Leg Injury Rehabilitation
When your veterinarian informs you that your 6-year-old gelding has sustained a suspensory ligament injury in his left foreleg, your heart sinks. Not only are you concerned about the amount of pain and suffering your horse will endure in the months to come, but you are also concerned about other conditions that could develop as a result of this injury.
One of the biggest fears of horse owners is a leg injury that ends the horse's career, or sometimes threatens his life. However, while some injuries might be too severe to allow for a full recovery, today it is possible to rehabilitate many of the more common leg injuries. Many rehabilitated horses live long, comfortable lives, and a significant number are able to return to the same level of work.
Common Leg Injuries
"Depending on what they do for a living, horses are going to be predisposed to certain injuries," notes Jim Lillich, DVM, Dipl. ACVS, an associate professor of equine surgery at Kansas State University in Manhattan, Kan. "Racehorse-related injuries are far different than injuries sustained by working horses or pleasure horses."
When you're dealing with animals that weigh 1,000 pounds or more, and all of that weight is supported by four relatively small legs, the number of different types of injuries that can potentially occur is considerable. Many of these injuries fall under the following categories: Tendon and ligament injuries, joint injuries, and, as a further sub-division of joint injuries, soft-tissue injuries around the joint, joint capsule, cartilage, and bone.
Generally, a horse's front legs are more susceptible to injury than the hind legs, Lillich explains. "The front legs take more of a beating, although there are certain horses who experience hind leg problems," he says. "We have quite a few hunter/ jumpers in our area, so we get hind leg suspensory injuries once in a while. They don't necessarily involve a tendon, but a proximal suspensory lesion in the hind leg is a little worrisome." Tendonitis and desmitis are relatively common as well.
Early on in the treatment stage, one of the biggest goals is to prevent the horse from developing mechanical laminitis in his "good" leg--the limb that is taking all of the pressure off of the one that sustained the original injury. This phenomenon is called "mechanical" or "overload" laminitis.
"It's something that we are very fearful of when we have a severe injury to the other leg," says Lillich. "Horses weren't meant to be on three legs, so if they spend all of their time on one (front or hind) leg because the other one hurts so badly, that can really do a horse in." The increased pressure to the uninjured leg prevents blood from flowing to the foot properly, and the trouble begins.
So, how does one prevent this from happening?
"The only way to really prevent it is to make the horse as comfortable as possible on the injured leg," Lillich says. To achieve this, the horse must undergo aggressive treatment during the early stages immediately following the injury. Treatment can include special shoeing to support the hoof, pain medication, joint injections and medications to relieve inflammation and minimize pain, and plenty of rest.
In some cases, recovered horses will injure the same tendon in the other front or hind leg once they have returned to training. "The easy explanation (for this phenomenon) is that they are trying to get off of the injured leg--maybe they had some prior injury that was not picked up in that other limb," says W. Wes Sutter, DVM, MS, assistant professor of equine orthopedics at The Ohio State University. "For example, you may have a really bad bow in the left front and a very mild one in the right front, and you treat the left front but then come back with that injury in the right."
Therefore, it's often advisable to take X rays or do an ultrasound exam of both legs when a horse is presented with a lameness. "I think it's important to do ultrasounds in both sides," says Sutter. "If they have a developmental abnormality, you would usually want to look at the other side. In the case of horses with chip fractures, you would commonly want to look at the other side--although much of this is going to be decided upon during the physical exam."
"If you see a chip fracture in a joint, you had better look at the other limb and make sure that the horse doesn't have the same fracture on the other side," says W. Rich Redding, DVM, MS, Dipl. ACVS, clinical associate professor of equine surgery at North Carolina State University College of Veterinary Medicine in Raleigh, N.C. "This also applies to certain soft tissue injuries, such as superficial digital flexor tendonitis (SDF tendonitis, or bowed tendons). Any injury that can cause a horse to protect a limb can overload the opposite front limb, potentially creating other soft tissue injuries or even fractures of that limb. Surgeons performing superior check ligament desmotomies (used for SDF tendonitis) recommend performing this procedure bilaterally. Inital experience using this procedure for SDF tendonitis on the affected leg had a high rate of flexor tendon injury occurring in the opposite leg the next year."
