It was two days after the 4th of July when I decided to take my horse Milagro for a ride alone on the trail. We live in an equestrian community with well-groomed bridle paths, and I planned to have him out for about an hour. We were only about half a block from home when it happened.

I heard a car coming down the street we had just turned off. One minute I heard the motor, and the next minute, a loud pop. Someone had thrown a firecracker out of the car window in our direction.

Milagro is solid on the trail—he’s my North American Trail Ride Conference (NATRC) competitive trail horse—but firecrackers are his nemesis. He bolted in terror, racing up the trail at a mad gallop, away from the sound.

In an effort to stop him, I turned his head and pushed him with my leg into a tight circle. But the bridle path that once seemed wide and safe was not big enough for a terrified, runaway horse.

As I turned him, his back hoof landed on the sloped driveway of one of the homes adjacent to the trail. I felt his back end going down. He scrambled and got his feet under him, but not before he let out a horrible scream.

I jumped off and examined his back legs. I didn’t see anything obvious, even as I led him home. His adrenaline was racing, and he was practically dragging me.

An hour later in his paddock, he had calmed down. It was then that I noticed he was dragging his left hind toe. I called out the vet, who examined him by lifting the affected leg and stretching it out behind him. Instead of bending at the hock, the leg extended straight out in a way that turned my stomach.

“He’s got a rupture of the peroneus tertius tendon,” my veterinarian said.

How Tendon Injuries Happen

Tendon injuries can occur in two ways: through chronic overuse, or through trauma. Because horses’ legs are made up of a number of tendons, they are prone to stress and injury.

“Tendon injuries result from sudden tears or ruptures from a single overloading event, or chronic strains from overuse,” says Annette McCoy, DVM, M.S., Ph.D., Dipl. ACVS, associate professor of Equine Surgery at the University of Illinois College of Veterinary Medicine.

“The former are usually recognized right away after an athletic episode, and usually have the hallmarks of heat, focal pain when touched, and obvious swelling,” she explains. “The latter can result in low-grade chronic lameness that can be difficult to diagnose.”

The most commonly injured tendons and collateral ligaments that support joint stability in non-racing horses are the suspensory ligament, deep digital flexor tendon, the check ligament and the superficial digital flexor tendon, according to Jennifer G. Barrett, DVM, Ph.D., DACVS-LA, DACVSMR-EQ, Theodora Ayer Randolph professor of Equine Surgery at Marion duPont Scott Equine Medical Center at the Virginia Maryland College of Veterinary Medicine.

Varied Treatment of Tendon Injuries

The way a tendon injury is handled right after it’s discovered can make a big difference in the ultimate outcome.

“Right after an injury happens, we are trying to combat inflammation and swelling,” says McCoy. “This is accomplished with a combination of cold therapy like icing or cold-hosing, compression with bandaging, systemic medications like a non-steroidal anti-inflammatory drug [NSAID] such as phenylbutazone [bute], and stall rest.”

Although scarring of the tendon as it heals cannot be prevented, making the scar tissue as functional as possible is the goal.

“Controlled exercise in a rehabilitation program helps us to do that,” says McCoy. “Periodic re-evaluation with ultrasound helps us determine the healing progress. A rehab program might need to be altered, depending on how the tendon is healing.”

A number of adjunct therapies can also be used to help tendons heal, including extracorporeal shock-wave therapy, therapeutic ultrasound, and low-level laser and magnetic therapy, although not all of these therapies have been studied in clinical research.

“Biological therapies such as platelet rich plasma [PRP], autologous conditioned serum, and mesenchymal stem cells injected directly into a tendon injury under ultrasound guidance have shown some promise at either speeding healing, improving the quality of the healed tissue, or helping to reduce the incidence of re-injury,” says McCoy.

“More work is needed to understand exactly how these treatments work, and what injuries are best addressed by using them,” she adds. “This is a very active area of ongoing research.”

There are some tendon and ligament injuries that can benefit from surgical treatment, according to Barrett.

“Examples include the suspensory ligament in hind limbs, the deep digital flexor tendon, and superficial digital flexor tendon when they are injured in a tendon sheath or bursa,” she says.

Slow Recovery

When a horse injures a tendon, the issue can require a temporary layup or permanent retirement.

“Prognosis is entirely dependent on the severity and location of the injury, but typically ranges from fair to guarded for future athletic use,” says McCoy. “An owner should expect that their horse will be out of full work for nine to 12 months while the injury heals. Unfortunately, horses that have had a tendon injury are highly prone to re-injury.”

