Suspensory Injuries in Horses

Suspensory Injuries in Horses

Last Updated on February 19, 2022 by Allison Price

However, a torn suspensory nerve can end your horse’s career. Early diagnosis and treatment can make a difference.

The suspensory ligament is stretched to allow the horse’s fetlock to sink under his weight. It absorbs shock and then springs back when he gets off the leg. (c) Amy K. Dragoo/aimmedia

Although your jumper completed a round without incident, you knew he was not right as soon as he started to trot. He’s now cooled down and back at the barn. However, he doesn’t respond to hoof testing or when you probe his legs with your fingernails. What’s the problem?

You have been hard at work training your horse and perfecting his collected trot for a upcoming show. He looked fine yesterday, although he was a bit off in his left hind. There is no heat or swelling. Do you push on or let him go?

A torn suspensory or ligament injury, which can limit your horse’s ability to perform well in either of these situations, is an unwelcome possibility. It plays an important role in supporting the horse’s fetlock. However, a torn suspensory ligament is not always possible to heal. However, a suspensory doesn’t always turn out to be a disaster. We asked Elizabeth Barrett, DVM, Hagyard Equine Medical Institute’s sporthorse veterinarian, to share her experience with how a careful combination of rest, treatment and rehabilitation can help horses make a full recovery.

Dr. Barrett said she sees two types suspensory issues in her practice. The first is a chronic degenerative condition, which mainly affects older horses from certain breeds. Here, the second is strain injury. She says that suspensory injuries are quite common in horses competing in any discipline, not just jumping. “Any athletic horse is at high risk.”

Suspensory Injuries in Horses

How it happens

The suspensory is responsible for stretching to allow the fetlock to sink under the horse’s body weight. It absorbs shock and then springs back when the horse’s leg moves. It is a fibrous elastic band that starts just behind the knee. Then it runs down the backbone of the cannon bone, splitting into two branches. The branches attach to the sesamoid bones at fetlock and wrap around the joint, one inside and one outside, to anchor below fetlock on long pastern bone.

(c) Illustrated Atlas of Clinical Equine Anatomy

The suspensory is not an all-purpose device. A team of ligaments, and other structures supports the leg. But it’s an important player. If the horse over-exerts its leg, it may give way. Any ligament can sustain injury.

* A high, or proximal tear is when fibers of the ligament are ripped at or near the point where it originates at the top or bottom of the cannon bones. Sometimes, a little bone may be ripped away or a crack in the bone.

* A body tear is a ligament that tears between the point it leaves the cannon bones and the point it branches. The tip of the cannon’s splint bones may be irritated, yanked or even broken by this.

* It is possible to have branch tears in either one or both branches. Sometimes, a little bit of one of the sesamoid bone bones can be broken off during the process. Severe breakdown is when the branch breaks off a sesamoid, which can be dangerous in racing, but not in other sports.

Any activity that puts stress on the leg increases the chance of injury. Speed, jumping, a lot of work in collected gaits (stressing your hind limbs), or simply taking a bad step on uneven ground are all possible causes. “Weight is an important factor. Dr. Barrett states that more weight puts stress on the ligament so an overweight horse is at higher risk. Crooked feet (toeing in and out), unbalanced trimming, shoeing, or improper trimming can all stress the ligament, particularly the branches.

Dr. Barrett says that horses in different disciplines are more susceptible to different types suspensory injury. Dr. Barrett says that studies show that dressage horses are more susceptible to injury at the origin of the ligament than jumpers. However, researchers at the Animal Health Trust Equine Center (Britain) found that dressage horses are less likely to sustain proximal hind-limb suspensory injuries.

Trouble Signs

Horses can become lame on an injured leg. However, the lameness may not be obvious or subtle. It depends on the severity of the injury to the ligament. A severe injury to the ligament can result in a rupture or core lesion. This will leave the horse unable to walk. A few fibers may tear, and the horse might be barely off after a mild injury. It is possible to ignore subtle lameness. He’s more likely to inflict a more serious injury if he continues to stress the ligament.

