Equine Sports Medicine

Equine Sports Medicine

If you ask someone “what is sports medicine?” you are liable to get many different answers. In its broadest interpretation, the term means any type of medical or surgical procedure used for athletic horses. This usage would include all of equine medicine and surgery. The term as normally used means “the diagnosis and treatment of sports related injuries”.

Arizona Equine has a number of specialists that practice Equine Sports Medicine exclusively. These specialists include Drs. Rick Howard, Scott Taylor, and Ed Voss. Drs. Howard and Taylor are board certified by the American College of Veterinary Surgeons and have been practicing equine sports medicine since 1990. Dr. Voss is board certified by the American College of Veterinary Internal Medicine, and has been practicing equine sports medicine since 1992. All three doctors completed four years of extensive training after veterinary school in their respective specialties. Dr. Howard also obtained a PhD and conducted research into equine joint disease for a number of years after his surgical residency. Drs. Howard, Taylor, and Voss work predominantly in the clinic while working up sports related injuries. Dr. Gayle Leith is a boarded member of the American Board of Veterinary Practitioners – Certified in Equine Practice. Dr. Leith first became boarded in 1995, she successfully recertified in 2005 and 2015. She is certified until 2025. The American Board of Veterinary Practitioners members must re-certify every 10 years to maintain their diplomate status. ABVP certifies veterinary practitioners with exceptional knowledge, skill, and competency in the care of the total patient. ABVP Diplomates are certified in clinical practice for the species in which certification is granted. Most veterinarians performing broad-based clinical practice are not board certified. The ABVP board certified veterinarian has demonstrated they are capable of providing a level of clinical practice.

Drs. Gayle Leith and Tresha Robinson also practice equine sports medicine in the field. Much of the equipment used to diagnose and treat sports related injuries is kept in the hospital, but Drs. Leith and Robinson are adept at determining if cases can be diagnosed and treated in the field, or if they need to come into the clinic.

So, as you can see, Arizona Equine is very well staffed with exceptionally skilled veterinarians that have close to 100 years combined experience in equine sports medicine. This is only a portion of the puzzle, however. The other vital part of equine sports medicine is diagnostic imaging.

In the middle of the 20th century, technology to diagnose and treat equine sports related injuries was almost non-existent. Since the 1970’s there have been amazing advances in technology that have resulted in many new diagnostic imaging tools used in the equine athlete. Arizona Equine has aggressively invested in these tools and will continue to do so. A description of some of these tools and their usage in equine sports medicine follows:

Physical Examination

This tool is one of the oldest used in equine sports medicine, probably dating back to the first cave-man that tried to determine why his horse was lame! We can’t over-estimate the importance of this tool. Many horse owners have heard the term “Dr. X” is a great leg-man (or woman)”. What this means is that this veterinarian is skilled in detecting problems in the sport horse just by a physical examination. Some of this skill can be taught, but in the case of most veterinarians, it a skill honed by years of experience. Our specialists have gone through this process and most of them have 20-30 years of experience in diagnosing and treating equine sports injuries. They have also had the added advantage of being able to confirm the results of their exams with advanced diagnostic equipment such as that listed below. This is extremely important, as it allows the doctor to confirm without a doubt that what they observed on the physical examination was what was truly wrong.

Radiography (x-rays)

Radiography has been in use in horses since the mid 1950’s, but technological advances allowed for the development of digital radiography over the past 10 years. Digital radiography has many advantages over analog (film) radiography, including increased detail; the ability to lighten, darken, or change the contrast of the image afterwards; the ability to transfer the images over the internet; the ability to store the images cheaply forever; the ability to observe the image almost instantaneously; as well as other advantages. Arizona Equine has digital systems in the hospital that allow us to obtain radiographic images of any part of the horse, including areas such as the abdomen or the back. We also have a portable digital system that allows us to take superb images of the legs in the field. The correct interpretation of the images is of paramount concern. Great images that are interpreted wrongly are no better than poor images. Our sports medicine specialists have extensive training in the interpretation of radiographs and provide correct interpretations along with great quality radiographs.


In this imaging modality, ultrasound waves are used to show the structure of soft tissues, including areas commonly injured in athletic horses. Tendons, ligaments, muscles, and joints are some of the areas that ultrasound is used to image in sport horses. Ultrasonography has been used since the 1970’s in horses, but, like radiography, recent advances in technology have vastly improved the quality of the images over the past 10 years. We have invested in ultrasound equipment that allows us to obtain the best images available from any clinic. This is another area in which our specialists have advanced training in interpretation of images.

