Diagnosing Horse lameness

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1 Diagnosing Horse lameness The 16-year-old Warmblood gelding had been performing successfully in upper-level dressage when he came up lame in his right hind leg. Two veterinarians examined him before narrowing the issue to the horse s front legs. The horse s hoof walls had separated in both feet, with severe coffin bone rotation in the right front. Such is the challenge when diagnosing many lamenesses. Is a horse limping because of a problem in that lower leg? Is he compensating for pain in another limb? Or does the lameness stem from further up in his body? No matter where the lameness originates, veterinarians maintain that owners are best situated to notice early changes. Many can sense when something is just beginning to go wrong, whether it s due to a barely noticeable difference in feel under saddle or even an uncharacteristic behavior in the stall. If you know what to look for, you can get veterinary help for your horse before the problem worsens. Here, in the first of this two-part lameness series, we will examine lower-limb problems how owners might notice them and veterinarians diagnose them. In part two we will examine lamenesses that occur due to body problems. Carrie Schlachter, VMD, and Kirste Timm, DVM, both focus on sport horse health and see a wide variety of lamenesses in their client populations. As the medical director and staff veterinarian of Circle Oak Equine, a practice centered around sports medicine and rehabilitation in Petaluma, Calif., Schlachter sees many horses referred to her for second or even third opinions or for advanced lameness diagnostics. Timm runs California Equine Sports Medicine, a solo ambulatory practice in Santa Ynez, Calif. In the aforementioned case, Schlachter conferred with the horse s primary veterinarian to discover the front-leg-lamenesses. This horse had been compensating for gradually increasing front foot pain for more than six months, says Schlachter. Since it wasn t an obvious, sudden

2 onset, it went unnoticed by the owner and trainer until he was no longer able to-compensate. The good news is that after months of rehab and therapeutic shoeing, the gelding returned to soundness and full work. Such can be the case when owners notice and report a problem and work closely with their farriers and veterinarians to determine a cause and treatment plan. The rule of lameness in the front end is down on sound, meaning the horse s head goes down when the sound leg is on the ground. DR. CARRIE SCHLACHTER Signs of Lameness Lameness does not always appear as a horse favoring a limb, though this tendency is certainly a strong indication that something s wrong. Lower-limb lamenesses can present with signs ranging from a change in attitude toward certain types of work, even trotting forward, to overt head bobbing and change in carriage to the whole body, Timm says. Schlachter advises owners to watch for any change in performance or behavior that could presage lameness. She cited examples of refusing to change leads or jump, running out at barrels, or misbehaving in the starting gate. Of course, these could also be signs of a horse not taking to his training or just being irritable on a particular day. But it s always a good idea to rule out an underlying injury or lameness first, especially when the horse has performed those tasks willingly in the past. Be vigilant for lameness signs, from the moment you walk into your horse s stall through your entire ride and into the-cooling-out and putting-up routines.

3 The owner and trainer are the first line of defense, says Schlachter, coupled with any body workers (grooms, chiropractors, massage therapists, etc.) who see the horse regularly. They are the experts on normal for this horse. They can direct the veterinarian toward what the horse is doing that is abnormal. If you feel something not right while riding, Timm says to dismount and examine the limb for heat, swelling, or wounds, and to check for dirt, rocks, or foreign objects packed in the foot. Once the horse cools down, adds Schlachter, check his temperature and see that he is eating, drinking, and defecating normally. A reason for lameness might be evident immediately a sole bruise, for instance, can be particularly visible on a white foot. Your farrier can identify less conspicuous bruises and abscesses while trimming the foot. Schlachter suggests that if you and your farrier can t find an obvious issue, ride him again at the walk, trot, and perhaps canter, but without-upper-level movements, to see if the problem improves or worsens. Solicit a friend or trainer to observe how the horse moves with you on his back, says Timm. Does he favor a particular limb when you ride him on a straight line? Does the lameness worsen in a circle and, if so, in a particular direction? Determine whether the lameness is noticeable without a rider. Armed with these details, Schlachter says, call your veterinarian and determine next steps. He or she will ask questions, first to determine if the situation requires an emergency visit, such as with laminitis signs or a penetrating wound, or if it can be assessed in a scheduled visit. But what about a vague lameness where you can t see an obvious cause and the horse does not appear to be in great pain? Depending on your situation (e.g., a backyard trail horse versus a show horse), any lameness may be the right time to call the vet, says Timm. Anytime the lameness is so severe that it is altering your horse s ability to move around comfortably to eat and drink, (calling your practitioner) is a must.