The way the layup and rehabilitation are handled can make a huge difference in whether the horse is able to return to his previous activity.

“The hardest thing for owners to understand is that healing takes a very long time for tendons and ligaments,” says Barrett. “Humans can rest by taking the weight off the limb completely. This is not possible for horses, so we rely on reducing exercise as much as possible during healing.”

Stall rest is the best we can do to limit trotting and overuse of a healing tendon, but stall rest is hard for owners, and is often seen as hard for horses too, according to Barrett.

“The same way you need to be on crutches to heal a tendon, horses need stall rest and very controlled exercise once your veterinarian determines it appropriate,” she says. “All of the difficult and expensive care your veterinarian provides [might] be wasted if the exercise recommendations are not followed.”

The length of stall rest and the limited exercise needed to help the horse recover depends on the injury. Extensive stall rest is usually prescribed early in recovery, with a gradual return to gentle exercise as the tendon heals.

“Early loading—exercise—of the tissue is the most essential aspect of healing, but we can’t load too much, otherwise it breaks again,” says Henk Offereins, DVM, of equinetendon.com, an Ireland-based equine management service specializing in the area of tendon injuries. “Getting that balance right [is the difference between] success and failure in rehabilitation.”

Update on Milagro

Milagro made a full recovery after rupturing his peroneus tertius tendon, but only after a one-year layup that required three straight months of stall rest with physical therapy on the affected leg. He eventually graduated to hand-walking, slowly building up the amount of time he could be walked over a period of months.

Today, he is back to trail riding around our community as well as competing in NATRC events. He is so sound these days, I often forget he ever suffered this horrible injury. I believe the long layup and following my veterinarian’s instructions on rehabilitation made all the difference.

Key Takeaway

Tendon injuries are as complicated as equine injuries come—and certainly time-consuming to recover from. Understanding treatment options and the recovery timeframe can help horse owners and caretakers to better manage any future tendon injuries.

Further Reading:
◆ Managing Horses with Tendon and Ligament Issues
◆ Taking Care of Your Horse’s Tendons

This article about equine tendon injuries appeared in the April 2024 issue of Horse Illustrated magazine. Click here to subscribe!

The post Treatment of Equine Tendon Injuries appeared first on Horse Illustrated Magazine.

Seeing the full picture of a horse’s body from the inside began not with a hoof, but with a woman’s hand. The accidental discovery of the radiograph in 1895 by the German physicist Wilhelm Conrad Röntgen transformed the human medical landscape. Still another century passed before advancements in equine diagnostic imaging revolutionized veterinary medicine.

Accurate, safe, and comprehensive imaging, including computed tomography (CT), magnetic resonance imaging (MRI), nuclear scintigraphy (bone scan), and the emerging positron emission tomography (PET) scan may redefine horse health today, but it has only accelerated at a rapid rate during the past 25 years.

X-Rays and Ultrasound

Early radiographs (X-rays), while groundbreaking for both human and equine medicine, rendered complications. The analog film required wet processing and often lacked sufficient image detail and quality. Delays between image development and delivery to medical professionals impeded swift diagnoses. However, with the advent of portable digital machines, equine practitioners can now capture high-quality images of bone at a horse’s stall rather than in a veterinary clinic.

Later, ultrasound technology came onto the scene, employing high-frequency sound waves to produce high-resolution, two-dimensional images of tendons and ligaments. With the ultrasound, veterinarians can assess soft-tissue injuries, colic, pregnancy, and suspicious masses, such as abscesses and tumors. Advanced speed and the accuracy of high-resolution, two-dimensional images improve physical exams.

CT and MRI

Equine diagnostic imaging rocketed to the next chapter with the introduction of CT and MRI in the 1990s, according to Katherine Garrett, DVM, Dipl. ACVS, director of diagnostic imaging at Rood and Riddle Equine Hospital in Lexington, Ky.

“The most significant change in equine diagnostic imaging is the widespread adoption of cross-sectional imaging modalities,” she says. “Their introduction allows us to make much more specific diagnoses than we could previously and understand different diseases more thoroughly.”

The difference between the traditional X-ray and a CT scanner lies in the type of image. A CT scanner examines slices of bone and soft-tissue structures on multiple planes from multiple angles and is beneficial for diagnosing cases of lameness and sinus, dental, and neurological issues.

