Does Your Horse Have Osteoarthritis?

Osteoarthritis refers to an inflammation of a joint’s lining in combination with degenerative changes to the joint’s cartilage and underlying bone. It is a relatively common problem in the equine population. The condition is also known as arthritis, degenerative joint disease or DJD for short. Older horses are more commonly affected although arthritis can affect younger horses especially racehorses and performance horses.

Signs include lameness, stiffness, pain on flexion and effusion (increased fluid within the joint). Typically, horses present with a low grade lameness which may improve during exercise but worsens afterwards. Arthritis is often age related but may also result from previous injuries such as joint sprains, poor conformation and developmental bone conditions.

Osteoarthritis explained.

In a normal healthy joint cartilage covers the surfaces of the bones and helps them to slide over each other with minimal friction. A fibrous joint capsule surrounds the joint and contains synovial fluid – a straw coloured viscous fluid containing hyaluronic acid amongst other things which acts as a lubricant, rather like oil in an engine. In an inflamed joint the careful balance of joint fluid components becomes upset and the fluid becomes more watery in nature. An increase in the amount of inflammatory proteins causes degeneration of the cartilage. In extreme cases the cartilage erodes leaving exposed bone underneath. This in turn causes more inflammation and so the cycle of inflammation and degeneration continues. During movement, exposed bone surfaces rub over each other which cause’s pain. The volume of fluid in the joint also increases causing joint distension, another source of pain.

How is it diagnosed?

In some cases history and clinical examination may be sufficient to make a presumptive diagnosis.

Flexion tests (flexing the affected joint and trotting the horse off afterwards), nerve and/or joint blocks (local anaesthetic) may help to localise the source of the lameness.

X-rays help to ascertain the degree of damage within the joint; changes may include spurring at the edges of the joints, roughening of the joint surface and loss of density in the underlying bone. In severe cases fragments of bone may break off within the joint.

What are the treatment options?

  • Some mild cases can be successfully managed by adjusting exercise routines or reducing intensity.
  • Phenylbutazone (an anti-inflammatory) can be used to reduce inflammation within the joint and make the horse more comfortable.
  • Pentosan polysulphate, a joint protective agent, is injected into the muscle; it has an anti-inflammatory effect and helps to improve the quality of cartilage within the joint.
  • Nutraceuticals (feed supplements) such as glucosamine and chondroitin sulphate may help to improve the quality of cartilage and joint fluid.
  • Medication of affected joints with corticosteroids and/or hyaluronic acid can help to settle down the cycle of inflammation and pain within the joint. Other more recent osteoarthritis therapies include IRAP and regenerative medicines.


Remember, early detection of signs such as joint filling or stiffness is important as early treatment will help to avoid progression of the inflammatory and degenerative cycle. If you suspect your horse may be suffering from arthritis contact the team at SHEC or your local vet for more advice on investigation and treatment options.


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