The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
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36 TheHorse.com The horse April 2015 She says nuclear scintigraphy is a particularly important screening tool in young racehorses predisposed to stress fractures. It can be much trickier with middle-aged sport horses that have wear and tear from years of competition. Allen also notes that young horses have areas of natural bony change—a caveat that must be considered as routine when interpret - ing their images. Lameness Locator With lameness locator technology, sensors on the horse's poll, pelvis, and pastern allow the practitioner to note gait irregularities. "A lameness locator uses a combination of accelerometers and in - ertial gyroscopes to determine head bob, pelvic tilt, and lame limb in the stance- phase of the stride," explains Allen, noting that while this technology might not yet be in widespread use, it is a useful tool. Barrett finds lameness locators to be valuable for multilimb lameness evalua - tions and teaching situations. Learning Curve Becoming a diagnostic imaging expert doesn't happen overnight. Knowing which modality to choose and being skilled in that modality comes with exten - sive experience. "It's a complex question of what to do when," Allen says. "It takes a lifetime to figure out." One thing Barrett would like horse owners to keep in mind is that equine practitioners can't be experts in every - thing. "There are people who are good at a lot of things and people who are experts in certain things," she says. To that end, general equine practitioners consult with diagnostic imaging experts, just as primary care physicians refer patients to a variety of specialists. Whether for a backyard horse in for a lameness work-up or a high-end jumper undergoing a prepurchase exam, Barrett says specialists with intrinsic knowledge of equids and their craft can take imaging to the next level. h ABoUT The AUThor Natalie DeFee Mendik is an award-winning journalist specializing in equine media. Dandy Products, Inc. Padding & Flooring Specialists "Padding At Its Best" Breeding Sheds, Stocks, Stalls, Trailers, Exercise & Training Areas, Induction & Recovery Rooms Table & Surgical Pads, Neo-Natal Foal Beds Non-Slip Safety Floors for All Areas Pavesafe Bricks & Tiles, Trac-Roll & Vet-Trac Floors, Wash Stall, Grooming, Aisleway and Trailer Mats At a Glance: Where to Begin? So, you're trying to figure out why your horse is lame. But with such an array of imaging options out there, how do you know where to start? Jake Hersman, DVM, of Animal Imaging in Irving, Texas, shares his thoughts. "First and foremost, the horse owner and his or her veterinarian must strive to achieve a definitive diagnosis, which can help in formu- lating an effective treatment plan," he says. He outlines the following steps to consider during this process: ■ Exam Start with a complete history and thorough lameness evaluation by a qualified veterinarian, he says. It often consists of assessing the horse with or without tack, on soft and hard ground, and with flexion tests and hoof testers. If necessary, nerve blocks or regional anesthesia can help pinpoint the soreness. The veterinarian can use the results to determine the best imaging approach to use. ■ X-Rays Depending on the exam results, radiography might be the first diagnostic choice. Today's digital systems can help practitio- ners definitively diagnose bony pathology (disease or damage). ■ Ultrasound Soft tissue structures can be difficult to assess radio- graphically, so ultrasound often follows, particularly with tendon and ligament injuries. The veterinarian determines which area to image based on the initial lameness exam and regional block results. ■ MRI If the veterinarian localizes the lameness to a given area (especially in the lower limbs or head) and radiographs and/or ultrasound do not provide a definitive diagnosis, he or she might turn to MRI. "I believe MRI should be used earlier in the diagnostic process due to the remarkable ability of MRI to evaluate both bone and soft tissue disease in the horse," Hersman says. The veterinar- ian can only scan a small part of the horse at a time with MRI, so it's critical to narrow the soreness to an area first. ■ Scintigraphy One of the more common imaging options veterinar- ians turn to when they are unable to localize a cause of soreness is scintigraphy. This modality can capture subtle bone remodeling, and Hersman says it's useful for diagnosing abnormalities of the head, cervical spine (neck), and back and pelvis; bone bruising or lower limb contusions; obscure fractures; or other stress-related injuries. Scintigraphy might provide diagnostic clues in horses that are not performing as well as in the past or have other subtle lamenesses. It also often guides the examiner to additional imaging approaches. ■ CT This technology is useful primarily for skull problems in adult horses. A CT exam helps the veterinarian evaluate bone or dental issues, but the modality is less useful for evaluating soft tissue injuries. Your veterinarian might also use it prior to or after tooth extraction or for problems such as pneumonia and/or septic joints in horses smaller than 500 pounds. There are many important factors veterinarians and owners need to review prior to proceeding with extensive imaging. These include the modalities' costs and regional availability, as well as the horse's use.—Natalie Defee Mendik