Osteoarthritis (also known as ‘arthritis’ and ‘degenerative joint disease’) is a progressive, degenerative condition of joints resulting in cartilage erosion and inflammation. A common cause of lameness in horses, there is no cure but it can be managed. Articular cartilage has very limited ability to repair so the condition is irreversible. Any joint injury or insult can result in osteoarthritis. Most cases are due to wear and tear. Horses are large animals and put huge forces on their joints. Injuries to ligaments or bone (chip fractures) and inflammation resulting from infection are also causes.
Symptoms of osteoarthritis include:
- Lameness – this may be the only sign in many cases
- Joint swelling
- Pain on flexion of the joint
- Increased lameness after flexion
You should make an appointment to have your horse’s problem investigated by your vet. Lameness examinations are often best performed at an equine hospital to allow a full examination and investigation with appropriate equipment. Lameness investigation is extremely challenging and can be very time consuming.
Your vet will perform a comprehensive lameness examination. Following the examination, nerve blocksare then used to localise the lameness or confirm that a swelling is significant. This can be very time consuming as each block takes at least 30 minutes to fully assess before progressing to the next block.
Once lameness is localised, radiographs are taken to determine the severity and assist with determining a cause. Further imaging may be required, such as ultrasonography, scintigraphy or magnetic resonance imaging (MRI). Ultrasound is used to assess soft tissues and scintigraphy may be needed to assess bone if radiographs are not productive. MRI is available at some specialist clinics and gives very detailed images of soft tissue and bone.
Treatment for your horse will depend on the severity of the symptoms and may include:
- Rest and anti-inflammatories such as phenylbutazone.
- Anti-arthritic drugs, e.g. pentosan, hyaluronate.
- Feed supplements containing glucosamine and/or chondroitin sulphate.
- Intra-articular medications, these include corticosteroids, hyaluronate./li>
- Arthroscopic surgery – removal of chip fractures, trimming of cartilage and synovium, and flushing out of enzymes are all beneficial to the joint.
This statement is based on experiments where cortisone was used at extremely high dose rates in normal joints. More recent studies have shown that lower doses in arthritic joints actually prolongs the life of the cartilage. Used carefully, cortisone can increase the functional life of a joint significantly. There are risks, as with any treatment, so consult your vet about all the pros and cons before agreeing to intra-articular therapy.
It probably isn’t possible to prevent osteoarthritis, especially in horses undergoing heavy athletic work. Measures you can take to help prevent your horse from developing the disease (especially at an early age) include:
- Keeping your horse well shod – well balanced feet will reduce the stress on lower limb joints.
- Avoid work on hard ground – this will reduce concussion to the lower limb joints.
- Use cold therapy (icing) after hard work – this will help control inflammation.
- Regular use of anti-arthritic preparations – this may be helpful, but their cost effectiveness is questionable.