Thinking Outside the Box: Using Ultrasound on the Whole Horse

Learn about the countless ways to put ultrasound equipment to use in your practice.

The versatility, portability and accuracy of today’s ultrasound machine is hard to beat. Arnd Bronkhorst Photography

Ultrasound isn’t just for reproductive or hock-down musculoskeletal diagnostics in racehorses anymore. As the technology has evolved and image resolution has increased, ultrasound has become an invaluable tool for everything from lameness exams to tumor exploration to guided joint injections—and much more.

“Ambulatory practices that aren’t using the technology are hindering their ability to provide a complete diagnosis,” said Richard D. Mitchell, DVM, MRCVS, DACVSMR, of Fairfield Equine Associates in Newtown, Connecticut. He is certified in Equine Locomotor Pathology (through ISELP) and serves on the board of directors of the International Society of Equine Locomotor Pathology (ISELP).

At Mitchell’s practice, each of the seven veterinarians is equipped with a portable ultrasound machine. The staff veterinarians are expected to use the machine daily. But that’s not because the practice specializes in reproduction; the clinic focuses on the care and treatment of sporthorses.

“There are a wide range of services that can be provided with today’s ultrasound machines,” he said. “It has evolved far beyond the uses it had in reproductive practices.”

When ultrasound was introduced to the equine world in the late 1970s and early 1980s, it was strictly used in reproduction for pregnant mare checks to examine the ovaries and uterus. As the technology evolved, it was used on soft tissue injuries in the distal limbs in carpus/hock-down scenarios.

“Cardiologists started doing echocardiograms, and ultrasound was occasionally used on the horse’s chest to find evidence of fluid accumulation in pneumonia cases,” he said. “Then it evolved to use in the abdominal organs—the kidneys, bowel, spleen and so on—to determine the evidence of disease.”

Mitchell credits French veterinarian Jean Marie Denoix, DVM, PhD, Assoc. LA-ECVDI, DACVSMR, Certified in Equine Locomotor Pathology (ISELP), and the current president of ISELP, with transforming the role of ultrasound for sporthorse practitioner. Denoix is considered the world’s foremost equine musculoskeletal system anatomist, as well as a leading equine diagnostic ultrasonographer. His anatomical studies opened the door to investigating the distal limb, the stifle, the hip, back and neck with ultrasound equipment.

“Today, there are a wide diversity of issues that ultrasound is used for,” he said.

The average four-year veterinary program doesn’t provide in-depth training in ultrasound. However, a plethora of training is available after graduation. “If you understand the versatility of the ultrasound equipment, you will use it more often than an X-ray machine,” he said.

Whether you’re purchasing your first ultrasound machine or committed to increasing use of one you already own, read on to discover how to make the most of ultrasound in your practice.

Lameness Exams

For Mitchell and the veterinarians at Fairfield Equine Associates, ultrasound is a go-to tool for swollen or abnormal limbs tied to soft tissue issues.

“You’re not going to look at every fat leg the first time,” he said. “It may be an infection or a blunt-force trauma causing the swelling. But maybe the second visit warrants an ultrasound.”

Clients sometimes balk at the perceived cost of an ultrasound at the initial stage of a lameness exam. However, a clear diagnosis at the outset can save the client expenses over the long term.

“You can save the client more money by using ultrasound on the first visit rather than having to go back two or three times,” Mitchell said.

Including clients in the exam process increases buy-in. Mitchell encourages clients to watch over his shoulder during an exam. He explains what he is observing on the injured leg and points out where the injury is. Then he ultrasounds the normal limb as a control so that the client can understand what is going on.

“They love that, and it helps them understand what it will take for their horses to heal,” he explained.

Ultrasound isn’t limited to lameness diagnosis. It can follow the progression of healing. “Ultrasound can’t measure tendon strength, but you can follow fiber pattern,” he said. “Based on that, you can tell if the horse needs a longer lay-up period or if it is ready to begin building strength through another step in rehab and training.”

He acknowledged that X-rays are still the gold standard in distal limbs for osseous structures and the foot, but said that portable ultrasound machines are quickly gaining in popularity.

“Once veterinarians understands how to use the ultrasound, they will use it more than their X-ray machine,” he said.

Ultrasound-Guided Injections

Stifle injections are routine procedures for veterinarians working in practices that treat sport and performance horses. Despite having performed thousands of injections throughout his career, Mitchell sometimes uses ultrasound to guide his injections of the stifle and always uses the technology when injecting the sacroiliac.

“Using ultrasound is far more accurate than doing a blind injection,” he said.

With the proper probes and attachments, ultrasound-guided injections facilitate more accurate treatment in the joints, neck, back, hip and stifle. Prior to the development of ultrasound and its subsequent use in equine medicine, veterinarians were taught to diagnose lameness based on feeling the location, testing the hoof, blocking the nerves, using X-ray, then surmising what the issue was based on location. Then, when injections were used, veterinarians relied on palpation to find the joint.

“There are still veterinarians that say they can feel soft tissue abnormalities without ultrasound, and I don’t buy it,” he said. “If it is at all suspicious, it warrants a second look.”

The Whole Horse

Once veterinarians are confident with using the equipment, they will find that there isn’t much it can’t be used for. For example, it can be used to examine masses and lumps throughout the body.

“From an ultrasound image, we can determine if a lump on the neck is from an injection or is a tumor that needs aspiration,” he said.

The equipment’s portability makes it an ideal tool for exploring areas not practical with X-ray. Mitchell has used ultrasound on the horse’s head—specifically the temporomandibular joint, the eye and the larynx.

“Examination of an enlarged eye can help determine if the globe itself is abnormal or if perhaps there is a mass behind the eye,” he said. “The TMJ lends itself to examination for arthritis or meniscal damage, and techniques for laryngeal exams have been developed.

“We’ve been able to use ultrasound to determine if a horse has glaucoma, a tumor in the eye or a tumor behind the eye,” he said. “We’ve also used it on the larynx to determine muscle loss due to paralysis or other abnormalities.”

With special preparation, ultrasound is used to provide images through the underside of the hoof. “We pare away the bottom of a dry hoof, soak it in poultice overnight, then look through the hydrated portion of the frog to view the navicular bone and deep flexor tendon,” he said.

A key to using ultrasound successfully in non-traditional applications is investing in a variety of probes and attachments. “You have to have multiple probes to make the most of your investment,” he said.

Take-Home Message

There will always be a place for X-ray, MRI and computerized tomography (CT), but the versatility, portability and accuracy of today’s ultrasound machines is hard to beat. Ultrasound can be used to examine any unusual soft tissue thickening or musculoskeletal issue, especially in places such as the neck, front of shoulder, buttock, head and hip.

Purchasing a piece of ultrasound equipment is a sizeable investment that can range from $20,000 to $50,000. A good-quality machine with an assortment of extra probes can be purchased in the $23,000 to $35,000 range, Mitchell said.

“If the equipment is simple to use and portable, it will get utilized regularly, therefore providing a rapid return on investment,” he said.

He prefers standalone ultrasound machines, but he acknowledged that ultrasound attachments are available for laptops. Despite the laptop attachments that are available, Mitchell encouraged veterinarians to invest in standalone machines rather than computer add-ons.

Learning to use an ultrasound machine and understanding what the images are depicting can sometimes be intimidating. However, Mitchell pointed to the wealth of training that is available through ISLEP and other continuing education training providers.

Mitchell’s last word of advice on getting the most from your ultrasound is to put it in your practice vehicle. “If the machine is in the car, it will get used,” Mitchell said. “If it’s back at the practice, it will collect dust.” 

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