A great challenge facing owners and managers of show and lesson horses is keeping them comfortable and happy in their jobs. High-speed work and jumping is “hard on their joints,” according to Hilary Clayton, BVMS, PhD, MRCVS, Mary Anne McPhail Dressage Chair in Equine Sports Medicine at Michigan State University. The signs may be subtle at first: a shorter stride, reluctance to change leads, refusing jumps, less desire to move forward, or minor heat and swelling. These are classic early symptoms of what may be the number one reason for early retirement of performance horses—arthritis.
The initial contact the hoof makes with the ground is the most important phase of the stride in relation to developing degenerative joint disease (DJD). As the hoof approaches the ground, it is moving forward and down. When it hits, a shock wave is sent up the horse’s leg. While bone and cartilage disperse the shock wave, excessive impacts may lead to microfractures of the bone. The cartilage is present in such a thin layer that it isn’t able to help much. Repeated impacts over the years can lead to irreparable cartilage damage.
It is best to get an accurate diagnosis the moment DJD is suspected, because the earlier treatment is started, the better the chance to halt its progression. Your veterinarian may block different joints in order to determine exactly which is the culprit. Radiographic changes indicate that damage has already been done.
Many vets will use a combination of treatments to help the horse. Horses respond differently to products and treatments; if one treatment doesn’t work, another may, so it could take some time to find the right combination. This also means it is very important to consult your vet as he/she can help you work through all of the options. “It’s very individual,” says Sarah Link, DVM, who has a large-animal mobile practice based in Thurmont, Maryland. She says much depends on what the horse is doing and what the owner wants the horse to do. If the goal is to make the horse more comfortable, she takes a more conservative route. If the horse is to go back into work, the approach becomes more aggressive.
Managing the Problem
While the overall goal is to prevent DJD before it occurs, once arthritis sets in, the goals of treatment are to increase range of motion, decrease pain and inflammation, and slow or stop cartilage degeneration. While rest is good for an acute onset, it can actually make chronic arthritis worse. Light exercise, in the form of turnout or light riding, is good for chronic cases and helps strengthen the soft tissue that surrounds the joints. It is important, however, to work arthritic horses within their capacity. Static stretches help increase range of motion. Clayton suggests letting the horse go barefoot if possible. Using liniment and wrapping the leg may decrease inflammation. Alternative therapies, such as chiropractic and acupuncture, may also help relieve pain, but their effects are only temporary.
The Importance of Your Arena
“Look out for the footing,” warns Clayton. She suggests looking for a footing that is “a little bit resilient.” Pay attention to the impact resistance of the footing, the degree to which it causes shock to the horse’s joints. (Concrete is an example of a footing with high impact resistance; wood chips, of low impact resistance.) Hard ground is very detrimental. Working young horses on hard ground may lead a silent progression toward arthritis later in life. In addition, hard surfaces don’t allow the toe to penetrate, so they are very hard on horses with navicular syndrome. At the other end of the spectrum, deep or dry sand may have a lower impact resistance, but it is more tiring and may lead to other types of injuries. It is important, when managing your horses, to try and avoid abrupt changes in footing, inconsistent surfaces, and to make sure your horses receive the proper training and conditioning for their jobs.
Hyaluronic acid (HA) is a naturally occurring substance produced by the synovial membrane that lubricates joints, cushions cartilage and protects synovial membranes. Horses with arthritis have low levels of HA, so injections directly into the joint help make up for what’s missing.
Corticosteroids are injected into the joint to quickly reduce pain and inflammation. However, Link warns that injecting with corticosteroids “is not a benign thing.” It contributes to breaking down the joint cartilage over time.
The number of injections needed in a year depends on how well the horse responds to them. However, any time you inject a joint, there is a slight risk of infection, and that should be kept under consideration.
Polysulfated Glycosaminoglycans (PSGAGs), are usually made with chondroitin sulfate and typically given via an IM injection. They help increase HA production, improve joint lubrication and help repair cartilage.
Non-steroidal anti-inflammatory drugs (NSAIDs), such as phenylbutazone (Bute), flunixin meglumine (Banamine), ketoprofen and aspirin are the first line of therapy in minor musculoskeletal pain and used frequently in arthritic horses. However, there has been some concern that long-term use of NSAIDs is detrimental to the horse. NSAIDs reduce inflammation, but some inflammation is necessary for the healing process. A study done at Ohio State University found that Bute suppressed bone formation and healing. Oral administration of Bute for 14 days significantly decreased proteoglycan synthesis. Researchers concluded that NSAIDs should be given to arthritic horses only to make them more comfortable, and the lowest effective dose should be given.
However, they do note that there is no evidence that giving a horse Bute for his entire life would cripple him. It is more potent at decreasing inflammation than it is at increasing joint degeneration. Link pointed out that she has had horses on one Bute tablet per day for a long period of time and they did fine and tolerated it well.To avoid ulcers, though, it helps to use it for a short period of time.
Possibly the most visible treatments today are the oral joint supplements. There are many on the market, but their effectiveness is difficult to prove. It is not known how much of the product is absorbed into the horse’s system. However, they are safe and some horses respond to them, so they are often used in support of other treatments.
Caught early and treated well, joint disease does not have to end a horse’s career. Ensuring good working conditions and constant monitoring will reduce the incidence of joint disease and minimize its impacts.