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YOUR GUIDE TO THE 2017 AAEP CONVENTION SPONSORED BY A17 TheHorse.com/AAEP2017 March 2018 THE HORSE AAEP Wrap-Up The Latest on Lameness ALEXANDRA BECKSTETT; ERICA LARSON The Most Common Western Performance Horse Lamenesses esearchers have identified muscu- loskeletal issues prevalent among horses in many disciplines— knowledge that helps vets take steps to reduce injuries. However, until recently, these figures hadn't been well-quantified in Western performance horses. Sherry A. Johnson, DVM, and col- leagues investigated diagnostic blocking patterns (using analgesia to locate pain) in Western performance athletes. Johnson is a sports medicine and rehabilitation resi- dent at Colorado State University's (CSU) College of Veterinary & Biomedical Sci- ences, in Fort Collins, and Equine Sports Medicine LLC, in Pilot Point, Texas. The team reviewed 10 years of medical records of horses competing in West- ern performance classes and reining at nationally sanctioned competitions. They focused on identifying the affected limbs, lameness grades, and diagnostic analge- sia patterns. They only included horses with performance-related lameness and complete diagnostic work-ups. In all, they reviewed records from 2,677 lameness exams on 2,521 horses. The team knew specific disciplines for 73.5%—1,188 were all-around Western performance horses, and 616 were rein- ers. Most were Quarter Horse geldings. Key findings included: ■ The primary lame limb was the right forelimb in 809 horses, left forelimb in 695 horses, right hind in 616 horses, and left hind in 557 horses; ■ The average lameness grade was about 2 on a 5-point scale; ■ 56.3% of horses had a secondary lame- ness, 17.4% had a tertiary lameness; ■ All-around horses were most likely to have a single hind-limb lameness; and ■ Reining horses were most likely to have a single forelimb lameness. Regarding blocking patterns: ■ Veterinarians localized forelimb lame- nesses most commonly using a palmar digital nerve block (which numbs the heel and part of the hoof walls), an abaxial sesamoid nerve block (which desensitizes the entire hoof from ap- proximately below the fetlock joint down), or a combination of the two; ■ They localized hind-limb lamenesses most commonly to the proximal metatarsal/distal tarsal (top of cannon bone/lower hock) region (16% of cases). The team found 47 nonlocalizable hind-limb lamenesses, in contrast with 11 nonlocalizable forelimb lamenesses. "The pelvis as a source of pain that manifests itself as diagnostically nonlo- calizable hind-limb lameness should be considered in these cases," Johnson said. Ultimately, she said, the team found it's still challenging to pinpoint lameness source using diagnostic analgesia. But continued research on how Western per- formance horses respond to nerve blocks could help vets better define the most common injuries in that discipline. Sagittal Groove Injury Outcomes in Warmblood Horses The fetlock is a complex high-motion joint that joins the bottom of the cannon bone to the top of the long pastern; two sesamoid bones sit to the junction's rear. The long pastern's sagittal groove (which underlies the ridge in the bottom of the cannon bone) is a common site of race- horse injury. While many of these injuries in racing horses have a good prognosis for return to athletic function, how they im- pact other horses has remained unclear. Sarah Gold, DVM, carried out the first study evaluating MRI characteristics and outcomes of sagittal groove injuries in nonracing horses. Gold is a sports medi- cine vet at B.W. Furlong and Associates, in Oldwick, New Jersey, and Advanced Equine Imaging of Wellington, in Florida. Gold and colleagues reviewed medi- cal records from 2007 through 2016 and identified 19 Warmbloods with sagittal groove injuries examined using MRI. Four horses had a history of chronic lameness that became acutely severe; 15 had a one- to nine-week history of lame- ness. Gold said clinical signs were variable and not specific to the fetlock. How horses blocked to different diagnostic anesthesia injections also varied greatly and was not always specific to the fetlock. Vets didn't perform blocks on two horses, opting for nuclear scintigraphy (bone scan) to check for suspected fractures, with a plan for MRI based on results. All horses were BIANCA MCCARTY