Time was, a diagnosis of “ringbone” would have been very bad news for a horse---at best, he might be retired to spend his days on pasture. At worst, well, there’s only one humane thing to do when a horse can no longer stand or move without severe pain.
Fortunately, today there are many more options to help a horse who develops ringbone. In fact, if a developing case is identified early enough---and addressed with the teamwork of a veterinarian and a farrier---a horse may stay sound for years to come.
Practically any horse who works hard for a lifetime is a candidate for ringbone. Nonetheless, taking some basic precautions and keeping an eye out for the first signs of trouble can go a long way toward helping a horse remain sound. Here’s what you need to know.
High and low ringbone
“Ringbone” is the term for the bony overgrowth (exostosis) that develops on or around the pastern bones in the wake of injury and/or inflammation. The overgrowth can be articular--- affecting the joint---or develop on the side of a pastern bone, often where the ligaments attach. In some cases, the bony overgrowths may encircle the pastern, hence the name.
If only bone but not joint is affected, ringbone may be little more than a blemish that requires no special treatment. “The bony growth or calcification deposit may grow and expand, but if it isn’t causing pain/lameness, it’s not as much concern,” says Todd Allen, CJF, a farrier in Vandergrift, Pennsylvania.
When ringbone affects the pastern or coffin joint, however, chronic lameness may result. Two types of exostosis can affect the pastern joint: low and high ringbone. Low ringbone develops around the joint between the coffin bone and the short pastern bone, just within the top of the hoof wall.
“Osteoarthritis in the coffin joint can be very problematic because of this joint’s higher range of motion,” says Troy Herthel, DVM, DACVS, of Alamo Pintado Equine Medical Center in Los Olivos, California. Low ringbone tends to be very painful because any swelling or enlargement has little room to expand under the hoof wall, which adds pressure to the joint.
High ringbone develops around the joint between the short pastern bone and the long pastern bone. “High ringbone is more common. The pastern is a low-motion joint but it takes a substantial load---carrying the weight of the horse at each stride,” says Herthel. “It’s an unforgiving joint; once it suffers trauma or cartilage damage it keeps degenerating.”
As with other types of arthritis, ringbone develops when stresses on joints, tendons and ligaments trigger inflammation that cascades out of control, causing further damage rather than healing local tissues. “If the tendons and ligaments that support those joints are put under too much tension, the body responds by laying down some more bone to try to help stabilize the joint,” says Paul Goodness, CJF, chief of farrier services at Virginia Tech’s Equine Medical Center in Leesburg, Virginia. “Then the extra bone gets in the way of movement and becomes problematic.”
Dealing with articular ringbone can be frustrating. “Horses can become very lame, and it’s not always easy to resolve,” says Larry Galuppo, DVM, of the University of California–Davis. “The pastern joint is challenging to treat in horses because it relies a lot on the surrounding ligaments for support and stability. When the degeneration process starts, it can proceed quite rapidly. It may only take a couple of years for serious degeneration resulting in chronic pain.”
Left unchecked, the bony overgrowth may eventually immobilize the joint--- cementing the two adjacent bones together into one solid structure. “This is called ankylosis, and some horses who have it do surprisingly well. The horse’s gait may change but he is not uncomfortable---fusion eliminates the source of friction and irritation,” says Herthel. “But this process can take a long time and most horses would have some degree of observable lameness.”
A tricky diagnosis
The distinctive raised bumps and ridges of ringbone are hard to miss. But by the time the bony growths are evident, the case is already fairly advanced. “It takes a while before you’d see any outward signs such as thickening around the pastern from new bone growth,” says Galuppo. “By the time you see that, the arthritis has progressed pretty far.”
A better approach would be to identify the problem in its earliest stages, when the horse is just starting to become sore, before bony changes begin to develop. But locating the joint or joints that are the source of mild lameness can be difficult.
“Pinpointing the source may entail palpation and flexion of the limb, along with potential regional nerve or intra-articular blocks,” says Herthel. “Usually radiographs of that area are adequate to confirm the diagnosis, though if the injury is acute [before arthritic changes have occurred], the veterinarian may need to do other diagnostics such as ultrasound, a bone scan, CT or an MRI examination to confirm the diagnosis.”
The earlier joint soreness is identified and treated, the better the chances that a horse’s long-term soundness can be preserved or extended. So it’s a good idea to have your veterinarian examine your horse as soon as you notice even minor lameness. “Once you know exactly what you are dealing with, you can come up with the best therapy for that particular horse,” Galuppo says.
