Having reported on veterinary conferences for nearly 40 years, I have seen many groundbreaking technologies and research results shape the equine industry. Even among all of those decades of change, the recent AAEP Summer Focus meeting offered some amazing shifts in the way that equine veterinarians think of lame horses and offer help to those animals.
The meeting, held at Colorado State University (CSU), provided a wide variety of research-based knowledge and hands-on skills. But perhaps the top sentiment that stuck with me and others at the conference was that the veterinary industry needs to help horse owners first look for physical problems that cause “misbehavior” in horses before they label a horse as “bad.” And there is a wealth of new and emerging technologies and diagnoses available to veterinarians to make that investigation and treatment better than it ever has been.
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The other shift in thinking is to view the lame/neurologic horse as an athlete that needs physical therapy, focusing on exercises adapted for that individual animal. That might mean horses are receiving months of core/balance strengthening, passive or active therapy, and an array of sports medicine techniques that heretofore have been reserved for elite human athletes.
The majority of attendees at the 2019 summer AAEP Focus meeting participated in the sports medication lectures and wet labs, which we will cover in this article. Others partook of ophthalmology lectures and labs. All of the attendees enjoyed CSU’s state-of-the-art facilities for lectures and labs, as well as access to the CSU faculty as speakers.
Fourteen presenters discussed topics ranging from “Fact Finding: History, Physical Exam” and “Diagnostic Analgesia” to “Managing Horses under USEF and FEI Rules.”
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Melissa R. King, DVM, PhD, DACVSMR, focuses on the study and application of equine rehabilitation at CSU. King’s current research interests involve the objective assessment of various rehabilitation modalities and therapeutic exercises for the management of equine musculoskeletal injuries, as well as the biomechanical assessment of compensatory gait adaptations.
She discussed a variety of physical therapies and rehab protocols, but first stressed that a veterinarian must reach “an accurate diagnosis followed by establishing clearly defined rehabilitation goals that consider the biomechanical implications of the original injury. The most effective rehabilitation programs utilize regular, longitudinal patient assessments, followed by appropriate adaptation of protocols with both injury-specific and whole-body considerations.”
One area she discussed was thermal (heat and cold) therapy. “Thermal therapy consisting of cryotherapy, heat therapy or a combination thereof (contrast therapy) remains a fundamental cornerstone of many physical therapy programs,” she noted.
The therapeutic effects of cold therapy in people are generated through reducing tissue temperatures to 10° to 15°C, she noted. “Tissue cooling produces peripheral vasoconstriction and decreased soft tissue perfusion, which can reduce edema formation and swelling at the site of tissue injury. Cold therapy also mitigates tissue metabolism and apoptosis, and decreases the release of inffammatory mediators and abates local enzymatic activity.”
She said the application of cold also serves as a form of pain modulation by “decreasing nerve conduction velocities in local sensory neurons and by activating descending inhibitory pathways.”
She noted that cold therapies can penetrate up to 1-4 cm in depth, which is dependent on local circulation and adipose tissue thickness. “Human studies have documented the analgesic benefits of cryotherapy with a 15-20 minute application providing pain relief for one to two hours,” King said. “In horses, ice water immersion for 30 minutes reduced the superficial and subcutaneous tissues in the distal limb to within optimal therapeutic range compared to cold pack application.
“Application of a compression boot with continuous circulating coolant applied to the distal forelimb of horses for one hour significantly reduced the SDFT core temperature to 10°C,” she added.
King noted that cryotherapy research in horses has focused primarily on applications within the distal limbs and on inflammatory responses associated with laminitis. “The exact effect of cryotherapy on various equine musculoskeletal injuries has not been fully elucidated,” she said.
King said that cold therapy is indicated in “acute musculoskeletal injuries and following surgical procedures to reduce edema, slow the inflammatory response and reduce pain. It is particularly effective during the first 24 to 48 hours after injury or surgery.”
She said that the average time of cold application is 20 to 30 minutes.
“Treatments are best repeated every two to three hours during the first 48 hours following injury or surgery,” noted King. “Ice may be placed in a plastic bag or water may be frozen in a paper cup and applied to the site of injury.
