Top Lameness and Surgery Studies of 2014 By Erica Larson, News Editor /The Horse It was standing room only during the ever-popular Kester News Hour at the 2014 American Association of Equine Practitioners (AAEP) Convention, held Dec. 6-10 in Salt Lake City, Utah, as veterinarians from around the globe caught up on the latest research on a variety of horse health topics. During the hour, Lisa Fortier, DVM, PhD, Dipl. ACVS, professor of Large Animal Surgery at Cornell University’s College of Veterinary Medicine, in Ithaca, New York, shared her picks for the top surgery- and lameness-related studies. This was Fortiers final year co-anchoring the news hour; in 2015 Liz Santschi, DVM, Dipl. ACVS, professor of equine surgery at Kansas State Universitys College of Veterinary Medicine, in Manhattan, will take the reins. Stem Cell Therapy to Treat Stifle Lesions Fortier began by describing a landmark paper in which the authors evaluated the outcome of horses with meniscal, cartilage, or ligamentous stifle lesions treated with a combination of surgery and intra-articular (in the joint) mesenchymal stem cells (MSCs) and hyaluronic acid injections. She said that 44% of all study horses returned to work following treatment; of those, 75% of horses with meniscus disease returned to work (compared to 60% of control horses). She noted that there was no significant difference between the number of treated and control horses with cartilage or ligament damage that returned to work. She cautioned that 9% of study horses experienced joint flare (inflammation) following treatment, but said its difficult to tell whether the MSCs or HA caused the flare. Fortiers take-home for practitioners was that stem cells appeared to benefit horses with meniscal lesions. Ferris DJ, Frisbie DD, Kisiday JD, et al. Clinical outcome after intra-articular administration of bone marrow derived mesenchymal stem cells in 33 horses with stifle injury. Vet Surg. 2014;43(3):255-265. Oral Joint Supplements in Old Horses Next Fortier reviewed a study in which researchers tested the effectiveness of a joint health supplement (containing glucosamine, chondroitin, and methylsulfonylmethane, or MSM) coupled with exercise on improving stiff gait in aged horses. The team found that, after three months, all study horses fetlock extension improved at both the walk and the trot, regardless of whether they received the supplement. Thus, the researchers stressed the importance of exercise on keeping old horses joints working smoothly. Maybe some of these supplements work, maybe others dont, Fortier said. But the important thing is to keep old horses moving. Higler MH, Brommer H, LAmi JJ, et al. The effects of three-month oral supplementation with a nutraceutical and exercise on the locomotor pattern of aged horses. Equine Vet J. 2014;46(5):611-617. Nerve Block Variability Next, Fortier described two studies evaluating blocks for the deep branch of the lateral plantar nerve, a procedure often used to diagnose hind limb suspensory desmitis. The study authors evaluated approaches to block the nerve, volume of analgesic injected, and how much the analgesic diffused once it was inside the horses leg. The studies showed that theres a high degree of variability when it comes to these nerve blocks, Fortier said. The researchers found that high-volume injections diffused more than low-volume ones, and analgesia can travel up to 2 centimeters above and up to 5 centimeters below the injection site. Additionally, they found that 37% of horses showed evidence of having analgesia in the tarsal sheath, and 24% of horses showed evidence of having block diffuse into the tarso-metatarsal joint (one of the low-motion joints in the hock). All this boils down to Fortiers take-home message: Blocks arent specific. So, if the horse responds favorably to the nerve block, use diagnostic imaging including radiographs, ultrasound, and even more advanced modalities such as computed tomography (CT) and MRI (especially if there are no significant findings on radiographs or ultrasound) to determine whats going on. Additionally, she recommended practitioners use an aseptic (sterile) technique and a low-volume 2- to 3-milliliter block because they could be inadvertently entering a joint or tendon sheath. Contino EK, King MR, Valdes-Martinez A, et al. In vivo diffusion characteristics following perineural injection of the deep branch of the lateral plantar nerve with mepivacaine or iohexol in horses. Equine Vet J. 2014; epub ahead of print. Claunch KM, Eggleston RB, Baxter GM. Effects of approach and injection volume on diffusion of mepivacaine hydrochloride during local analgesia of the deep branch of the lateral planter nerve in horses. J Am Vet Med Assoc. 