Nuclear Scintigraphy

Nuclear scintigraphy is an imaging modality commonly referred to as a “bone scan”. A bone scan is a series of images obtained after injecting a very small amount of radiation into the horse’s vein. A simple explanation for how it works is that the radiation is distributed throughout the horse’s body by the blood system. Areas of inflammation have more blood going to them than do areas that are not inflamed, which is why inflamed areas are hot and swollen. Many times the inflammation is in an area that we can’t touch or feel easily (Inside a bone, or in the hip region, for example) so we have a difficult time identifying where it is located.

Since horses can’t talk and tell us where they hurt, or where they are inflamed, we need another way to determine the location of the injury. This is where a bone scan comes in. It is a very sensitive indicator of where inflammation is located. A bone scan can pick up inflammation that doesn’t show up in an x-ray or ultrasound for months or years, if ever.

The specifics of how this test works is as follows: The radioactive isotope (the substance that is injected) gives off gamma rays (a form of radiation) that are detected by our machine. If there are more gamma rays coming from a certain area of the horse’s body, then there is more radioactive isotope in that area, which means that area is inflamed.

A bone scan is very safe because of the tiny amount of radiation used. The radiation is essentially gone from the horse after 24 hours, so we are required by law to keep the horse until the day after the bone scan so that there is no chance of a person being exposed to it.

There are several advantages to Nuclear Scintigraphy: We can examine the entire horse in about 2 hours from when we start the scan, so it is a great screening tool when we don’t know where a horse hurts; It is the most sensitive indicator of inflammation that we have available, so it shows areas of inflammation that we can’t find any other way; It is very safe, as the radiation used is very small; It can be done standing; Results are available by the morning after the scan before the horse leaves; Everything is digital, so images can be sent over the internet.

There are several limitations of Nuclear Scintigraphy: The horse must stay overnight by state law; it is a day-long procedure overall (it takes 2 hours for the isotope to be delivered, then we wait to scan until 2 hours after the injection, and the scan takes 1-2 hours depending on what we scan); the scan is better at picking up bone problems than it is for soft tissue problems.

In summary, for cases in which we have problems determining where the horse hurts, a bone scan is the ideal diagnostic test.

Magnetic Resonance Imaging (MRI)

MRI is a well-known imaging test to most people because of its common use in human medicine. Unless you are a physicist, you probably don’t want to know how this test works! Basically a magnetic field aligns the hydrogen atoms in tissue and these atoms give off radiofrequency (RF) waves in response to changes in the magnetic field and the application of other RF energy to the system. The machine detects the RF waves given off by the hydrogen atoms and creates an image of the tissues. I warned you! Luckily, we don’t have to understand all of the details of how it works to use the machine and get good images!

While a bone scan allows us to image the entire horse to find out where it hurts (screening tool), an MRI gives us the best detail of a small area of the patient that is available today. Therefore, MRI is best used when we know (within 5-8 inches) where the pain is coming from.

There are several fundamental properties of MRI that determine when our specialists use MRI, and why we use the MRI system that we use:

1) Resolution: What do we mean by “resolution”? In layman’s terms, this means how clearly we can see the structure of the area we are examining. For each imaging test that we use, how clearly we are able to see is determined by the resolution of the image that results.

Resolution is how close two objects have to be for a person to tell that there are two objects and not one. Imagine you are driving on a desert road and a forest is in the distance. When you are 10 miles away you can’t tell one tree from another, so you have poor resolution (your eyes can’t see separate trees). When you are 1 mile from the forest you have better resolution. You can see that there are some large trees that are separate from each other, but you can’t tell if there are any smaller trees there. When you are entering the forest, you have great resolution. You can see not only separate small trees, but also separate bushes and other plants.

Now imagine that your horse has torn a ligament in his fetlock (ankle). If the tear is really large (say it’s 1/2 inch in diameter), then we can see the tear with an ultrasound machine. We don’t need an MRI, as it won’t help us any more than an ultrasound. If the tear is 1/32nd of an inch in diameter, we can’t see it with an ultrasound, but it would be very clear on an MRI. For soft tissues, MRI has MUCH better resolution than does ultrasound, radiographs, or a bone scan. We use MRI when we need better resolution.

