though the specific maintenance schedule varies by practice and the individual dog’s response.
For horses, the recommended protocol is 500 mg injected every four days for 28 days, which works out to seven injections during the loading phase. As with dogs, some veterinarians recommend ongoing maintenance injections afterward, but the FDA labeling does not specify a maintenance schedule beyond the initial 28-day course.
Safety and Precautions
Adequan is structurally similar to heparin, a natural blood-thinning compound. At the approved dose for dogs, safety studies indicate adverse effects are unlikely. However, at higher doses or longer treatment periods, effects on blood clotting, kidney function, and liver function become possible. Dogs with known or suspected bleeding disorders, kidney problems, or liver disease should be treated with extra caution.
For horses, the labeling notes that Adequan should not be mixed with other drugs or solvents, and its safety has not been established in breeding animals. It is not approved for use in horses intended for food.
The most common side effects pet owners notice are mild soreness at the injection site and occasional digestive upset. Serious reactions are rare at recommended doses.
How Adequan Differs From Oral Joint Supplements
Many pet owners wonder why they can’t just use glucosamine or chondroitin supplements instead. The key difference is delivery. Oral supplements pass through the digestive system, where absorption is inconsistent and the amount that actually reaches joint tissue is debated. Adequan bypasses the gut entirely. Injected into muscle, PSGAG enters the bloodstream and concentrates in joint cartilage and synovial fluid.
The other major difference is what the compounds do once they arrive. Oral glucosamine provides a building block that cartilage cells can use, but it doesn’t directly inhibit the destructive enzymes driving arthritis. Adequan both supplies raw materials for cartilage repair and actively blocks the enzymes breaking cartilage down. This dual action is why veterinarians often recommend Adequan for moderate to advanced joint disease, where simply supplementing building blocks isn’t enough to keep up with the rate of cartilage loss.
Some veterinarians use Adequan alongside oral supplements or anti-inflammatory medications as part of a broader pain management plan, since each targets a different aspect of joint disease.