The 2019 AAEP Summer Focus meeting held at Colorado State University (CSU), provided a wide variety of research-based knowledge and hands-on skills. You can find a report on the meeting brought to you by Soft-Ride in the EquiManagement Winter 2019 magazine issue. Following is additional information from that AAEP Summer Focus meeting.
Equine Lameness Exams
Christopher E. Kawcak, DVM, PhD, DACVS, DACVSMR, a professor of orthopedics at Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences,CSU College of Veterinary Medicine and Biomedical Sciences, in his lecture noted that age is a factor in lameness, as is conformation. The following contains excerpts and summaries from Kawcak's lectures.
He said a conformation exam is the first step in evaluating lameness. “When you do a conformational examination, view the horse from all sides,” he said.
He also suggested that veterinarians assess the conformation of the horse in respect to the horse’s intended use.
The next phase is the static exam, or physical exam. This is where you get your hands on the horse to look for heat, pain, swelling and changes in architecture, such as muscle atrophy. “You are looking for geometry and pain,” he said.
Kawcak noted that some joints are hard to palpate, and that you need to recognize that a thickened joint capsule is different from effusion.
In soft tissue exams, you should look for geometry and pain; in bone you look for geometry, pain and possible impingement.
During range of motion exams, a reduction in range is not always pathologic, Kawcak said. “An old racehorse might not have a fetlock that flexes at all,” he noted.
He said that veterinarians should remember that some young horses in active work will respond “dramatically” to passive flexion, such as with the fetlock joint of Thoroughbreds and the hind limbs of Western performance horses.
“Isolated pain on palpation is of value for further investigation; however, for proximal suspensory ligaments, for example, there can be significant damage at the origin without much response to palpation,” noted Kawcak. “Conversely, significant pain can sometimes be elicited in the proximal suspensory area without significant damage. In the latter case, some have speculated that the pain response is due to stimulation of the adjacent nerves, or some also have speculated that foot or fetlock pain can change their way of going and also create pain in the suspensory body that is secondary to the real cause of pain.”
Kawcak said that hoof testers should be used, especially around the nail holes, sole, frog and the hoof wall. “However, care must be taken in remembering that hoof testers have been shown to be about 50% accurate when correlated with caudal heel pain,” he said. Examine the hoof capsule for conformation and coronary band characteristics, and look at the shoe for uneven wear.
The third phase of Kawcak’s lameness evaluation is the dynamic exam. During this phase, horses should be walked to evaluate coordination, hoof landing and limb movement. In addition, the stride length and the cranial and caudal phase of the stride should be characterized.
“A neurologic assessment should also be made during that same time,” he noted. “Most of the assessment of lame horses is done at a trot, and in North America, a 0-5 grading scale is used.”
The same types of tests can be done in circles, on various surfaces, up and down hills, on a lunge line, and following flexion. Kawcak said some consider flexion tests contentious. “They are sensitive, but lack specificity,” he said. “I don’t put 2- to 3-year-old reining/cutting horses in long flexion, because they will be sore.”
“You should break down the stride if you can,” said Kawcak. “Look at flexion and swing, impacting the ground, support and thrust.”
It is important to be as consistent as possible in your grading so that you—and other veterinarians you are communicating with—can relate knowledgeably to the notes you make about the horse.
Hind Limb Lameness
Hind limb lameness is where veterinarians and students struggle, noted Kawcak. “With hind limb lameness, the entire pelvis rises before the lame limb contacts the ground,” he said. “You most commonly see differences in hip motion with increased push-off from the sound limb at the end of the stride. In horses with more severe lesions—grade 3 and above—the head will often go forward, sometimes confusing this with forelimb lameness.”
Kawcak said there is an emerging and growing market for wearable technology use in horses, including for lameness evaluation. “Care must be taken when relying on such devices, as gait is a continuum in which a perceived ‘lameness’ might actually be the normal way of going for a particular horse,” he noted.
At a trot in hind-end lameness cases, the lame side typically shows a quicker drop at the end-of-contact phase of stride, said Kawcak.
When lunging horses, good control and consistent circles are necessary for a quality lameness exam, he said. Try to keep the person still in the middle of the circle to avoid inconsistencies.
“Foot pain will be worse on the inside of the circle and better on soft ground,” he said. “Soft tissue problems are often worse on the outside of the circle.”
He added that, “Induced lameness is not the same as clinical lameness. Induced forelimb lameness causes both a compensatory contralateral and an ipsilateral hind limb asymmetry, potentially mimicking a hind limb lameness, but of smaller magnitude.”
A riding exam is often necessary during lameness evaluations. “You can get a feel for how the horse is in its natural working environment,” said Kawcak.
He said a sitting trot or two-point position is better than a rising trot for lameness exams, according to research. Kawcak also discussed research on saddle slip and girth fit in relation to lameness. “Try changing the tack or girth and see if there is a difference in how the horse goes,” advised Kawcak.
Kawcak said that if a horse is worse after nerve blocks wear off, be concerned about a stress fracture.
“Blocking is an essential part of isolating the site(s) of pain,” said Kawcak. “The goal is to try to identify primary source of pain. But it is not uncommon to see secondary sites of pain such as PSL, neck and shoulder, or back.”