“Cryotherapy may be indicated for up to 10-14 days post injury, depending on the severity and type of injury,” she continued. “A general rule of thumb for monitoring the need for continued cryotherapy is that the affected tissue should return to normal regional tissue temperatures and no longer have any signs of heat and swelling.”
Chiropractic and Acupuncture as Diagnostic Tools
Kevin K. Haussler, DVM, DC, PhD, DACVSMR, an associate professor at the Equine Orthopaedic Research Center at CSU, is involved in research into the objective assessment of pain, spinal-related disorders and the initiation of chiropractic and physical therapy/rehabilitation research for the management of musculoskeletal injuries.
As the summary for his presentation, Haussler noted that “equine sports medicine practitioners are often presented with horses that have vague signs of reduced performance or poorly localized lameness related to athletic pursuits. Chiropractic evaluation can provide tools to identify and localize subtle soft tissue injuries, joint stiffness and musculoskeletal pain. Acupuncture evaluation can help provide insights into pain mechanisms related to primary or compensatory lameness issues.”
Because sporthorses undergo chronic, repetitive stresses associated with athletic performance, poor performance is a common clinical complaint in that group of animals, said Haussler. But “not all lameness issues are readily localized to the distal limb.” He said there is a heightened awareness of the role of chiropractic and acupuncture in the diagnosis of poor performance in horses.
He said that poor performance might be a vague lameness, an altered gait, or involve trying to determine whether the horse is lame or neurologic.
“Pain and fear drive horses,” said Haussler. “If a horse is ‘grumpy’ or unhappy, look for pain.”
“Chiropractic and acupuncture offer detailed spinal evaluation techniques of the neck, withers, back, pelvis and for overall stiffness,” noted Haussler. “And you have unique treatment options that are conservative, drug-free approaches to treatment while offering individualized patient care.”
Back Issues in Horses: Back problems in horses are a common but poorly understood clinical entity, said Haussler. Prevalence varies from 13-94% depending on the examiner, and a definitive diagnosis and positive outcome are often difficult due to:
- vague or complex clinical signs;
- limited objective measures;
- good pathological reports; and
- limited proven effective treatment options.
Haussler said there are “gray zones” where a horse has an altered or asymmetric gait, but the practitioner doesn’t know which it is, or if it is a combination of both. “Treating the limbs might not fix whole horse,” he stressed.
Haussler said it has been reported that approximately 30% of horses with lameness have concurrent back pain. Conversely, in horses with documented back or sacroiliac pain, approximately 70% also have a concurrent fore or hind limb lameness.
He also reminded the audience that older horses are susceptible to loss of spinal flexibility, joint degeneration and loss of muscle strength. “Aged horses also have increased healing times and increased chances of having chronic conditions or abnormal musculoskeletal compensations from prior injuries,” he noted.
Therefore, when equine veterinarians are dealing with sporthorses, a full lameness exam should include a back/ spinal exam. Hausser said there is a difference in acute back pain (a horse being sore from overuse) and chronic pain (a horse may have neuropathic pain that is not readily localized and not amenable to anti-inflammatories). In the latter horse, he said acupuncture is useful.
Haussler said a sports medicine practitioner’s list of modalities includes:
- therapeutic exercise;
- physical modalities;
- manual therapies; and
- patient education.
When discussing specific evaluation techniques, Haussler had some great videos of equine patients to illustrate his points. If you have a chance to see a live presentation by Haussler or attend a hands-on lab with him, take advantage of the opportunity!
Fact Finding: History, Physical Exam and Diagnostic Analgesia
“Many equine vets spend most of their time dealing with lameness issues in horses,” said Christopher E. Kawcak, DVM, PhD, DACVS, DACVSMR, a professor of orthopedics at Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University. He stressed that there is a lack of consistency between examiners, procedures, interpretations and a finding’s relevance to performance in the equine athlete.
Kawcak is one of a team of researchers working to find ways to prevent and treat catastrophic injuries in equine athletes. He is assessing three-dimensional imaging techniques, MRI and CT to diagnose early joint disease and microscopic joint injuries before these develop into serious injuries. Working with researchers in biomedical engineering, his team has developed biomechanical models to assess risk factors specific to each individual athlete with implications for human bone and joint disease.
Kawcak discussed how the history of the horse can help a veterinarian formulate a plan for characterization of the problem, as well as how veterinarians can:
- identify the most objective changes in horse’s gait during a lameness exam;
- use clinical tools to characterize a horse’s lameness; and
- develop strategies for dealing with the lame horse.