Traditional CT scans performed on a fully anesthetized and recumbent horse presented its share of risks. The standing CT scans lower legs and images the head and neck. Because the horse only requires mild sedation, fewer complications and threats to the horse and the clinician occur.

Sarah Puchalski, DVM, Dipl. ACVR, head of Diagnostic Imaging at Palm Beach Equine Clinic in Wellington, Fla., cautions horse owners to understand how different types of image qualities vary between scanners.

“There is a difference in image quality for CT scanners, and what can and cannot be scanned,” she says. “CT is used for dentition in the skull and fracture evaluation. Soft tissue detail isn’t as good as the MRI, but the bone detail is superior.”

Soft-tissue injuries present a puzzle, especially in cases of lameness. MRI, first performed on horses in the late 1990s, benefitted from early clinical use but shot to the top of imaging modalities in the past five years. Today, MRI is considered the gold standard of diagnostic imaging for soft tissue and orthopedic injuries by using magnetic fields and radiofrequency pulses to generate images.

Puchalski notes that the particular benefit of the MRI rests in diagnosing the source of lameness.

“For example, inside the hoof capsule, you cannot evaluate tendons and ligaments,” she says. “MRI opened the door for a whole range of new injury diagnoses allowing specific target therapies.” Garrett concurs.

“With the MRI, we obtain detailed information about an entire region,” she explains. “Deep digital flexor tendon tears, navicular bone inflammation, bone bruising, and coffin joint arthritis have different treatments and prognoses. We can diagnose and treat each more specifically and hopefully have better outcomes.”

Bone Scans and PET Scans

Nuclear scintigraphy (bone scan) employs radioactive isotopes, which, when injected, emit radioactive gamma rays. A special camera documents two-dimensional images of skeletal anatomy, showing areas with increased metabolic activity.

Reactive sites light up as “hot spots” to identify sources of lameness or other injuries. Evaluating a tissue’s physiology or what is occurring inside the tissue distinguishes the bone scan from other methods.

Scintigraphy, according to Puchalski, allows a clinician not only to identify sites that may not be clinically evident but provides an opportunity to use disease-modifying agents earlier.

“Hock arthritis shows up on scintigraphy early,” she says. “Scintigraphy also allows us to evaluate the neck, back and pelvis. A higher degree of radioactivity in an area means more active bone turnover, inflammation or injury.”

Mathieu Spriet, DVM, M.S., Dipl. ACVR, Dipl. ECVDI, Dipl. ACVR-EDI, associate professor of Diagnostic Imaging at the University of California-Davis School of Veterinary Medicine, recalls the trajectory of equine imaging during his lifetime.

“When I was in graduate school in France, the only imaging modalities we had were X-ray and ultrasound,” he recalls. “In the last 25 years, we’ve had digital radiographs, CT and MRI. I’m excited to contribute another piece by bringing the PET to the table.”

PET scans add a new chapter to nuclear medicine imaging. A radioactive tracer injected in the horse shows activity in the bones and soft tissues at a molecular level by detecting “hot spots” that illuminate injury, functional change, or inflammation on images.

The defining concept of the PET scan is the distinction between functional versus structural imaging.

“With most imaging, you are looking at the size and shape of structures,” says Spriet. “When the bone looks abnormal, it’s sometimes difficult to know if it’s abnormal because something is happening right now or if there is an old injury that is not currently active.”

To perform the first equine PET scan in 2015, Spriet and his research team partnered with an engineering team from Maryland-based Brain Biosciences, a company specializing in state-of-the-art molecular brain imaging devices. A clinical program employing a modified human scanner imaged over 100 anesthetized horses with lameness issues.

Anesthesia carries its own level of risk to both the horse and the owner’s pocketbook. Four years after introducing the first scanner, a standing PET for a mildly sedated horse advanced this up-and-coming technology. With a standing PET, a clinician positions the horse’s hoof into an open doughnut-shaped ring before closing the apparatus around the leg. The ring’s detectors capture images from the hoof, but it can open automatically if the horse moves.

The radioactive isotope is injected 30-60 minutes prior to bringing the horse in to the room. In less than half an hour, a PET scan can image both feet and fetlocks. With an MRI scan, 45 minutes per foot or fetlock is necessary.