4 Schlachter notes that the veterinarian who tended to her horses growing up had a policy called a two-week rule for a-minor lameness without an obvious acute cause. If the lameness is gone in two weeks time, then it wasn t anything to worry about, she explains. Though Schlachter sometimes adheres to this approach in her practice, she says that with recent advances in technology and treatment, calling the veterinarian as soon as possible can often prevent the injury from worsening, shorten recovery time, and improve the outcome. Further, when a veterinarian determines the diagnosis, he or she can describe the severity of the situation, helping an owner decide what steps to take going forward. A bruise or even an abscess usually can be easily managed and will resolve. Soft-tissue injuries, caught early, might do well with rest. Chronic problems such as ringbone, sidebone, and arthritis might require long-term management. Laminitis can be life-threatening and must be treated immediately. A knee or ankle chip might rarely bother a weekend trail horse, whereas it could prove painful and costly to a high-level performance horse. Conducting the Lameness Exam A typical lameness exam begins with collecting a case history, says Timm. That is where owners input is vital because they can trace what they saw, when they saw it, and how it progressed. Timm says she conducts the physical exam next, looking for heat, swelling, pain response to basic palpation and manipulation of the limb, and a hooftester exam. Hoof testers help veterinarians detect pain and its location in the foot. Hoof testers are limited by the malleability of the hoof wall, sole, and frog, says Timm. Some horses are also chronically reactive to sole pressure from the hoof testers, but that may not be the source of an acute onset lameness in that horse.

5 The veterinarian also watches the horse move in a straight line and in circles at different gaits and on different surfaces, which helps him or her diagnose which leg has the problem. The rule of lameness in the front end is down on the sound, meaning the horse s head goes down when the sound leg is on the ground, says Schlachter. The hind end is a bit more complicated, but in general the hip with the greater movement is the lame leg, because the horse lifts his hip to avoid bearing weight in the painful limb. Just like our Warmblood dressage gelding, who threw his owner and veterinarian for a diagnostic loop, horses are good at compensating for lameness in one leg by shifting their weight to another. For that reason, Schlachter says, the trot, where two diagonal limbs hit the ground at the same time, is the most useful gait for diagnosing lameness. When a horse has a right front lameness, it will shift some weight backward to the left hind, so the horse will look off up front and behind, she says. Timm explains that this weight shifting frequently accompanies limblameness. Horses may look off in another limb due to compensatory unloading (of a hind limb, as Schlachter described), resulting in a head nod that may look like a forelimb lameness, she says. Next, once he or she has determined the affected leg, the veterinarian might perform nerve blocking. By effectively blocking the pain in an area by injecting a numbing agent and causing the horse to go temporarily sound, the veterinarian can often pinpoint the spot causing the problem. He or she typically starts this process at the foot and progresses up the leg. Though generally called nerve blocking, this diagnostic method can be used around the nerves or in joints.

6 A perineural block will block the joint and surrounding structures say, the fetlock joint and the suspensory (ligament) branches, says Schlachter. An intra-articular block would block the joint itself without the surrounding structures, until the numbing agent diffuses out of the joint. Timm points out that while blocking won t lead to a specific diagnosis in most cases, it helps a veterinarian localize the problem to know which structures to examine further with diagnostic imaging. Radiographs (X rays) allow veterinarians to detect bone problems such as arthritis or knee chips, while ultrasound gives them the ability to assess soft tissue and bone surfaces for damage (including emerging tendon problems). If they re unable to diagnose the underlying cause with either of those tools, a veterinarian might recommend MRI, CT, or nuclear scintigraphy (bone scan). Such imaging will likely require referral to a facility equipped with those diagnostic tools and could require anesthesia. With a bone scan, the horse must stay at the facility until the injected radioactive isotope used for that imaging modality clears his system. Costs also rise considerably with these tools. Both MRI and nuclear scintigraphy can run several thousand dollars, says Timm. So they are not generally the first line of diagnostics until other modalities have been used and often treatments tried with no improvement. Horses may look off in another limb due to compensatory unloading. DR. KIRSTE TIMM These advanced diagnostics do allow veterinarians to find lamenesses and their causes more often and earlier. And because horses compensate for lameness using sound limbs, solving the primary lameness might prevent a secondary one from developing.

7 Multi-limb lameness is one of the most common reasons for treatment failure, says Schlachter. This is where having a whole-horse approach becomes-imperative. Take-Home Message Horse owners are in the best position to detect lamenesses early. Veterinarians use owner information in tandem with a thorough soundness examination to pinpoint the lameness, find the cause, and treat it. They start at the foot and work up, as many lamenesses stem from problems in the foot, pastern, fetlock, cannon bone, or up to the knee or hock. However, some lamenesses are caused by problems higher in the body, a subject we ll cover in the upcoming second installment of this series.