Medicating the Injured Horse
There are standard medications used for treating leg injuries, but there remains a number of different opinions on which are most effective.
According to Lillich, steroids, when used moderately, are effective in making the horse as comfortable as possible because they reduce inflammation in the joint. "You don't want to give them so many steroids that you damage the tissues, but steroids, every once in a while, in the right place, are a good thing," he says. "You can get the joint working again." However, handlers beware: "The only problem is, if you inject steroids into the joint, they will feel like they can go out and perform again."
Still, Lillich prefers the local injection of steroids as opposed to non-steroidal medications (NSAIDs) such as Bute. NSAIDs don't treat the problem, but mask signs of pain, and if used long-term can pose toxicity problems. "I am not a fan of long-term non-steroidal anti-inflammatories," he says. "There are problems that can occur with some of the healing with non-steroidals. If you're giving non-steroidals, you should probably give them after exercise, but some of the things that they can inhibit are part of the healing process. Inflammation is part of the healing process, and we don't know all of what the non-steroidals do. We are sure that they control inflammation, but there are other things out there that we are not aware of."
Rehabilitation Through Exercise
Not long ago, a horse that had sustained a leg injury was caged up, assigned months of stall rest, and essentially prohibited from moving until the injury had healed. Over the years, this approach has been altered dramatically. Now instead of putting the horse on the shelf, the goal is to get him out and moving as quickly as possible.
"The immobilization of a leg or a joint does a lot of bad things to the normal tissues," Lillich declares. "If you look at what we can gather from human medicine and apply it to rehabilitation in the horse, we can talk about the big fundamentals such as getting them going as soon as possible, and getting them as comfortable as possible."
At the same time, many of the methods applied to rehabilitation in human medicine don't translate that well when treating horses. "If you injure your knee or your shoulder in a certain way, the specialized surgeon will use specific techniques, and they have a rehabilitation regime for you," says Lillich. "That is not likely to be developed in the horse because of size limitations, and direct applications can get a little fuzzy."
Still, there are a number of different answers to the problem. "When you're talking about tendon and ligament injuries, it used to be that they would be prescribed enforced rest, and most of us now feel that approach is not as effective," says Lillich. "With tendon injuries, there are a lot of treatment modalities now: You can use stem cells and shock waves, for example. All of this is still in its infancy, but the goal should be to promote healing for an earlier return to function. Where we win with our tendon injuries is to monitor their progress with ultrasounds and examinations to see how the tendons and ligaments are getting along, then increasing activity very slowly."
Bringing the horse to the point where he can leave his stall for light hand-walking is one of the first major steps along the road to recovery. Owners and trainers might also apply old-fashioned techniques, such as rubbing and massaging the legs, to promote healing.
"That used to be done at the racetrack all the time, and of course there is science to that because it increases blood flow (which facilitates healing)," says Lillich. "With increased blood flow, the horse will eventually become more comfortable using the leg."
If the Shoe Fits...
In a number of cases, veterinarians prescribe supportive shoeing as part of the treatment and rehabilitation program. "I like to make sure that their feet are well supported," Sutter notes. "Commonly, we will add heel support." Heel support will help relieve tension on an injury to the rear of the limb, as well as reduce the pull of the DDFT, so the chances of laminitis are reduced.
Redding points out that some shoeing methods in common use at the track might actually promote the chance of injury. "Certain shoeing procedures might increase the risk of these and other catastrophic injuries occurring," he says. "There have been studies done that examined toe grabs and the increase of suspensory apparatus breakdown in racehorses (including the superficial flexor tendon). An imbalance to the shoes or the feet can predispose the horse to injury, as well as the conditions that the horse is working in."
The footing in a track or a show ring, for example, can make a big difference in whether a horse gets away without injuring himself for an entire career.