A Game-Changing Future

Kelly Tisher, DVM, a Colorado-based veterinarian and clinic partner at the Littleton Equine Medical Center, envisions future technology to scan a horse’s total circumference. According to Tisher, several companies are actively working to create and improve standing technology, including a robotic CT machine.

“We’ve been hoping there would be an advancement in technology to allow standing CT imaging, especially for a horse’s head and neck,” he says. “Head imaging for sinus, teeth, or other tumors is tricky. With the neck, we have an ultrasound and X-ray. Still, the ability to have 3D imaging and some sectional imaging and transverse imaging to learn about what different pathologies mean and what their clinical relevance is would be amazing.”

Each year, seeing the full picture of a horse’s anatomy to diagnose injury and disease matures. Century-old curiosity ignited a medical revolution, and today, veterinary researchers are casting light on more than a horse’s hoof.

This article about equine diagnostic imaging appeared in the January/February 2022 issue of Horse Illustrated magazine. Click here to subscribe!

The post Advances in Equine Diagnostic Imaging appeared first on Horse Illustrated Magazine.

Tendon and ligament injuries are among the most common and concerning injuries that affect athletic horses of all breeds and disciplines. Injuries such as a bowed tendon or strained suspensory ligament carry fear, sadness, and frustration for horse owners who may be concerned that such injuries mean the end of their horse’s riding career.

What is a Tendon or Ligament?

Structurally, tendons are ligaments are similar to ropes. That is, they’re one large fibrous structure made up of many individual fibers. They are critical in supporting and/or transmitting forces throughout the horse’s musculoskeletal system. There are dozens of tendons and ligaments in the horse’s body, although the ones that are of most common concern are in the horse’s lower limbs.

Tendons connect muscles to bones. When muscles contract (which is the only thing that muscles can do), the force of contraction is transmitted to the bones via the tendons.

Ligaments, on the other hand, connect bone to bone. Ligaments are like shipping tape used to hold two boxes together (with the boxes being bones in this analogy). Ligament functions are more passive than those of tendons, but certainly no less important.

How do Tendon and Ligament Injuries Occur?

In general, injuries to a horse’s tendons or ligaments occur in one of two ways: suddenly, or over time. Sudden injuries are perhaps easier to understand, and occur after a single incident or accident where the forces placed on the horse’s limb exceed the strength of the tissue.

An awkward step, unexpected blow, or misplaced limb can result in immediate and obvious damage to a tendon or ligament, usually resulting in swelling, pain and lameness. However, sudden injuries appear to be the exception rather than the rule.

Most tendon and ligament injuries occur over time from chronic stress and fatigue to the tissues. Stress and fatigue is what causes a paper clip to break when it is bent back and forth repeatedly. A single bend causes no apparent damage or weakness; repeated bending in the same place causes the clip to weaken and snap.

Repeated stress to tendons and ligaments without adequate time for rest and recovery, such as can occur when horses are overtrained, causes strain and injury to the tendon or ligament fibers. While the damage can be occasionally be catastrophic, in most cases only a relatively small percentage of the fibers are damaged.

How are Tendon and Ligament Injuries Diagnosed?

It’s usually not difficult to see the signs of injuries to tendons and ligaments. They are often accompanied by signs of inflammation that have been recognized since the days of the Romans.

• Swelling: Swelling occurs due to bleeding and fluid movement into tissues. The swelling of lower-limb tendon injuries gives rise to the common term “bowed” tendon: the contour of the injured tendon bows out from the swelling. In other cases the swelling is not so obvious, such as with an injury to a tendon or ligament inside the horse’s hoof.
• Pain: Injured tendons and ligaments are painful. Pain causes gait abnormalities (limping) that are most commonly seen at the trot. Swollen, injured areas may also be painful to the touch, or flexion of the limb may compress injured areas and lead to pain when a horse is trotted off after the limb is flexed for a short period of time.
• Heat: Although perhaps harder to detect, inflamed and injured tendons and ligaments are demonstrably warmer than surrounding tissues. While investigators have tried to take advantage of this fact by using instruments that detect heat as diagnostic tools, so far, these tools have not been widely employed by the veterinary community, as their accuracy and reliability is suspect.
• Redness: The fourth classic sign of inflammation is rarely diagnostic in the horse due to thick, pigmented skin and the hair coat.

In the 1980s, ultrasound was introduced to help diagnose tendon and ligament injuries. Ultrasound has revolutionized care of these injuries. Ultrasound allows for earlier diagnosis, as well as the ability to monitor injuries through the recovery period.

