Is Your Horse's Soundness Chipping Away?
- Jul 1, 2002
The old adage, "Something's gotta give," holds true when you accidentally bump a dinner plate on the counter and it chips or you bang your car door on the car next to you and the paint chips. Trauma inflicted upon an object can cause a chip. The same action/reaction principle applies to equine joints--a fact corroborated by equine orthopedic experts who see and treat their fair share of joint chips.
The most widely accepted treatment for chips is arthroscopic surgery, which uses a tiny fiberoptic video camera inserted through an incision roughly one-quarter-inch long. Small surgical instruments then reach the joint through a second small incision. The procedure gives damaged joints new life with minimal surgical trauma.
Joint chips occur most frequently in the carpus (knee) and fetlock (ankle) of racehorses, according to Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, Dipl. ACVS, professor of surgery and director of orthopedic research at Colorado State University and a pioneer in equine arthroscopy.
"A lot of the chip fragments we take out of non-racehorses have a developmental pathogenesis," he says. "For example, in warmbloods, it may arise due to osteochondrosis dissecans (commonly referred to as OCD)."
"Most chips are associated with cyclic (repeated) trauma and not an acute event, and are secondary to bone disease," says McIlwraith. "We're talking a pathologic fracture, one in a bone already diseased. When a horse gets miles on him, the chips can be exacerbated by conformation or inherited effects, and the horse develops microfractures and microdamage in the bone, which eventually can coalesce and allow a fracture. They can occur in the front of the knee at the edge of the articular surface or at the front of the fetlock or P1, the first phalanx."
Greg Beroza, DVM, Dipl. ACVS, Dipl. ABVP, of the Long Island Equine Medical Center and another highly experienced arthroscopic surgeon, agrees that pathology of the joints is a degenerative process that gradually and naturally occurs in all of us, human and equine alike.
"In performance horses, however, those changes that are arthritic in nature occur more quickly up until the point that some horses develop chips," he explains. "A section of the joint surface actually breaks off; if large enough, it can be screwed back into position surgically.
"Some chips are as small as a grain of sand; others are the size of a thumbnail or toenail," Beroza continues. "The smaller the piece, the less likely it is to be of structural benefit and therefore the better choice is to get rid of it. If the anatomy or circumstances are amenable to fixation, with surgery we can stabilize them back where they came from."
Clinical Signs of Joint Chips
The signs of joint chips, according to Alan Ruggles, DVM, Dipl. ACVS, of Rood and Riddle Equine Hospital in Lexington, Ky., are lameness, swelling, and poor performance. He sees diverse cases of bone cartilage fragments either from fractures or resulting from OCD.
Ruggles presents the following examples: "I might see a young horse with joint swelling in the hock, perhaps a warmblood with a piece of bone cartilage off the tibia in that joint caused by OCD. And you could have the same breed of horse develop acute swelling from chipping a bone or piece of cartilage off. The cause of one is the failure of cartilage to form normal bone, as in OCD; the other is from trauma."
For Ruggles, as for his veterinary counterparts, "There are three ways to manage these conditions--ignore, inject, or intervene with surgery."
Ignoring might not be so unreasonable, proposes Ruggles-- "if the chips are found as incidental, as in a pre-purchase exam in which the horse has never been lame and exhibits no other signs. The key is whether the piece might ultimately cause degeneration of the joint, or whether its presence will cause lameness or reduce performance. It really depends on those clinical signs, the intended use of the horse, whether there is the potential for resale, and the cause."
If surgery is too expensive for that owner, Ruggles might choose injection, and he will use one of the hyaluronic acid (a lubricant for the synovial membrane) products. He cautions against using cortisone in the presence of joint fragments: "Data shows that can cause degeneration."
Client attitude plays a predominant role in determining the appropriate treatment, acknowledges Ruggles. "A subset of my clients might say, 'Don't worry about it,' or 'I'll worry about it later.' If the horse is potentially for purchase, you don't want to cause questions in the buyers' minds: When you sell a horse, remove as many questions as you can."