Hurt vs. Injured: Kawcak talked about how most great human athletes play with pain or dysfunction. However, he noted that human athletes have a choice to play with those challenges, while a lame horse evokes an emotional response that brings in the topic of welfare. He talked about the recent Equine Veterinary Journal debate that centered on whether a lame horse is unfit to perform, which equals a welfare issue.
Kawcak said that when you define lameness, you need to decide whether it is a pathologic disorder or clinical sign in that horse. He said you also need to consider whether a gait asymmetry is a true lameness. He said that it is essential to understand that “lameness examination is an artistic experience acquired by years of clinical practice along with integration of the objective information to best characterize the problem.”
Kawcak talked about the need to better understand subtle gait alterations and to put them into context of “normal variation” rather than lameness. For example: What level of musculoskeletal pain is expected from a horse in training or one that is ready to compete?
He talked about the fact that FEI horses have subjective and objective lameness evaluations because that group of horses has a high incidence of lameness. He said multiple limb lamenesses are common in those elite athletes.
There also is the public welfare concern of bone fatigue and its implications for injuries in racehorses. Kawcak said that before bone breaks apart, there is remodeling and microdamage. “There is growing evidence that there is fatigue injury in muscle, tendon, bone and cartilage,” he said.
He talked about the development of an ethogram for a pain scoring system in ridden horses and its application to determine the presence of musculoskeletal pain. The pain ethogram was researched by Dr. Sue Dyson and published in the Journal of Veterinary Behavior. Dyson, Head of Clinical Orthopaedics at the Centre for Equine Studies at the Animal Health Trust in Newmarket, found that there were 24 behavioral markers that were most consistent in the lame horse. Dyson tested these markers with veterinarians, who reported that they were beneficial in lameness evaluation.
History of the Horse: Kawcak said that although some vets wait until after an exam to ask for the horse’s history from the owner or trainer, “I like to get history before exam.” Included in the history is the use and level of competition, rider experience, previous lameness(es) and treatment(s), and characteristics of the lameness.
He noted that vets need to understand the influence of rest on lameness. “Research in racehorses has shown that there is an increased risk of fracture 121-214 days after a 60-day rest period,” he said. Kawcak noted that the type of injury correlates with osteoclastic bone resorption out-pacing bone formation, which you can mitigate with short periods of work during the rest period.
Lameness Exams: While Kawcak in his lecture went into the examination of the horse very specifically, below we will just note some of the highlights of his talk.
Separate hands-on labs that allowed veterinarians to learn different or additional palpation techniques were one of the highlights of the meeting, according to some attendees. They said they couldn’t wait to go home to practice and apply what they had learned to their clients’ horses.
In one lab, Haussler focused on palpation skills with his small group of veterinarians (at their request). He recommended that during the observation stage, veterinarians create pre-formed ideas of whether the horse will be stiff, painful or both, then see how well their pre-formed ideas hold up after their exams.
Haussler recommended that veterinarians look at conformation, posture, hair, epidermis, dermis/fascia and muscles—then use boney palpation. He demonstrated several specific palpation techniques and individually instructed the veterinarians to help them gain experience.
Melinda R. Story, DVM, DACVS, DACVSMR, cVMA, cIVCA, suggested that veterinarians start any lameness evaluation with a myofascial exam of the horse. “If you think something is going on, don’t touch the horse, but get really close and feel for heat,” she suggested.
Summary on Lameness Exams: “Where do I start?” Kawcak asked the audience. “I have found that going right to advanced imaging actually saved my client money in the long run in some cases,” he said.
What constitutes an adequate exam? Including owner/rider/trainer insights; basic lameness exam; responses to flexions; basic blocks.
“The goal is to reduce the risk for further injury as much as possible,” Kawcak said. “Stay consistent, determined and disciplined in your exams. Use what is in literature, but read it carefully.”
The speed at which equine rehabilitation is progressing today is amazing. Items you might have seen or used yourself during physical therapy are now integrated into bringing the equine athlete—or even the beloved trail horse—back to fitness.
This article and "Tidbits from Other 2019 AAEP Summer Focus on Sport Horse Talks" are brought to you by Soft-Ride.