2) Can the MRI be done standing? In 2005 Arizona Equine was one of the first clinics in the United States to purchase a novel MRI machine designed specifically for use in the standing horse (Hallmarq system). This machine was designed by an engineer in Great Britain because he could not understand why his horse had to be anesthetized to obtain an MRI of its feet. You can find details of this system here: http://www.hallmarq.net/. This is the only system in the world that allows images of the feet of the horse to be obtained standing. Hallmarq has won numerous awards for innovation. In 2015 Hallmarq was awarded “The Queen’s Award For Enterprise” by the British Royalty for its work to help horses. We are proud to be partners with Hallmarq, as they have helped horses immeasurably with their products.

Theoretically, areas higher up the leg can also be obtained standing, but the resolution suffers somewhat due to patient motion. At Arizona Equine we want the best images possible, so for scans of areas including the fetlock and above, we use general anesthesia. About 95% of our MRI scans are done standing, because most of the problems causing lameness in the horse are below the fetlock.

3) Magnet size of the MRI machine: As the size of the MRI magnet increases, the resolution of the image gets better. The physicist’s reasons for this are beyond this discussion. So the best system is the one with the biggest magnet, right? Not necessarily! To understand why, we’ll talk about the differences:

There are two broad categories of MRI machines based on the size of the magnet: High Field and Low field. High field magnets are those that have ratings of 1-2 T. T is short for Tesla, which is a unit of magnetic strength. The bigger the number is, the stronger the magnetic strength. Low Field magnets are generally considered to be those of 0.2-0.5 T. Currently there are two MRI machines in Arizona and both are low field magnets. The closest high field magnets are in Santa Barbara, California and Fort Collins, Colorado.

Why didn’t the clinics in Arizona put in high field magnets if the resolution is better? We can only speak for Arizona Equine, but for us it came down to how much resolution do we need, and can we do the scans standing? Before buying this system we met with several veterinary radiologists and each of them told us that the low field magnets will produce exceptional images, and that any problem that creates lameness in a horse should be visible on this machine. We have found this to be true over the last 10 years.

We like the analogy of television. If you are a fan of “Dancing With the Stars”, do you need an HD or 4K television set to determine who is the best dancer? No! You can tell who the best dancer is with a regular TV, even though an HD or 4K TV image looks prettier. The same is true with MRI. We want enough resolution to see the problem, but don’t need more if it requires general anesthesia.

The second consideration was whether we could do the scans standing, and this is not possible with any high field machine, or with any low field machine other than the Hallmarq system. This is why we have a low-field Hallmarq system.

Treatments Options

Once our specialists use all of their bright, shiny toys to determine where your equine athlete’s problem is located, what can they do about it? This is, after all, the most important thing to the owner.

Targeted therapy is of the utmost importance. If we can treat exactly what is wrong and nothing else, then we have a better chance of helping your horse recover. What types of targeted therapies are there?

1) Injection of medications: There are a number of medications that can help relieve inflammation and stop the pain associated with certain lameness conditions.

One of the most commonly used is corticosteroid injections into joints (steroid injections). Corticosteroids are a class of very potent anti-inflammatory drugs that not only relieve pain, but interrupt harmful negative cycles that can cause more joint problems if left untreated. There are several different kinds of corticosteroids that are used in different circumstances. The specialists at Arizona Equine are skilled at using the correct one to get your equine athlete back to work.

Hyaluronic acid is another drug that is commonly injected into joints to help relieve pain and inflammation and to speed healing. Many times it is used in conjunction with corticosteroids for optimal results. Hyaluronic acid is a natural substance that is found in healthy joints; it is a very slippery substance to the touch. It is called a boundary lubricant because it helps the joint tissues slide across one another easily. It also helps prevent harmful inflammatory substances from entering the joint, which reduces continued joint inflammation. The injectable form was originally extracted from rooster combs, but it is now produced in the laboratory.

Bisphosphonates are a class of drug that helps to prevent abnormal bone loss. Arizona Equine was one of about 20 equine clinics nationwide (and the only one in Arizona) to test the first bisphosphonate drug for FDA approval in the United States – Tildren. We found that it was safe and helpful in treating several equine problems. This type of drug has been used in horses in Europe for the last 20 years with good results in treating navicular disease and hock arthritis.