A lot of work in collected gaits can stress the hind limbs, increasing the chance of sustaining a suspensory injuries. (c) Amy K. Dragoo/aimmedia

The location of the tear can also affect the signs.

A torn suspensory tree may cause swelling on the injured side. The area may also be sensitive to pressure and warm. Lameness can be more apparent if the outside branch is torn when the horse rides with the injured leg on an outside circle.

* Heat, swelling, and sensitivity in the lower leg just below the cannon bones on either side suggest a body injury. However, these signs could be subtle.

* A high suspensory tear is unable to detect any other signs than lameness. The origin of the ligament is concealed behind other structures such as the flexor tendon and the splint bone. It may be easier to see the lameness when the horse is going downhill.

These injuries can be difficult to spot because of the many structures that are packed into the lower leg and around the suspensory. Even with severe injuries, signs can be difficult to spot. Similar heat and swelling can be caused by bruising, infections, and injuries to the tendons. A thorough exam by your veterinarian, including flexion tests and local nerve block testing, will help to pinpoint the problem. An ultrasound scan can pinpoint the problem and show the extent of the damage to the ligament. X-rays will also reveal if there is bone.

R&R Recovery

Ligaments heal slowly and often heal with weak scar tissue instead of the damaged stretchy tissue. For the best results, consult your vet to create a rehabilitation and rest program for your horse. Dr. Barrett states that the details of your horse’s rehabilitation program will depend on the severity and location of his injury. However, these are the essential elements.

First, reduce heat and swelling. One option is cold hosing. (c) Dusty Perin

Cool Down: Heat, swelling and other signs of inflammation can hinder healing. First, you need to reduce them. Dr. Barrett states that cold and pressure can be helpful at first. You can use a Game Ready(r) device to apply them. Or, you can do it the old-fashioned method with cold hosing or frosting and standing wraps. A short course of nonsteroidal anti-inflammatory drugs may be recommended by your veterinarian.

Stall Rest: Horses should be completely confined during the cool down period. This can last from two weeks to one month depending on the injury. Exercise can aggravate suspensory injuries. Healing cannot begin if the fibers are tugged and yanked constantly.

Walking: Once the injury has subsided, and the vet gives you a green signal, you can start to walk your horse under saddle or in hand. Walking aids in healing and increases circulation in the leg. It’s also important in another way. Dr. Barrett states that controlled exercise improves the flexibility of the ligament fibers, making them more resilient to stress and less susceptible to reinjury. Begin with 10 minutes, then increase your time gradually over the next few weeks.

Rehabilitation: Once again, get the vet’s approval to slowly ease your horse back into work. After a few months of walking, you may start to increase the trot intervals. If the horse continues to improve, you can gradually increase the intensity and length of the work. You can extend the process over several months.

Rechecks Repeated ultrasound exams are essential for every stage of recovery. Even though the ligament may be fully healed, your horse will still appear sound. Ultrasound scans can help you determine what is going on inside. They will show signs of lesions filling up and the fibers becoming more dense and uniform as the ligament heals. Dr. Barrett states, “I like to reassess the horse with ultrasound every 30-60 days or if there is any sign of reinjury in the rehabilitation.”

It’s impossible to speed up the process and it is dangerous to put the horse back on the job before he heals. It’s also a bad idea to let the horse go too soon. Even the quietest horse can explode after being in confinement for months. Wait until the vet gives you permission.

How long does healing take? Dr. Barrett suggests that you can expect a full recovery to take anywhere from six months up to one year. Your horse’s recovery time will depend on how severe his injury is (whether it’s a tear in a few fibers, a core lesion or a broken bone), what level of work he can return to and where the injury occurred.

Dr. Barrett explained that injuries at the origin can take longer to heal than those resulting from body or branch injuries. Facia (bands made of fibrous connective tissues) surround the ligament, creating a type of compartment. A condition known as compartment syndrome, where blood flow is restricted by swelling in the compartment, can be caused. She says that this slows down healing. It can also be painful.

Extra Help

Dr. Barrett states that nothing can replace rehabilitation and rest, or reduce the healing time of an injured ligament. However, there are several treatments that can help the ligament heal as quickly as possible. These treatments are usually given after the horse has been cooled down and before the horse goes back to work.