How a farrier can help
When a horse is developing soreness in his pasterns, one of the most important first steps is to adjust his trimming and shoeing, if necessary, to minimize the stresses placed on the joints. Your veterinarian and far- rier may need to work together to address your horse’s case both medically and mechanically.
“The mechanics of early treatment involve trying to provide the best shoeing possible,” Galuppo says. “That in itself can be a challenge because there is no one best way to deal with this, no specific type of shoe that works best for all cases and conformations; the veterinarian and farrier must address these challenges on a case-by-case basis.”
When planning a strategy, says Goodness, “We approach this with short-term and long-term goals. The short-term goals are trying to bring the hoof back to as near normal conformation and function as possible. As is often the case, those legs diagnosed with ringbone more often than not also have less-than-ideal hoof conformation. Over the longer term, we must decide how to maintain that ‘as normal as possible’ hoof conformation to enable the foot to function at its best, and what we can to do to help reduce pain.”
One objective is to ease the breakover forces that act on the hoof each time it leaves the ground. “We move the breakover point back, making it as easy as possible for that horse,” says Allen. “Right before the horse breaks over, that’s when those joints have the most pressure, so I want that foot off the ground quicker.”
Your farrier may also suggest supporting the foot at the heel. “The bones descend as the foot loads, and I think there’s sometimes a little pinching as the bones press together in the load phase of the stride,” explains Allen. “You can use a bar shoe or an open heel shoe with pour pads. We use a pour pad on a lot of horses, and that keeps them on top of the ground. Though a lot depends on what the veterinarian recommends. The secret is moderation and not overdoing it---just using a little modification.”
Goodness sometimes recommends synthetic shoes. “Plastic shoes can be beveled to adjust the breakover area, and the material itself helps reduce concussion, which helps reduce pain,” he says. “In my practice I have been using synthetic shoes more and more, especially when the ground is hard and dry. The extra flexibility is a help. I started using these shoes in arthritic situations and had such good results that I am now using them more and more on sport horses in hopes of helping prevent some of these problems.”
Allen says he’s known many horses with ringbone who improved dramatically after just a couple of shoeings. “One horse was so lame he could hardly walk, but after we started working on him he was getting much better,” he says. “We felt good about that, because the owner was considering euthanizing that horse; we feel we accomplished a lot with that one.”
Medication and supplements
Ringbone, like other forms of arthritis, is a progressive disease. Once the process is underway, there is no cure. The goal is to slow its advancement and to keep the horse comfortable as long as possible. Fortunately, a number of therapies can help:
• Nutraceuticals. Many horses with ringbone benefit from feed supplements formulated to support joint health. Common ingredients include glucosamine0, chondroitin0 sulfate, MSM (methylsulfonylmethane), avocado soybean unsaponifiables (ASU) and hyaluronan0, along with other substances. Although these supplements are regulated as food rather than medication, research suggests that they contain ingredients that reduce inflammation, relieve pain and support the growth of healthy cartilage. For that reason, these products are often given as a preventive to help working horses recover from exertion and remain sound even if they have shown no signs of arthritis.
“Omega-3s, glucosamine, MSM, ASU and hyaluronic acid may give benefit to a certain degree, though once the joint is damaged or arthritis has set in, these cases are much more difficult to manage with nutraceuticals or medications alone,” says Herthel.
• Anti-inflammatory drugs. A variety of medications can reduce inflammation and relieve the pain associated with arthritis. “The most common medications used to try to reduce the pain and inflammation associated with ringbone are the nonsteroidal anti-inflammatory drugs, such as phenylbutazone [“bute”] or firocoxib [Equioxx], which a veterinarian can prescribe” says Herthel.
• Joint injections. Certain medications may be injected directly into the joint capsule, for a more targeted effect. Corticosteroid injections have a potent anti-inflammatory action that also relieves the horse’s pain; the downside is that some of these drugs may have adverse side effects, including degeneration of the articular cartilage in the affected joint and an increase in the risk of laminitis. Hyaluronic acid and PSGAGs (polysulfated glycosaminoglycans) are also used for their anti-inflammatory effects and their ability to protect the cartilage.
“Another new treatment modality gaining popularity is injection of a long-acting polyacrylamide hydrogel into the joint, which acts as a synthetic lubricant,” says Herthel. “This pro-duct, used predominantly in Europe and in the process of gaining FDA clearance in the United States, has shown benefits in horses with osteoarthritis of the coffin and pastern joints.” Two products are available in other countries, with trade names Arthramid Vet and Noltrex Vet.
