Osteoarthritis (OA)

Veterinary advice should be sought before applying any treatment or vaccine.

Osteoarthritis (OA)

Degenerative Joint Disease, Arthritis

Osteoarthritis (OA), also known as Degenerative Joint Disease (DJD), is the most common joint disease that affects horses, humans, and dogs. OA is a chronic, degenerative process characterized by progressive cartilage deterioration, loss of joint space, marginal osteophyte formation, subchondral bone remodeling, and inflammation of the joint tissues. These processes eventually lead to the breakdown of cartilage in the horse's synovial joint. The most common synovial joints affected in horses include the hock (where it is often referred to as bone spavin), the pastern (where it is called ringbone), the fetlock (called osselets), stifle and knee--and less commonly the neck and back.

Clinical Presentation

Once the joint cartilage begins to degrade, the bones rub together and can cause continued damage and pain. Signs may come and go, stay the same, or result in progressive deterioration of the articular cartilage. Clinical signs of OA most commonly include:
  • Lameness
  • Pain on flexion or palpation
  • Stiffness, which often improves with exercise
OA can occur in all types of performance and pleasure horses, of any age or breed. The disease begins many years before structural joint changes become detectable.

Probable Cause

Most horses develop OA from repeated strenuous exercise inducing mechanical strain or trauma to the joint, rather than a single traumatic event. Factors that contribute to faster onset of OA are training, conformation of the horse, shoeing, breed, use of horse, osteochondrosis lesions (osteochondritis dissecans, subchondral bone cysts), articular fractures, and history of trauma.


The main goal for treatment of OA is to reduce pain and prevent further deterioration of the joint by controlling inflammation. Treatment is most effective if it is started during the early stages of OA.


Pain during flexion of the joint
Mild to moderate lameness
Shortened stride
Reduced range of joint motion
Joint swelling
Mild heat felt during palpation of the joint


  • History
  • Clinical signs
  • Lameness exam
  • Radiographs - Detect changes to the bone.
  • Ultrasound - Used to detect fluid in the joint and can to evaluate some bone changes.
  • Computed tomography (CT) - Provides information on the bone changes and to evaluate cartilage.
  • Magnetic resonance imaging (MRI) - Can detect articular cartilage changes.



Non-steroidal anti-inflammatory drugs (NSAIDs)Phenylbutazone (bute), flunixin meglumine, Firocoxib (Previcox), ketoprofen, naproxen, and carprofenMost commonly administered orally or by injection.
Joint injectionsTreatments that are administered by your veterinarian intra-articularly (meaning injected directly into the affected joint
Interleukin-1 receptor antagonist protein(IRAP)a treatment that’s actually derived from the horse itself, using the serum from the blood and incorporating it into a commercial syringe containing glass beads that are used to stimulate production of IRAP and other proteins. The mixture is incubated, processed for 24 hours, and injected back into the horse. It is one of the more expensive treatments, but has proven to be highly effective.
Hyaluronic acid (HA)Administered into the joint intra-articularly by your veterinarian. HA is a natural component of synovial fluid which has been used in horses for treatment of OA for over 30 years. It has also shown to be effective when administered intravenously.
Hyaluronate sodium (Legend)Administered IV or IA to improve joint function in the knees and fetlocks.
CorticosteroidsOne of the most commonly-used treatments for horses with OA. Corticosteroids are fast-acting, long-lasting anti-inflammatories that have been used for over 50 years in horses. They are also one of the more cheaper forms of treatment of OA in horses.
Polysulfated glycosaminoglycans (PSGAGs), brand name AdequanAdministered in the muscle, with similar to compounds found in cartilage and has been shown to reduce inflammation.
Pentosan Polysulfate (PPS), brand name PentAussie Equine or genericAdministered IM
Topical creamdiclofenac sodium (Volteren)Penetrates through the skin into the joint. Can be applied by horse owners on a daily basis if needed.
Oral joint supplementsGlucosamine, chondroitin sulfate, avocado-soybean unsaponifiable extracts, methylsulfonylmethane (MSM), omega 3 fatty acids, super oxide dismutase (SOD), yucca, devil’s claw, garlic, vitamin C, etc.
Platelet Rich Plasma (PRP)
Gene Therapy with Interleukin-1 Receptor Antagonist (IL-1ra)
Mesenchymal stem cell therapy
Physical therapy


Scientific Research

General Overviews

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Risk Factors

  • Poor conformation
  • History of a developmental orthopedic disease

Horse Case Stories