Shock-wave treatment may increase blood flow to the injured area. They can also temporarily analize the area. (c) Dusty Perin

Extracorporeal Shock-wave Therapy: Shockwave treatments use high-energy pressure waves to bombard the injured area. They can increase blood flow to the affected area. They may also temporarily analize the area, which can mask pain. However, it is important to not mistake this effect for evidence that the ligament has been healing rapidly.

ESWT can either be performed in a clinic, or in the stable with the horse sedated. The horse usually receives three treatments, spaced out over a period of two to three weeks. Dr. Barrett states that she will follow the treatment with an ultrasound exam in order to evaluate progress and then continue with rehabilitation.

Other complementary therapies can be used to improve blood flow to the ligament. This may be possible with therapeutic ultrasound, which uses sound waves at higher frequencies than those used in ultrasound imaging. Laser and light therapy, as well as magnetic devices, may also be used. However it is not clear if any of these treatments will improve healing. Dr. Barrett states that most treatments do not cause harm but that there’s little research to prove they are beneficial.

Regenerative therapies These therapies make use of cells taken from horses in order to encourage the growth of healthy tissue. These therapies are still in development and are being evaluated for long-term health benefits. Dr. Barrett believes they are an option for those suffering from severe injuries such as those with core lesion. These involve injecting platelet-rich plasma, bone or stem cells at the injury site.

Plasma (the liquid of blood that is straw-colored) contains high levels of platelets. Platelets are blood cells that release growth factor that stimulate healing. Also rich in growth factors and bone marrow, it is one of many types of tissue that contain stem cells. The other is fat. Stem cells can transform into many types of tissue. Suspensory injuries can lead to stem cells becoming fibroblasts. These cells produce collagen proteins which make ligaments elastic.

Dr. Barrett believes that stem cells could provide a better foundation for healing. She notes that regenerative treatments are costly because they require the horse to be culturing their own cells and an ultrasound-guided injection. Although costs vary from one area to the next, PRP and bone-marrow treatments usually cost less than three shock-wave treatments and slightly more than stem-cell treatments.

Surgery: surgery is an option for stubborn cases which resist healing. Dr. Barrett said that surgery is more common in cases of high hind suspensory injury, which are often not as responsive to shock-wave or rest treatment as forelimb or branch injuries. These cases offer two options for surgery:

* Desmoplasty: The surgeon makes small incisions in the ligament. This is done to increase blood circulation and improve healing by stimulating the growth of blood vessels. Dr. Barrett states that this surgery is less common than it was in the past.

* Fasciotomy, sometimes with or without neurectomy for the deep branch the lateral nerve. Fasciotomy is a procedure that removes the tough band of tissue encapsulating the top of the ligament between two splint bone bones. This relieves compartment syndrome. Pain relief is provided by the neurectomy, which involves removing the deep branch from the lateral nerve. The nerve branch is only used to relieve pain in the suspensory.

Dr. Barrett states that the combination of fasciotomy/neurectomy has an 85% success rate for chronic high-hind suspensory injuries. It’s safe for most horses. However, horses with straight hocks and dropped fetlocks should not be considered for this procedure as they can sustain further injuries.

Outlook

Even severely torn ligaments can heal with time and care. Dr. Barrett states that although scar tissue may not be as strong as original ligament tissue, it is possible to make the horse recover. She adds that patience is key. “If the horse returns to work too fast, he could reinjure the ligament.”

Regenerative therapies such as platelet rich plasma are costly because they require the horse to be culturing his own cells and an ultrasound-guided injection. (c) Amy K. Dragoo

You’ll need to keep an eye on the leg for signs of reinjury. If you don’t already, start a daily hand-on leg check. This involves running your hands along the legs and gently probing with your fingers. Compare opposite legs to identify heat, swelling, or sensitivity. Be alert for any subtle lameness. Give the horse some rest if you suspect you are in trouble. Ask the vet for a check-up if the signs don’t go away or return when the horse goes back to work.

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