Half the battle is bringing an injured horse to the point where he is able to begin light exercise; the other half is creating an exercise regimen and environment that contributes to his recovery.
"Obviously, you want to have them in a dry, clean place," says Sutter. "You don't want to have them in muddy, deep bedding where they will put more strain on their ligaments. You need to have them in a place where you can monitor them rather than kicking them out to pasture."
We have all seen horses on stall rest who seem to do more harm than good by developing aggressive behaviors such as kicking, weaving, and pacing to demonstrate their frustration at being confined for long periods. Even with a regular exercise regimen, injured horses will still be required to take it easy--which means that full turnout is usually not an option. The key to managing this period of convalescence is hands-on care, which demands time and dedication on the part of caretakers.
"We used to think that horses rehabilitated themselves, and I am not sure that is the case for some of our more hot-blooded individuals," Lillich notes. "Some horses do just fine when they are by themselves, and other horses just want to run fast, which is detrimental." Convalescing horses might benefit from forage balls, stall toys, and extra hay to keep them occupied.
The individual who is charged with overseeing the horse's rehabilitation must have a good eye and a strong sense of how far the horse can be pushed on his way to recovery. "The horse needs someone who knows him, someone who can say, 'He's sore today because we pushed our luck yesterday, so we should back off,' " Lillich says.
This same person should also ensure that the horse's surroundings are conducive to healing. "They require a facility that allows the horse to walk so that their speed and activity can be controlled," Lillich says. "A hot walker is a controlled environment, and an arena is fine for some horses."
Generally, the surfaces recovering horses walk on should be soft, but not so deep that walking is difficult. "We want to take the horse out to an area where they can get their blood pumping to the injured portion of their leg, but not push it so hard that they come back and are crippled the next day," says Lillich. "It's a judgment call. There is a fine line and it takes a pretty dedicated individual to know what side of the fence they are on, and then walk that fence."
A convalescing horse requires time and dedication from his handlers, and must be given plenty of time to heal. There are a number of factors that contribute to how long a horse takes to heal, including the nature of the injury, his age, the rehabilitation program, the conditions in which he lives, and his body's individual capacity to heal. Veterinarians and horse owners can only hope to operate within an approximate time frame.
"If you fuse a pastern joint in a horse, for example, and do a very good job of it, the horse usually takes a year to come back and be where he was before the injury," Lillich estimates. "A fractured bone can take four months to heal, and a tendon can take six to eight months."
Along the Way
As time goes on, it's necessary to check in to monitor the horse's healing progress. Radiographs are generally required at several points during the rehabilitation process if the injury is not related to soft tissue. "I recommend X rays post-op, and if it's a joint injury, before we start any real work in earnest," Lillich suggests. "They may walk and trot, but before they start to gallop, I think you should take a picture. You certainly need that X ray before they do any speed work. In the case of an injured tendon, if you are ready to get back to training the horse and putting him through the paces, that is when I would recommend an X ray or an ultrasound."
When in doubt, it's best to err on the side of caution, Sutter notes. "One of the biggest problems that we have--particularly with tendon and ligament injuries--is that once the horse looks good, many trainers will try and get them back to work too early," he observes, emphasizing the need for regular ultrasounds in order to properly monitor the healing process. "If the horse isn't completely healed, the horse won't turn out very well, and in some cases he'll re-injure. When you are rehabilitating a horse with a tendon or ligament injury, you need to be really careful and monitor what that injury might be. Keep a very close eye on it, because it can re-injure anytime during that process, and then basically you have to start all over again." This is to be avoided at all costs.
Once an injured limb is re-injured, the chances of it healing 100% percent grow slim. "Re-injuries are extremely difficult to deal with, because often you have a lot of scar tissue, and there will always be a weak spot," says Sutter.
"Most equine practitioners that are involved with rehabilitation of horses with tendon and ligament injuries have incorporated diagnositc ultrasound as a vital part of the horse's rehabilitation process," continues Sutter. "This has allowed us to assess the remodeling process (an indirect assessment of the strength of the healing tendon or ligament) that happens with exercise.
