One joint disease that can affect horses as they age is ringbone. The term ringbone is used to describe osteoarthritis, inflammation, and loss of cartilage, in either the pastern joint (high ringbone) or the coffin joint (low ringbone). Once a horse is diagnosed with ringbone it takes a team effort between your veterinarian and farrier to manage it.
When horses are diagnosed with ringbone, it is important to make a distinction between high and low ringbone, as the specific type may affect treatment and the horse’s prognosis. Two more important terms to understand when discussing ringbone are articular ringbone and periarticular (also call non-articular) ringbone. Articular ringbone often affects the entire joint—causing problems with the cartilage and the joint lining (synovium) that make the joint enlarged, painful and stiff.
When a horse has articular ringbone, x-rays show a partial or complete narrowing of the joint space, new bone growing into the joint (called osteophytes), increased density of the bone directly beneath cartilage (called sclerosis), or erosion of the bone beneath cartilage (called lysis).
Periarticular ringbone affects the soft tissues, including the ligaments and tendons, around the joint. Radiographs of horses with periarticular ringbone show bone growth away from the joint. It may occur where the ligaments attach to the bone or joint capsule (called enthesophytes) or anywhere that the connective tissue that covers the bone has been damaged.
What Are the Causes?
Not all older horses get ringbone—and, while not common, ringbone can affect a younger horse. While there is no sure way to determine which horses will develop ringbone, there are several factors that contribute:
- Poor conformation. Overly upright pasterns, angular limb deformities, toeing in and toeing out all lead to increased concussion put on the joints, which can cause ringbone.
- Trauma. Strains and sprains to the soft tissues surrounding the joint also lead to ringbone. This type of trauma is most common with performance horses who routinely make sudden stops and sharp turns, such as polo ponies and reining and cutting horses. Joint infections may also result in ringbone.
- Developmental factors. Osteochondrosis dessicans (OCD) and subchondral cyst-like lesions (bone cysts) also predispose a horse to develop ringbone later in life.
- Long-term concussion and hard work. Performance horses who endure concussion and hard work have a greater tendency to develop ringbone. This includes western performance horses, barrel racers, eventers, racehorses, and jumpers. cont.
- Nutritional imbalances. Horses who suffer poor nutrition, especially early in life, may be more likely to develop ringbone as they age.
- Poor hoof care. A lifetime of improper trimming and shoeing can put unusual pressure on the joints of the horse’s leg, which can lead to ringbone.
Ringbone may initially go undiagnosed. The first sign a horse shows is lameness, and many equine professionals will first lay the horse up to see if it goes away. In the case of ringbone, the rest will make the horse appear sound, but he usually becomes lame again after he goes back to work. So how can you differentiate between general lameness and ringbone? Initially, lameness may be accompanied by two signs that the horse is suffering from ringbone: a warm swelling around the pastern area that goes away with rest, and sensitivity to any pressure put over the pastern joint. As the disease progresses, the warm swelling turns to a firm, cool enlargement of the pastern area, and the horse often becomes progressively lamer.
To definitively diagnose ringbone, the horse needs to see a veterinarian. He will probably ask the owner for a history of the horse’s lameness, watch him move, and feel his legs for swelling. The most accurate diagnosis will come from the use of nerve blocks and radiographs to determine if the horse has ringbone and what type he has (high versus low).
Treatment: Is It the End?
Owners often fear hearing a diagnosis of ringbone because the disease is progressive, meaning the horse’s lameness gradually grows worse. There was a time when most horses with ringbone were eventually euthanized due to pain and lameness. No longer. Dr. Laurie Shelton of Brenham, Texas, sees several horses with ringbone each year and says that treatment has evolved so that euthanasia is not always their fate. She says that while some of the horses she sees are no longer ridable, treatment slows the progression of the disease in others. She even treats some horses with ringbone who are still competitive in their fields.
The proper and timely treatment gives horses the best chance of staying sound. The veterinarian on the case will consider the horse’s soundness, type of ringbone, and its progression when prescribing a treatment. Short-term treatment may include stall or pasture rest, non-steroid anti-inflammatory drugs (NSAIDs), leg wraps, and either hot or cold therapy to control the swelling. Dr. Shelton says that long-term management focuses on pain relief and either slowing down the progression of ringbone or speeding up the progression so that the joint fuses and there is no more pain.
Long-term treatment varies from bute or other painkillers administered orally to injecting corticosteroids into the joints to systemic doses of hyaluronic acid and glucosamine in the form of Legend or Adequan injections or oral Cosequin. Long-term management of horses with ringbone should also include a properly balanced trim for the horses’ hooves. Some veterinarians recommend shoeing with a rolled toe for easier break-over, while some horse owners prefer to use a barefoot approach to managing ringbone (see sidebar). When determining a treatment protocol for a specific horse, Dr. Shelton considers the severity of ringbone, the horse’s response to therapy, and the owner’s finances.
Surgery is also an option for some horses with high ringbone. During surgery, the pastern joint is fused by removing the cartilage between the bones and binding the two bones together with screws. Fusing the joint eliminates pain by rendering the joint immobile, and since the pastern joint normally has limited mobility, surgical fusion has little effect on performance. Unfortunately, the coffin joint requires a lot of mobility, so surgery is not an option for horses with low ringbone.
While ringbone was once an almost certain death sentence for horses, today there are many options: NSAIDs, joint injections, and even surgery. Depending on the type of ringbone, and where it is in its progression, affected horses can continue happy, even productive lives.
Jennifer Williams, PhD