Degenerative Joint Disease (DJD) in horses

Degenerative Joint Disease (DJD), a chronic form of osteoarthritis, is a disease that affects the horse and its movement patterns in a negative way. Karl-Henrik Heimdahl, equine veterinarian at Agria Djurförsäkring, explains the concepts surrounding it and some common myths.

What is DJD?

DJD breaks down the articular cartilage in the horse's gliding joints, often causing it to experience pain and show lameness. If a horse has bone spurs, it means that it has a chronic inflammation in the gliding joints of the hock, something that can cause deposits.

“[DJD] is a difficult disease to assess in such a way that there is no connection between X-ray changes and pain; there are horses with little changes that are in a lot of pain, and there are horses with a lot of changes that are barely lame. It is very individual how spat affects the horse and each treatment plan is unique.”

Karl-Henrik Heimdahl

Agria Djurförsäkring / Veterinarian

Why do horses get DJD?

It is unclear why some horses get DJD and it can occur for various reasons. An injury can lead to the horse starting to load the hock differently, which causes inflammation in the joint. Another reason could be that an incorrect hind leg position causes the horse to load the hock more or incorrectly. The overload leads to joint inflammation which eventually causes deposits, i.e. osteoarthritis, in the gliding joints of the hock. Another theory is that it is genetic.

Symptoms of DJD

One of the first symptoms of DJD may be your horse showing reluctance to work and to submit, but the symptoms are often subtle at first. Some horses drag their toe a little or are more stiff at the beginning of the riding session. At a later stage, the horse usually becomes lame on one or both hind legs, but there are also horses that show no lameness at all.

Investigation

If DJD is suspected, the veterinarian performs a clinical examination of a horse and looks at joints, tendons and ligaments. A flexion test is performed, where horses with DJD usually show greater lameness after the flexion test of the hock joint. It is also common for the vet to choose to x-ray a horse before establishing that the diagnosis is DJD. An anaesthetic of the horse's gliding joints is used to ensure the diagnosis.

Forecast

Although DJD can be a serious disease that has a major impact on horses, the prognosis depends on which joints, and how many, are affected. Some horses are not particularly affected by DJD and can be ridden more or less as usual, while others cannot be exposed to any type of work.

Treatment and rehabilitation

A common treatment is to allow the breakdown of cartilage between the small bones in the gliding joints to continue until the cartilage is gone and the bones "grow together". Then the inflammation usually disappears and thus the pain. The horse is put on anti-inflammatory medication and light exercise is prescribed - something that speeds up healing.

Without exercise, the inflammation can remain at a lower level for a longer period of time. The horse does not get better or worse, but becomes lame when it is put to work again.

“Rehabilitation can take a long time, from a few months to several years. In the meantime, regular contact with the veterinarian is necessary to evaluate how the spat develops and affects the horse, and to adjust the treatment plan. Unfortunately, there are many horses that do not turn out well, while others can function as walking horses.”

Karl-Henrik Heimdahl

Agria Djurförsäkring / Veterinarian

Healed DJD

Sometimes you hear the expression "healed DJD". This means that the joint is fused and that the inflammation has stopped. These horses are usually completely symptom-free.

“But there is no guarantee that the horse will remain symptom-free in the future. Sometimes these horses' "healed [DJD]" can also be activated and cause new lameness symptoms. The vast majority of horses with [DJD] have reduced performance and require adapted work.”

Karl-Henrik Heimdahl

Agria Djurförsäkring / Veterinarian

Is DJD hereditary?

It has long been researched and discussed whether DJD is hereditary and whether it is suitable to breed mares with DJD.

“What the research has shown so far is that inflammation and osteoarthritis are not hereditary. However, an incorrect leg position or a movement pattern that puts excessive strain on the joint can be inherited. If you have a mare with correct leg position and normal movement pattern, which has worked and performed well for several years, the spat diagnosis is probably not due to hereditary factors”

Karl-Henrik Heimdahl

Agria Djurförsäkring / Veterinarian

Research on early detection of DJD

In a research project at SLU, the hock joints of a number of Icelandic horses - a breed where DJD is more common than in other breeds - have been examined using a magnetic camera, x-rays and various microscopic examinations. It was established that it is possible to detect early stages of DJD, even before the horse shows lameness, with the help of ordinary x-rays. This is because horses that are about to develop DJD often have a small defect in the articular cartilage.