2014;245(10):1153-1159. Computed Tomography to Assess Hock Lameness Next, Fortier described a paper in which researchers retrospectively evaluated CT findings in horses with tarsal (hock) lameness. Some horses (in the study) had inconclusive ultrasounds or radiographs, others were to further assess fractures, and some has issues identified on another modality, she explained. This study was further investigation to extent of pathology. The team found a variety of pathology within the hock, Fortier said, some of which wasnt visible on other imaging modalities. Thus, she encouraged practitioners to seek further diagnostic information via a 3-D modality (like CT or MRI) if radiographs and/or ultrasound appear clean in a horse exhibiting hock lameness. Raes E, Bergman HJ, Van Ryssen B, et al. Computed tomographic features of lesions detected in horses with tarsal lameness. Equine Vet J. 2014;46(2):189-193. Abnormal Breathing Patterns and Respiratory Disease Changing gears, Fortier turned her attention to a study in which researchers evaluated whether abnormal breathing patterns at the canter and gallop are associated with respiratory tract disease. The team retrospectively studied 365 horses that had been referred for evaluation due to poor performance or an upper respiratory tract obstruction. Fortier explained that when most horses gallop, they take one break for every stride; however, researchers observed that a 2:1 breathing pattern—when a horse takes one breath over two strides—was the most common abnormal breathing pattern. The team also determined that the frequency of abnormal breathing patterns decreased as horses speed increased. Additionally, they determined that horses with a 2:1 pattern at higher speeds are more likely to have upper respiratory tract disease, while those with abnormalities at lower speeds could have either upper or lower respiratory tract disease. Fortiers take-home from this study was that while not every horse with an airway obstruction will have a 2:1 breathing pattern, all affected horses warrant further investigation of both the upper and lower respiratory tracts. Fitzharris LE, Franklin SH, Allen KJ. The prevalence of abnormal breathing patterns during exercise and associations with dynamic upper respiratory tract obstructions. Equine Vet J. 2014; epub ahead of print. Impact of Head and Neck Position Moving forward, Fortier described a group of studies evaluating the impact of horses head and neck positions while working. First, she touched on a study in which researchers determined that three of four head and neck positions (including hyperflexion, or rollkür) resulted in a decreased pharyngeal diameter; the only one that did not was natural, unrestricted head carriage. This indicated that all non-natural head and neck positions decrease pharyngeal diameter, Fortier said. She also noted that, as AAEP veterinarians, its important to advocate for function rather than form and to get involved with regulatory bodies involved in equitation events. The next study she described showed that while theres been some improvement in eliminating hyperflexion from upper level dressage, its not enough: These findings support the hypothesis that, in recent years, (Fédération Equestre Internationale) dressage judges have not penalized horses for a head position behind the vertical, the study authors wrote. Fortier then described a study in which researcher soughts to determine if artificial head and neck positions led to an increase in conflict behavior and/or stress. The team used the following five head and neck positions: unrestrained (HNP1); neck raised, bridge of nose around the vertical (HNP2); neck lowered and considerably flexed, bridge of nose pointing toward the chest (hyperflexion, HNP4); neck raised and extended, bridge of nose in front of the vertical (HNP5); and neck lowered and flexed, bridge of nose pointing toward the knee (HNP7). The researchers found that HNP2 caused increases in all stress parameters and conflict behavior and that those parameters stayed elevated for 30 minutes following exercise. Fortier said HNP4 was a close second, followed by HNP7; HNP1 was the most favorable position. We need to address the effects of head and neck position on stress and the welfare of the horse, she said. This is not just a rollkür problem. This is not just a dressage problem. Go LM, Barton AK, Ohnesorge B. Pharyngeal diameter in various head and neck positions during exercise in sport horses. BMC Vet Res. 2014;10:117. Lashley MJ, Nauwelaerts S, Vernooij JC, et al. Comparison of the head and neck position of elite dressage horses during top-level competitions in 1992 versus 2008. Vet J. 