Just like humans, older horses may show stiffness in their gaits; very often this is caused by arthritis. Arthritis is almost unavoidable as a horse ages, but early diagnosis and conscientious care can slow its advance and minimize pain.
What Is Arthritis?
Osteoarthritis is a degenerative joint disease (DJD) involving the breakdown and loss of the cushioning cartilage that lines the end of bones within a joint. With this breakdown there is also loss of lubricating joint fluid and the joint as a whole loses its ability to cushion impact and provide a gliding surface during motion. This then results in joint pain and leads to lameness in horses. Arthritis in specific locations in horses goes by common colloquial names such as ringbone and bone spavin.
Symptoms of Arthritis in Horses
In its early stages, arthritis may appear as a slight stiffness that the horse works out of once it is warmed up. In the joint, the cartilage material is breaking down but not repairing itself efficiently. Eventually, as the cartilage becomes more damaged, the bone beneath the pad of cartilage becomes damaged as well. The horse will then experience more discomfort and there may be heat in the joint as inflammation occurs. In more advanced cases, small bony growths called osteophytes may be seen under X-ray and may be felt around the affected joint. As the disease progresses, the horse may experience more discomfort and lameness.
Causes of Arthritis
Arthritis is caused by the wear and tear of cartilage—the tough, flexible tissue that is the shock-absorbing and sliding surface between the bones that meet at a joint. Over time, compression and stress wear away the protective cartilage. Arthritis most commonly occurs in the weight-bearing joints of the legs. Extra stress or injury to any joint can lead to arthritis.
Specific sports can make a horse more susceptible to arthritis in certain joints due to repetitive concussive force. Certain types of conformation in a horse can also make it more susceptible to the development of arthritis. However, as all horses age, as with humans and other animals, repetitive wear and tear causes damage of varying degrees to high motion and weight-bearing joints.
Equine arthritis can affect any mobile joint in the body, including the knees, shoulder joints, spine, fetlocks, hocks, and stifles. The fetlocks, knees, coffin bone (within the hoof), and hocks are most commonly affected. These are all weight-bearing joints.
The goal of arthritis management is to reduce the inflammation in the affected joint, relieve pain, and slow further damage to the joint. There is no treatment or cure for arthritis.
If you notice that your horse is having any discomfort (even discomfort that wears off quickly), it's a good idea to consult your vet. Your vet may be able to identify arthritis early and slow its progress with drugs that reduce inflammation.
Once the cartilage in a joint is damaged or gone, it is difficult to repair it. Discomfort can be managed by joint injections of joint fluid supplements like hyaluronic acid and polysulfated glycoaminoglycans as well as corticosteroids. Oral non-steroidal anti-inflammatory (NSAID) drugs such as phenylbutazone can also be used for pain management, but long term use can have negative side effects such as gastric ulcers and the potential for kidney damage. For longer-term treatment, newer medications include firocoxib (an NSAID that works differently than phenylbutazone) and diclofenac sodium, available in a topical cream. Various stem cell therapies are being explored by some clinicians. In some cases, depending on the horse and what joints are involved, this modality may also be an option. Shockwave and laser therapies may also be considered.
In addition to veterinary treatment, a reduction in workload may be necessary, especially if the work includes jumping, traveling over hard terrain, or other activity that potentially over-stresses the joints. This may mean the end of a horse's competitive career, although light exercise is important to maintain joint flexibility. At times when the horse may be lame, it should not be ridden. Keep the horse on soft footing, with extra, but not excessive bedding that may be hard to walk through. Proper trims and shoeing by a knowledgeable farrier may also be helpful.
How to Prevent Arthritis
Arthritis, to some degree, is almost unavoidable in older horses. Horses with conformation faults may put extra stress on joints, yet another reason why breeders strive for foals with good conformation. Proper hoof trims and shoeing, good conformation, providing good footing, while also providing good basic maintenance, can also help to delay the onset of arthritis.
Joint Disorders In Horses. Veterinary Manual, 2020
Management of Osteoarthritis in the Equine Athlete. University of Illinois College of Veterinary Medicine, 2020
Treatment of Equine Osteoarthritis: The New Frontier. University of Illinois College of Veterinary Medicine, 2020