Degenerative joint disease (DJD) is another name for osteoarthritis, which is the most common type of arthritis in horses. It is a chronic, (i.e. long-standing) disease in which the cartilage on the ends of bones wears down, resulting in loss of joint mobility, swelling, heat and pain.
It is a common cause of lameness, reduced performance or stiffness, especially among older horses, that often improves with gentle exercise. It can affect a single joint or several joints simultaneously. It was the second highest source of insurance claims during 2018 according to Petplan Equine¹. In more severe cases it is a common cause for retirement of an older horse.
Bone spavin (arthritis of the lower hock joints) and ringbone (arthritis of the pastern or coffin joints) are two of the best-known examples, but any joints are at risk.
The causes of DJD are not clear and currently the condition cannot be prevented. Once established, it can only be managed, not cured. Management must aim to reduce pain and minimise progression of the condition by stimulating the cartilage and inhibiting further degradation.
Another serious type of arthritis found in horses is septic arthritis. This is an acute form of DJD caused by a bacterial infection inside a joint. It is typically seen in foals that have compromised immune systems or systemic disease, as well as in horses of any age that have suffered a traumatic injury near a joint. In all such cases, infection enters the joint cavity, which can be difficult to treat. Unless a septic joint is treated rapidly and aggressively, usually by flushing out the contamination, it can be career-ending.
Signs of DJD
Typical signs of DJD include:
- Horse demonstrates stiffness that gradually reduces with gentle work
- Swelling of one or more joints in the leg; commonly the lower limb, such as the fetlock, pastern joints, knee and/or hock
Treatment of DJD
Most arthritic conditions of ‘high motion’ joints (such as the fetlock) cope well if you can maintain active movement through low impact exercise, in addition to reducing the load and internal inflammation within the joint.
This can be achieved via a treatment plan focusing on both:
- Physical management — such as changes in diet, exercise, shoeing, stable/environment
- Pharmacological management — the use of drugs
As long as lameness does not increase, it is best to keep the horse active. Spend extra time warming up and avoid working the horse on hard, concussive surfaces at any pace faster than the walk.
It is important to keep the horse’s weight under control as excess weight can cause more pressure on the joints.
Talk to your vet and farrier to ensure there is a good hoof-pastern axis in order to equalise the weight distribution throughout the lower limb.
Monitor the progress of the condition and make changes to the levels of exercise as appropriate.
Oral non-steroidal anti-inflammatories — the use of oral pain killers/anti-inflammatories is common in the management of this chronic condition. A good way to help an arthritic horse is to use bute strategically — if you only ride once a week, then give bute the day before the horse is worked and the day after. By doing this you gain the maximum benefit without the body becoming used to the medication.
Steroids — There are several types of steroid available to inject into joints to reduce the ongoing inflammation, with different medication being required for different high and low motion joints. The individual advantages/disadvantages of each these need to be discussed with your vet. There are other newer options for intra-articular (i.e. into the joint) therapy, such as products derived from stem cells, see autologous products below.
Polysulphated Glycosaminoglycans — these products with the principle component chrondroitin sulphate can help to prevent cartilage degeneration.
Pentosan Polysulphate — these products have been suggested to help stimulate hyaluronic acid production within joints, which is essential for good joint function. These products include Cartrophen.
Bisphosphonates — these products are designed to affect the “turn over” of bone, which can be excessive during the arthritic process. Once again, these products have many advantages and disadvantages, which need to be individually discussed and evaluated with your vet.
Autologous products — these are products derived from the patient, quite often by extracting blood/bone marrow or fat and processing it prior to re-implantation back into the patient. This is a very specialised therapeutic avenue, but has very promising results.
Many of these treatment options are not permitted in competing racehorse and/or sports horses.
There is a range of alternative therapies that have some anecdotal evidence for use helping horses with DJD. However, very few, if any, have peer-reviewed, double-blinded studies demonstrating their effectiveness. That is not to say that they do not work, but vets require all treatments to have some form of proven safety record or, at least, should have peer-reviewed critiques of the product used.
This lack of research means few vets will recommend the use of alternative therapies to help manage DJD. However if you wish to try alternative therapies on your horse, those with anecdotal evidence to support their use include:
- Magnetic boots
- Nutritional supplements
Under Veterinary Medicines Directorate (VMD) rules, nutritional supplements cannot claim to treat an established medical condition, but there are numerous joint supplements available that have been formulated purporting to help support joint health. They vary in their ingredients, with many containing chondroitin sulphate and glucosamine, others glucosamine alone, or a mixture of plants and herbs including meadowsweet, nettle and yucca, with devil’s claw.
As with any degenerative disease, the prognosis is guarded, but in most cases a horse with DJD can be managed with a suitable exercise program, supported by appropriate medications.
The management of any degenerative condition is multifactorial and should be tailored to every individual patient with your vet, farrier, physiotherapist, nutritionist and trainer as it will vary greatly depending on the age of the horse and the work he is doing.
1: Top five veterinary conditions – what are they and how can we avoid them? *Promotion*