In some pathologic disease processes the horse’s body responds to inflammation by removing too much bone from a given area (navicular bone as an example). This can be detrimental in the long term, and can create a negative cycle that leads to permanent lameness. Tildren, or drugs like it, can interrupt this cycle and stop the bone loss. As a result of the study that we participated in, these drugs are now FDA approved and available in the United States for treating certain equine lameness conditions. Os-Phos is another bisphosphonate that is also on the market and is commonly used in horses.

There are other medications that are used for specialized problems, such as back pain. Sarapin is a drug that is derived from the pitcher plant. Purified forms are used to help relieve back pain, in conjunction with corticosteroids. Other medications are developed from time to time to help treat equine sports injuries. The veterinarians at Arizona Equine evaluate these as they become available and use them when it is shown that they are safe and helpful.

2) Regenerative therapies are a class of treatments that have been developed over the last 10 years, and are showing a lot of promise. These treatments revolve around using substances from the horse’s body that the body uses to heal itself. We collect these substances from your horse, and after concentrating them or enhancing them, we inject them into the area that is injured.

IRAP is a substance that is normally present in the horse’s joint. We can concentrate it from the blood and inject it into the joint to help relieve inflammation. It attaches to certain receptors in the joint that cause inflammation and block them from being used to create inflammation. This was used routinely 10 years ago, but has slowly fallen out of favor as better treatments have been developed. We still occasionally use this treatment for very specific cases.

PRP is short for Platelet Rich Plasma. Platelets are particles in the bloodstream that allow the blood to clot. They also contain a number of growth factors that help the body heal after injury. In order to use them therapeutically, they must be concentrated for injection. There are a number of ways to do this, but we use a centrifuge to spin down the patient’s blood. After spinning the blood for 15 minutes or so at 2400 rpm’s, we are able to collect the portion that contains the platelets. We then inject this into tendon or ligament injuries to help speed the healing process. We are also using this treatment in some joint conditions as well. We have had some great results with this treatment and it is one of our front line therapies for tendon and ligament injuries.

Stem Cell therapy is also an exciting treatment that has been developed recently. Stem cells are cells found in the tissues that are “precursor cells”. Precursor cells are very young cells that are able to transform into a large number of different types of specialized cells. For example, a stem cell can turn into a tendon cell if needed; or a blood cell; or a bone cell; or a neurologic cell. There is a lot of research going on into the use of these cells to heal human and animal disease. In the horse, there are several ways of collecting these cells for use therapeutically: Fat collection; Bone marrow collection; or using stem cells that have been harvested from mare’s placental membranes (embryonic stem cells). We have used stem cells in both joints and soft tissue problems (tendon and ligaments). Stem cell therapy can be very expensive, so the specialists at Arizona Equine will guide you to use it only in cases where we are certain that its use provides a benefit that justifies the expense. Stem cells don’t help every condition, and it is important to be discriminating in their use.

3) Shockwave therapy is a treatment that uses a certain wavelength of ultrasonic sound waves to stimulate healing and pain relief in certain tissues. The most advantageous shockwave therapy is “focused”. These shockwaves are produced by certain shockwave machines and create waves that go to a certain depth in the tissues and release their energy. This energy release stimulates the tissues in that area to bring in more blood supply to enhance healing. The energy release also deadens some of the nerves for a period of time to relieve pain. We have found shockwave therapy useful in treating tendon and ligament injuries as well as some back and neck problems.

4) Acupuncture is an adjunctive therapy that is used to stimulate healing and relieve inflammation. Dr. Tresha Robinson is certified in acupuncture and uses it in a variety of cases to help enhance the healing process. She would be happy to discuss its use in your particular horse’s case.

5) Chiropractic, massage, and body work is also an adjunctive therapy that may help in some equine athletic problems. While we don’t maintain a chiropractor or massage therapist on staff, we work with a number of them across the state and guide our clients and patients on when these treatments are indicated for certain conditions.

6) Rest or controlled exercise, while listed last, is extremely important in the treatment of many equine sports medicine injuries. The goal for most of our clients is the long term soundness of their equine athletes. While many of our treatments can speed the healing of our patients, they can’t magically replace the body’s healing process. This healing process takes a certain amount of time. The body’s healing process sometimes requires complete rest, but sometimes is better accomplished with a reduced level of work. The specialists at Arizona Equine can guide you to the appropriate amount of rest or work that is ideal for the long term success of your equine athlete.

In summary, Arizona Equine has you covered for any equine sports medicine problem that you may have. If you have any questions, or would like to discuss a case, give us a call!