• Bone remodeling medications. Two relatively new drugs, Osphos and Tildren, are sometimes used in horses with ringbone. Both are bisphosphonates, which bind to calcium and inhibit bone resorption, to help prevent deterioration of healthy bone. Both are labeled for use against navicular syndrome, but veterinarians may prescribe them for other bone-related disorders. Osphos is administered via an intramuscular injection. Tildren is given intravenously.
“Originally [these drugs] were meant for treating navicular problems and bone remodeling, but there are many other things they can do,” says Allen. “If a client has a horse with ringbone, I tell them they should consult with their veterinarian and ask about these products. They doesn’t work for every horse, but some horses are helped tremendously,”
• Biologics. These are treatments using agents drawn from living sources, often the horse himself. Two---IRAP (interleukin-1 receptor antagonist protein) and PRP (platelet rich plasma)--- are derived from the patient’s own blood, which is processed to amplify different anti-inflammatory, healing components and injected back into the joint. “IRAP and PRP have a lot of potential for treating ringbone,” Galuppo says.
“There is also a newer product called Pro-Stride which I think has a lot of potential, because it is a combination of IRAP and PRP,” Galuppo says. “There have been some research studies on this new product at Ohio State University by Alicia Bertone, DVM, PhD. So far, this biologic is proving to be a really good product and it may give us a chance to more effectively treat some of these cases early on.”
Another biological treatment, stem-cell therapy involves harvesting undifferentiated stem cells, often from the horse’s own body, and injecting them back into the affected joint to help repair ligaments, joint capsule and perhaps even some minor cartilage lesions.
When a horse with high ringbone is beyond the point where medication, farriery care and other interventions can keep him comfortable, surgery to fuse the joint---called “arthrodesis”---is the next option. “As arthritis progresses and results in joint collapse, we have to fuse the joint to take away the pain,” says Galuppo. “If we can get rid of the arthritic pain, those horses do much better.”
There are several techniques, says Herthel, but “the most common, and current ‘gold standard,’ is to use a bone plate and screw combination using a locking plate system. At our hospital, pastern joints are the most common type of bone-plating procedure we do.”
First any remaining cartilage is scraped away, then the exposed bone surfaces connected using a plate anchored on each. As the site heals---a process that can take six months to a year---the two bones eventually grow together, forming a single, solid structure. Once there is no more friction and inflammation to irritate the joint, the pain eases and the horse can stand and move comfortably.
Even with an altered gait, many horses return to some form of work after a joint fusion. “A horse that just has to travel along a trail has a much higher chance of getting back to work than a horse doing strenuous athletic work,” says Galuppo. “When we do a fusion of the pastern joint in the front leg, we’re looking at about a 50-50 chance to go back to full performance. For a hind leg it may be more like a 60 to 80 percent chance of full recovery and going back to work. We’ve had some horses do phenomenal things after a fusion---going back to jumping, for example, but that’s been more in the hind legs.”
Still, the outcome for a specific horse can be hard to predict. “Some that we think would do great don’t respond as well as we’d hoped, and others that we had less hope for will surprise us,” Herthel says.
Fusion can also be accomplished chemically via the injection of caustic substances into the joint to accelerate the deterioration of the cartilage and the fusion of the exposed bone surfaces. This treatment is considered less invasive and tends to be less expensive, but the outcomes may not be as good, and there is a risk that the injected substances may irritate other local tissues. “Some people have been injecting pastern joints with alcohol, trying to get them to fuse,” says Galuppo. “The literature reports reasonable success, but I have not seen that much success within our practice. It would not be my first choice of treatment for a fusion.”
Finally, fusion isn’t often recommended for low ringbone, which involves the coffin joint. “Fusion for low ringbone is rarely done---and that is mainly a salvage procedure,” explains Herthel. “There are surgical techniques to fuse the coffin joint, but these horses are not going to return to an athletic career. These efforts are simply aimed at making the horse more comfortable for pasture soundness or for breeding.”
Managing a horse with ringbone can strain your emotions. Just like a person with arthritis, he’ll have good and bad days. Nonetheless, with all of the treatment options now available, your horse has a better chance than ever to remain healthy and sound for years to come. “We can do more today with early intervention than in previous years, and we can make shoeing adjust- ments that can help sport horses stay sound,” Goodness says. “Ringbone is a degenerative process; we can’t really stop it, but with good teamwork ---the veterinarian, farrier and owner working together---we can often slow it down considerably.”
This article was originally published in EQUUS 485, February 2018