McIlwraith counsels, "Whether you can get away with injecting and conservative therapy depends upon the location of the chip. Injecting joints can promote secondary osteoarthritis. These secondary changes in the joint will occur with some sites being more prone than others.
"Let's say there's a chip located off the distal radial carpal bone (lower inside bone in the knee)," McIlwraith continues. "I consider it absolutely necessary to do surgery right now in these cases, for if you continue training the horse, you'll cause severe damage to the joint. On the other hand, in some locations, particularly in the upper joint of the knee, you can get away with quite a bit, because that joint is more forgiving."
McIlwraith will inject steroids in combination with hyaluronic acid: "Hyaluronic acid alone often won't provide enough anti-inflammatory action," he says. "With a chip, the secondary inflammation in the synovial membrane causes most of the compromise."
Conformation Builds a Horse
The role of conformation in joint chips is the subject of some controversy within the equine veterinary community.
Says Beroza, "It seems more likely that conformation is an element that we take into consideration; horses with more perfect conformation seem less likely to have joint chips. For example, if you're building a building, you want every floor to be as square as you can make it, or the danger will become cumulative and you'll eventually have problems."
Beroza, like his colleagues, doesn't worry so much about the horse's age, but rather the degree of use of the horse, i.e., his training level or exertion. Chip prevalence might be related to conditioning of the animals, "which many trainers don't want to hear. Horses that are better conditioned are less likely to develop chips--the same applies to people."
Beroza believes that, as in many aspects of life in general, owners and trainers "need to seek a balance. Of course, conditioning is very important for the trainer, but too much exercise in too short a period and you can overtrain the horse, which results in soreness from working so hard. As we know, trainers are under time constraints and time is money. However, the body doesn't always work that way."
Beroza treats mostly joint chips in the knees and fetlocks of horses, but also sees some occurrences in hocks or stifles.
"Genetics may play a part," he adds, "and some family lines of horses may be more prone to arthritic injuries, although no one's ever proven that. You may have heard the expression, 'He comes from a family with soft bone.' The problem may be more due to the individual horse's conformation rather than strictly genetics."
The majority of Thoroughbred race injuries Beroza sees are a result of overextension of the knee, or "back at the knee" conformation, which puts more pressure on the front of the joint. Overextending the fetlock also puts pressure on the front of the ankle joint.
"Most hyperextension injuries might be minimized through better conditioning so that the muscles around the knee are made tighter," says Beroza.
"It only makes sense, since toward the end of a race when the horse is fatigued and being asked for more speed and power by the jockey, the horse is also at his weakest," Beroza adds.
Racehorses aren't alone in their propensity to chips; specific arthritic conditions and injuries can be unique to different breeds of horses and different athletic uses. Their discipline can make them prone to various types of injuries, not only joint chips, but also OCD.
"Hitting fences or landing extremely hard may cause joint chips," says Beroza. "Dressage horses may develop them, too. Warmbloods are a little more prone because they're later-maturing horses; they seem to have more problems with developmental diseases rather than chips. Even Standardbreds can be prone to developmental diseases; when they're young, we can discover little chips in the hocks."
"Some barrel racers get fragments," comments McIlwraith, "as relics from their racing days. Others can occur with barrel racing."
All Chips Aren't Created Equal
Experts agree on surgery in most cases--and sooner, rather than later. The cost of arthroscopic surgery varies widely, depending upon the veterinarian performing the surgery and his geographic location. Expect to pay between $1,500 and $4,000.
"If it's a fresh chip," says Beroza, "it probably makes sense to take it out. Think of it like this: You have a small pebble in your shoe, and you stop while you're walking to get it out, versus continuing to walk. If you eliminate the potential problem early, you could prevent a blister or callus later."
McIlwraith concurs that most often, "The ideal treatment is arthroscopic removal of the chip, especially if it's causing clinical signs, which can be quite subtle. We have data showing that if you remove the chip and any surrounding damage before secondary arthritic cartilage degeneration or osteoarthritis can occur, the prognosis is usually excellent.