"The use of diagnostic ultrasound has been very effective in getting many horses back to work faster than had been thought possible," he concluded.
If the limb is re-injured several times, the chances of it ever healing properly diminish severely. "After they have re-injured themselves two or three times, you get to the point where a couple of years down the road the owner is reluctant to put them through another period of convalescence and controlled exercise," he says.
Like many processes, rehabilitating an injured horse is a serious commitment, demanding both financial resources and time from owners and trainers.
Ultimately, the horse has a better shot at a full recovery if his caregivers are committed to investing not just money, but time--and lots of walking. "What we initially try to do (with a tendon or ligament injury) is hand-walk the horse," Redding explains. For the first three weeks following the acute injury, the horse will be on strict stall rest, then the horse is hand walked for 20 minutes a day, adding five minutes a week out to the sixth to eighth week post-injury. "At that point, it's time to re-evaluate the structure with an ultrasound, and then we can start guiding ourselves as to what kind of load the tendon is going to be able to withstand."
"A dedicated individual can do a lot. If you have an owner or a trainer who wants to make it happen, they can work with the horse and do it," says Lillich. "It's a time-consuming process that requires a lot of management. It would be great to go back and pick the brains of the old classic horsemen in the 1920s, '30s, and '40s, when medications were not as well known, to see what they did to get horses back into shape. They rubbed legs and used a lot of alcohol sweats and poultices, and they spent a lot of time and energy under the horse, as well as on it."
MANAGING LEG INJURY REHABILITATION
Stem Cells for Tendon Repair
A yet-unpublished study of using stem cells for tendon repair, completed at Cornell University by Alan Nixon, BVSc, MS, Dipl. ACVS, chief of surgery at Cornell, and Linda Dahlgren, DVM, PhD, Dipl. ACVS, of Cornell's Comparative Orthopedics Laboratory, School of Veterinary Medicine, found improved healing with fat-derived stem cells. The double-blinded, placebo-controlled study evaluated eight horses with collagenase-induced tendon lesions (four treated with stem cells prepared by Vet-Stem and four controls treated with saline) mimicking natural tendonitis.
Ten days post-injury, the four study horses' lesions were injected with autologous (made from each horse's own tissue) stem cells from tailhead area fat tissue. Ultrasounds of all animals were done weekly and all horses were sacrificed for dissection six weeks after injury.
The researchers found the following statistically significant differences between study horses and controls:
- Inflammatory cell infiltrate: None in treated, slight to moderate in controls. Demonstrates the anti-inflammatory effect of the cell therapy (p=0.01).
- Collagen fiber uniformity: Significant improvement in architecture with improved uniformity of collagen fibers (p=0.01).
- Polarized collagen fiber crimping: Significant improvement in the crimp observed under-polarized light, indicating normal cross-linking of collagen (p=0.04).
- Overall tendon healing score (9 parameters): Statistically significant improvement in the stem cell-treated group shows the overall benefit in improved healing of the tendons (p=0.03).
Researchers also noted the following trends, although none were statistically significant:
- Collagen fiber linearity: Improved, nearly statistically significant.
- Tendon cell shape: Linearity of shape more like normal tendon.
- Tendon cell density: More normal sparse tenocyte density.
- Free hemorrhage: Reduced hemorrhage.
- Lesion size on ultrasound: Reduction in lesion size in nucleated cell treated compared to controls as a percent of starting lesion size.
- Lesion grade on ultrasound: Lesions in nucleated cell-treated horses had a lower grade for most of the study compared to controls despite starting at an equivalent (or higher) value.
- Linear fiber pattern on ultrasound: Improved linear fiber pattern was seen with trending towards significance.--Christy West
About the Author
Carolyn Heinze (carolynheinze.blogspot.com) is a freelance writer/editor. She currently works from her pied à terre in Paris, France, where she continually dreams of convincing the French Republican Guard to let her have a go-round on one of its magnificent horses. One can dream, can't they?
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