Adequan Equine is the brand name for polysulfated glycosaminoglycan (PSGAG), an FDA-approved injectable disease-modifying osteoarthritis drug (DMOAD) for horses. It is derived from bovine tracheal cartilage and is the only FDA-approved PSGAG product for intramuscular use in equine joint disease. Adequan Equine is distinct from Adequan Canine, which is formulated for dogs and should not be substituted.
Overview
PSGAG is a semi-synthetic glycosaminoglycan that has been shown to inhibit enzymes (including matrix metalloproteinases and interleukin-1) that degrade cartilage in arthritic joints. It also stimulates the synthesis of proteoglycans and hyaluronic acid by chondrocytes and synoviocytes, supporting cartilage repair and improving synovial fluid quality. These dual actions — inhibiting degradation and promoting repair — give PSGAG its disease-modifying classification, distinguishing it from purely symptomatic treatments like NSAIDs.
PSGAG reaches therapeutic concentrations in joint tissues within 2 hours of intramuscular injection and has been detected in articular cartilage for up to 96 hours post-injection.
Uses
- Degenerative joint disease (DJD) / Osteoarthritis — FDA-approved indication
- Non-infectious arthritis — traumatic and degenerative synovitis
- Carpal joint disease — especially common in racehorses
- Post-arthroscopic surgery — to support cartilage recovery
- Hock, stifle, fetlock, and coffin joint disease — common sites of equine OA
- Intra-articular use — off-label but widely practiced by equine veterinarians
Dosage
Your veterinarian will determine the appropriate protocol.
| Route | Dose | Frequency | Duration |
|---|---|---|---|
| Intramuscular (FDA-approved) | 500 mg IM | Every 4 days | 7 treatments (28-day course) |
| Intra-articular (off-label) | 250 mg per joint | Single injection or series | As directed by vet |
The labeled IM protocol consists of 500 mg intramuscularly every 4 days for a total of 7 injections. Many veterinarians also administer periodic maintenance injections (e.g., monthly) after the initial loading course, though this is off-label. Intra-articular use is common in equine practice and may be combined with other intra-articular therapies such as hyaluronic acid or corticosteroids.
Side Effects
| Common | Serious (Contact Your Vet) |
|---|---|
| Mild injection site soreness (IM) | Joint flare (intra-articular use) |
| Transient joint effusion (IA use) | Signs of joint infection (heat, swelling, severe lameness after IA injection) |
| Prolonged bleeding or bruising | |
| Allergic reaction (rare) |
Adequan is generally well tolerated. The most common side effect from IM injection is mild soreness at the injection site. With intra-articular use, transient synovial effusion may occur. PSGAG has heparin-like properties and may prolong bleeding times; this is clinically significant in horses with bleeding disorders or those undergoing surgery.
Drug Interactions
- Anticoagulants (heparin, warfarin): PSGAG has mild anticoagulant properties; concurrent use may increase bleeding risk.
- NSAIDs (phenylbutazone, flunixin, firocoxib): Commonly used concurrently for multimodal pain management; no direct adverse interaction.
- Intra-articular corticosteroids: Often combined in IA protocols; no known adverse interaction, but joint sepsis risk applies to all IA injections.
- Hyaluronic acid (Legend): Frequently combined with PSGAG for synergistic joint support.
Contraindications
- Known bleeding disorders or coagulopathies
- Active joint infection (septic arthritis) — PSGAG should not be injected into an infected joint
- Known hypersensitivity to PSGAG or bovine-derived products
- Use with caution in horses scheduled for surgery (bleeding time concern)
Storage
- Store at controlled room temperature, 59-86 degrees F (15-30 degrees C).
- Protect from light.
- Do not freeze.
- Use single-dose vials promptly; discard unused portion.
Frequently Asked Questions
How long does it take to see results with Adequan? Some horses show improvement after 2-3 injections. The full benefit of the 7-injection loading course is typically evaluated after the series is complete. Individual responses vary.
Is Adequan Equine the same as Adequan for dogs? No. Adequan Equine and Adequan Canine contain the same active ingredient (PSGAG) but are different formulations with different concentrations and approved doses. Always use the species-appropriate product.
Can Adequan be used with joint injections? Yes. Many veterinarians combine IM Adequan with intra-articular therapies such as hyaluronic acid, corticosteroids, or IRAP/PRP. Your veterinarian will design the best multimodal joint management plan.
Is Adequan allowed in competition horses? Regulations vary by discipline and governing body. PSGAG is generally not prohibited, but rules change. Check with your competition organization and veterinarian.
Does my horse need the full 7-injection series? The FDA-approved protocol is 7 IM injections every 4 days. Completing the full series gives the best chance of achieving the disease-modifying benefits. Discuss the treatment plan with your veterinarian.
This information is for educational purposes only and does not replace professional veterinary advice. Always consult your veterinarian before administering any medication to your horse.