What Treatments for Tendon and Ligament Injuries Work Best?

In humans, the gold standard for immediate treatment of tendon and ligament injuries is known as RICE therapy:

• Rest: Horses with tendon and ligament injuries should be rested in the immediate post-injury period.
• Ice: Ice constricts blood vessels and slows down the process of inflammation. Ice can be applied for periods of 30 minutes and should be applied several times a day. There are no benefits gained from icing injured tendons and ligaments for more than three days.
• Compression: Bandaging helps keep the swelling down, which may help prevent further disruption to the injured tissues. There are also compression devices that can be applied to the limbs; these devices can help cool the limb.
• Elevation: In humans, the “E” in rice stands for elevation of the limb. Elevation keeps fluid from collecting in the injured area. Obviously, this isn’t an option for horses.

Medication to control pain and inflammation, such as non-steroidal anti-inflammatory drugs, are also a cornerstone of post-injury therapy. The goal of such medications is not necessarily to make the horse pain-free; rather, it is to help control the inflammatory response. The use of such medications should be short-term and as prescribed by a veterinarian.

After the acute injury has been treated, successful rehabilitation usually requires several months of controlled, increasing exercise, depending on the severity of the injury. Exercise increases both in time and intensity as the injured limb heals.

Monitoring of the healing process by serial ultrasound examinations is often recommended to make sure that the rehabilitation process is occurring without making the injury worse.

Do You Need to Use Expensive Treatments for the Best Results?

Tendon and ligament injuries can be frustrating in horses because they don’t heal with normal tendon and ligament tissue. The tissue that replaces the normal type 1 collagen is a different type, called type 3 collagen, which is neither as strong nor as elastic.
Recovery can take a long time. For decades, people have looked for ways to get tendon and ligament injuries to heal more quickly and with a better quality of repair.

There are few parts of the horse that have received more therapeutic attention than the tendons and ligaments. The past several decades have seen the rise and fall of therapies such as tendon splitting and stabbing, laser therapy, various light devices, magnetic boots, pulsating magnetic field therapy, Bapten (an injectable therapy thought to help direct the healing process), Adequan, bone marrow injections, and many others.

More recently, therapies optimistically and perhaps disingenuously referred to as “regenerative” have entered the fray, leading to treatments with therapies such as platelet rich plasma or any number of stem cell regimens (which themselves are now under increasing scrutiny).

To date, the only thing that can be said about such therapies is that, in spite of their enthusiastic, optimistic, earnest promotion and application, none have been shown to increase the quality of repair or decrease the time required for recovery injury compared to the tried-and-true methods of rest and rehabilitation. And all of them increase the cost of care.

How Long Does Rehabilitation Take?

As with any injury, the prognosis for recovery and the time needed for successful rehabilitation of tendon and ligament injuries is directly related to how severe the injury is. The more damage that is sustained, the more difficult it is for the horse to recover.

The prognosis for recovery is also dependent on what is expected of the horse after injury; the prognosis for a horse to go back to pleasure or trail riding after an injury is far better than that for a racehorse that will be running at full speed. In fact, racehorses with tendon or ligament injuries may go on to find happy and useful homes post-racing as pleasure and trail horses.

Can a Horse Ever Be Considered Completely Recovered?

Although tendon and ligament injuries do not heal with normal tendon and ligament tissue, repair tissue is usually strong enough for horses to fully return to athletic performance. Of course, there are many individual exceptions:

• Horses that are expected to work to the limits of their capacity, such as racehorses, have a much more difficult time recovering from injuries to the digital flexor tendons than do other horses.
• Jumping horses that have injured a hind limb suspensory ligament may have difficulty staying sound because they will be asked to jump again on a ligament that is weaker than normal.
• Horses with poor conformation or genetic conditions such as degenerative suspensory ligament disease (DSLD) may have trouble recovering because of inherent structural problems.

Understandably, tendon and ligament injuries are one of the injuries of most concern to horse owners. Unfortunately, none of the many therapeutic options that have been presented over the past several decades have resulted in measurable improvements in the quality or speed of healing.

Fortunately, and although there are notable exceptions, most horses that suffer from such injuries can go on to lead productive athletic lives after a slow and careful recovery.

This article originally appeared in the September 2018 issue of Horse Illustrated magazine. Click here to subscribe!

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