Uses of Equine Ultrasound are Many—and Growing
Everything from looking at the throat to imaging the limbs, lungs and abdomen, can be imaged with ultrasound.
Anthony Pease, DVM, MS, Dipl. ACVR, sees virtually no limitations in the field of equine ultrasound.
“The sky is the limit. From looking at the throat to imaging the limbs, lungs and abdomen, everything can be imaged with ultrasound,” said Dr. Pease, an assistant professor of radiology in the departments of Small and Large Animal Clinical Sciences at Michigan State University’s College of Veterinary Medicine.
Other uses, said Pease, who will begin a one-year term as president of the American College of Veterinary Radiology beginning in 2014, include a technique he created at MSU to sample spinal fluid in the standing horse using ultrasound guidance to look for neurologic disease.
Pease and other practitioners spoke enthusiastically about the numerous possibilities for ultrasound in equine medicine.
“Ultrasound can evaluate soft tissue and even look for fractures that cannot be imaged with radiographs, such as pelvic fractures,” Pease said. “You can even perform internal ultrasound transrectally to look at the sacroiliac joints, intestines, uterus, ovaries, kidneys and spleen. You can look for fluid in the abdomen to help with diagnosis of abdominal or thoracic disease.
“I guess in short, I cannot say enough about how useful ultrasound is in aiding in diagnoses of disease.”
Ask Carol Gillis, DVM, Ph.D., Dipl. ACVSMR, with Equine Ultrasound and Sports Medicine in Aiken, S.C., if more aliments are being diagnosed with ultrasound nowadays, and you’ll get a resounding “yes.”
“Yes, firstly because more veterinarians are thinking of using the modality to investigate the status of more different structures, and secondly because image quality and ease of use of ultrasound equipment improve annually,” Dr. Gillis said.
“Diagnostic ultrasound is safe, relatively inexpensive, provides detailed information about the internal architecture of structures examined and can be accurately repeated. No general anesthesia is required, which saves a major expense and risk to the health of the patient.”
One of the best applications in equine medicine is musculoskeletal ultrasound, the use of sequential imaging to follow healing so that controlled exercise can be accurately implemented, Gillis said.
She offered a list of best uses for musculoskeletal ultrasound:
“TM (temporomandibular joint); neck shoulder joint and associated tendons; ligaments and muscles; forearm and forelimb joint and soft tissue; foot soft tissues; withers; back joints; spine and associated muscles and ligaments; croup muscles; spine and ligaments; hip joint, stifle, femur, tibia and hindlimb bones; joints and soft tissues.”
MSU’s Pease believes that by far the best application is in the acute equine abdomen.
“I use ultrasound almost every day to diagnose and treat lameness problems in my patients. It is an excellent tool for diagnosing soft tissue injuries and it allows for safer and more accurate injection techniques in many areas of the body.”
“An ultrasound machine is the single most useful tool for an equine veterinarian. Aside from the many uses in reproduction and lameness, it is invaluable in evaluating virtually endless soft tissue problems, and even bone surfaces. From locating abscesses, muscle tears, etc., to evaluating the character of various lumps and bumps, it would be the instrument I’d least want to part with.”
“Recently new information on the equine G.I. tract and ultrasound imaging has allowed much better assessment of abdominal issues.”
“Ultrasound is an important diagnostic modality for orthopedic injuries, particularly the axial skeleton, which at this point cannot be evaluated with MRI or CT, acute and chronic colics and reproductive medicine.”
“The sky is the limit. From looking at the throat to imaging the limbs, lungs and abdomen, everything can be imaged with ultrasound.”
“Horses with colic or acute abdominal pain are very difficult to treat and if the lesion requires surgery, then time is of the essence,” Pease said. “Survival is directly correlated to the time of surgery and the sooner the decision is made to go to surgery and get them to a referral hospital, the better the chance for survival.”
Pease also noted that chronic lameness can be evaluated using ultrasound, and when used in conjunction with radiographs, may provide a method not just to identify a cause, but to evaluate treatment.
Heather Beach, DVM, with Connecticut Equine Clinic in Coventry, Conn., takes advantage of the portability of the ultrasound machine to deal with emergency situations, and routinely uses it to assess the abdomen in complicated colic cases, or to determine what structures are involved in a serious wound.
“The ultrasound can be an extension of the physical exam in the hands of a skilled user, and it enables me to be very precise with my workups in the field,” Beach said. “Sometimes I am able to fully appreciate the extent of an injury or illness and other times I see an indication that the horse needs to be referred for further treatment or diagnostics.”
Like others, J.K. Waldsmith, DVM, president of Vetel Diagnostics and owner of The Equine Center, a full-service hospital, in San Luis Obispo, Calif., can rattle off a list of ultrasound’s best applications.
“Ultrasound-guided procedures—stem cell injections, joint injections, nerves, etc.; reproduction; musculoskeletal disease,” were the first on the list he offered. “Recently, new information on the equine G.I. tract and ultrasound imaging has allowed much better assessment of abdominal issues.”
Orthopedic injuries top the list of uses for Myra Barrett, DVM, MS, Dipl. ACVR, assistant professor of radiology at Colorado State University.
“Ultrasound is an important diagnostic modality for orthopedic injuries, particularly the axial skeleton, which at this point cannot be evaluated with MRI or CT; acute and chronic colics; and reproductive medicine,” Dr. Barrett said.
Barrett believes orthopedic uses are at the forefront of breakthroughs in the field.
“There have been a lot of advances in orthopedic imaging by including more on- and off-angle imaging and non-weight-bearing imaging,” Barrett said, adding that elastography, fusion imaging and contrast-enhanced imaging are all growing in use or are being investigated for use in equine ultrasound.
Waldsmith believes one of the biggest breakthroughs in the field came with the introduction of sound speed corrected systems.
“They greatly speed up work flow, and the image quality is substantially better,” Waldsmith said.
He also is a fan of picture archiving and communications systems, or PACS, which provide economical storage of images from multiple modalities.
“The big thing is the movement of the measurements to PACS systems, where the information is better integrated with other imaging modalities,” Waldsmith said.
Ultrasound has been around for a long time, more than 30 years by Pease of MSU’s account, so the technology has improved a great deal.
But Pease feels the most exciting advancement is the use of ultrasound to acquire spinal fluid in the standing horse.
“Equine protozoal myeloencephalitis (EPM) is a chronic neurologic condition that is difficult to diagnose without spinal fluid,” Pease said. “In addition, new technologies like elastography are being researched to evaluate tendons to see if micro damage can be detected prior to a complete tear. Imaging horses is very necessary because they are super athletes that will run and exert themselves until damaging or hurting themselves.
“Veterinary medicine is changing from a specialty that treats disease to focusing more on preventive medicine and protecting the patients.”
Where’s the field headed?
“Equine ultrasound is a non-invasive, very accessible way to assess tendon and joint lesions, reproductive status and gastrointestinal disorders,” Pease said. “Although extensive training is required, the usefulness of this technique is remarkable and with the help of training from board certified radiologists, this technique can be mastered and aid in rapid diagnosis of a variety of diseases.”
The only limits Pease sees is lack of training.
“Technology is always improving and ultrasound is very good at measurements, much better from year to year,” Pease said.
“The main limitation is the person performing the ultrasound examination. Ultrasound is like using a laser pointer to look around a dark room. You can create artifacts that look like lesions and miss lesions if you are not thorough enough. Training is very important, as well as maintaining training because the machine is only as good as the person using it.”