"If you wait until later, and secondary changes develop, the prognosis can be poorer," McIlwraith adds.
Beroza remembers "the old days, when we had to open up the joint and look, then clean it out, leaving a large soft tissue scar. When we began using arthroscopy, it brought all new equipment and a new way of looking at surgery--wounds were less obvious and recovery was quicker."
When he is contemplating surgical intervention, Beroza prefers "a fresh fracture without any arthritic changes, or a joint that's not been previously medicated. Realistically, many joints have been previously medicated, and we are concerned there can be a greater incidence of infection and arthritic changes after surgery. Fortunately, with arthroscopy, the chances of these complications are fewer than with the previous standard open joint surgery. The fewer changes, and the fewer times a horse has had surgery, make the scenario a greater opportunity for success."
Suppose an owner brings a horse to the clinic for an ongoing undiagnosed lameness, and a chip is found? Beroza says, "Sometimes an owner falsely believes we can take the chip out when the horse also has advanced arthritic changes, and that it will be helpful. But we can't reverse those (arthritic) changes that have already occurred. If we simply remove the chip, we may not see dramatic improvement. The horse may not get much better, but he also may not get a whole lot worse. Early intervention is the key."
Ruggles reports a high arthroscopic surgery success rate in his practice. "A high percentage of horses return to athletic function or can pursue athletic endeavors. In young horses with OCD, there is usually a very high return to complete recovery and the ability to potentially do what they're supposed to do--the prognosis for athletic function is good to excellent. Early treatment leads to a very high outcome.
"In older horses of two or three years, the determining factor in removing a chip is dependent upon what additional cartilage injury is present," he continues. "If there is damage in the joint, it's a good reason to remove the chip.
"All chips aren't created equal," says Ruggles. "OCD can occur anywhere cartilage forms bone, not just in hocks, stifles, or fetlocks--which are the most common sites--but even in the neck."
Ruggles warns, "You don't know until you scope the horse; you could have a chip on the radiograph, then see telltale signs of degenerative joint disease (during arthroscopic examination)."
After surgery, lay-up time for the horse can vary, but in general, expect from six weeks to six months depending upon secondary damage.
McIlwraith says for his patients, if the surgery was fairly "simple," six to eight weeks is common. In cases of severe secondary involvement, six months might be indicated. "Most of my cases average out to between two to four months," he says.
Beroza also anticipates a two- to four-month rest period following surgery. "I don't like a quick return to full use, even though trainers sometimes succeed in pushing that issue."
For the owner who's "on the fence" concerning treatment options, Beroza asks, "At what point is the chip doing more damage, advancing the pathology more quickly? The best thing you can do is find the best veterinarian to give you the best opinion, then use it wisely."
Like New Tires on a Car
Eclipse Award-winning trainer Bob Baffert, who's based at Santa Anita Park in southern California, is a fan of arthroscopic surgery, since he successfully utilized it on approximately 50 of his top campaigners, including 2001 third-place Derby finisher Congaree. Baffert reports that Congaree is doing great, with earnings of a million dollars.
"Used to be," remembers Baffert, "with a knee chip, you had to open the whole knee up, and half the time the surgery didn't work. Now, with arthroscopic surgery, it's almost as good as putting new tires on a car. It's really changed a lot.
"If the chip is aggravating the horse, if they can't work through it and you don't remove it, it can hurt the other leg, too (through overcompensation for soreness)," he continues. "It usually works well on lots of horses; it saves the careers of a lot of horses."
Whether your horse is a winner on the track or in the hearts of your family, current medical advances mean that joint chips aren't always the threat they used to be. A thorough consultation with your veterinarian to discuss options is the first step to making your horse more comfortable physically, and to putting your mind at ease.
About the Author
Stephanie Stephens is a USEF Media Award winner and American Horse Publications award winner whose work appears in major consumer magazines worldwide. She lives in Southern Calif., but she splits her time between New Zealand and the United States.
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