2014;202(3):462–465. Smiet E, Van Dierendonck MC, Sleutjens J, et al. Effect of different head and neck positions on behaviour, heart rate variability and cortisol levels in lunged Royal Dutch Sport horses. Vet J 2014;202(1):26-32. Dynamic Laryngeal Collapse Fortier stayed on the respiratory tract for the next study, focusing on bilateral dynamic laryngeal collapse (DLC). She explained that veterinarians still dont know what causes the condition or if its neuromuscular in origin, similar to laryngeal hemiplegia (roaring). But the researchers determined, after taking and analyzing several types of muscle biopsies from affected horses and controls, that horses with DLC had no differences in their biopsies compared to control horses. Fortier said this showed that DLC is not neuromuscular in origin, but were still not sure what causes it and encourage all to stay vigilant for observational causes. Fjordbakk CT, Revold T, Goodwin D, et al. Histopathological assessment of intrinsic laryngeal musculature in horse with dynamic laryngeal collapse. Equine Vet J. 2014; epub ahead of print. Treating Kissing Spines Surgically Next, Fortier described two studies in which researchers evaluated new techniques for surgically treating overriding dorsal spinous processes, more commonly known as kissing spines, that did not respond to conservative management. One of the papers described a technique in which the surgeon removed an overriding part of the spinous process with the horse in lateral recumbency (laying on his side). Nearly 80% of horses from this study were sound at one year post-surgery, she said, and the procedure had an excellent cosmetic outcome. The researchers also determined that 44% of affected horses were hot on a bone scan along their spine, indicating nuclear scintigraphy could serve as an alternative diagnostic modality to radiographs. The researchers behind the second study described performing the same procedure, but in a standing, sedated horse. In this case 80% of the horses included in the study were sound one year following surgery, Fortier said. She stressed the importance of getting a complete diagnosis if you suspect kissing spines. She also noted that 37% of unaffected horses have radiographic evidence of kissing spines without displaying outward clinical signs. Jacklin BD, Minshall GJ, Wright IM. A new technique for subtotal (cranial wedge) ostectomy in the treatment of impinging/overriding spinous processes: description of technique and outcome of 25 cases. Equine Vet J. 2014;46(3):339-344. Brink P. Subtotal ostectomy of impinging dorsal spinous processes in 23 standing horses. Vet Surg. 2014;43(1):95-98. Type of Lesions Impact on Neurectomy Success Fortier changed gears and shared a study in which researchers evaluated how the type of deep digital flexor tendon lesion (DDFT) located in a foot lesion, as diagnosed via MRI, affects the outcome of a neurectomy (surgically cutting the nerves leading to the foot). The team found that 92% of horses were sound following surgery, and 80% returned to athletic function for at least 20 months. She cautioned that horses with core and linear DDFT lesions did not have as favorable an outcome as those with dorsal border lesions of the DDFT or other foot lesions. Additionally, six horses underwent follow-up MRI, Fortier said. From these results, the team learned that if horses jumped following neurectomy, their lesions worsened. Gutierrez-Nibeyro SD, Werpy NM, White NA, et al. Outcome of palmar/plantar digital neurectomy in horses with foot pain evaluated with magnetic resonance imaging: 50 cases (2005-2011). Equine Vet J. 2014; epub ahead of print. Cheek Teeth and Motorized Floating Systems Fortier concluded her Kester career with a look at dentistry. She described a study in which researchers evaluated how much heat is transferred into horses cheek teeth pulp cavities when veterinarians use a motorized implement during floating. Her key take-homes from this study: Keep the rotational speed as low as possible, as doubling the speed halves the time it takes for the pulp to reach a critical temperature (or that at which damage occurs); Limit grinding to 30 seconds in one location; Negative effects are more pronounced in maxillary teeth (upper cheek teeth) than the mandibular teeth (lower cheek teeth); and Because additional heating can occur after grinding takes place, wait twice as long before carrying on for the tooth to cool (so if you spent 30 seconds grinding, allow the tooth a minute to cool). She concluded by noting that motorized implements can both smooth teeth and create a smooth surface layer without tearing or chipping the tooths dentin, and that diamond disc burrs are ideal for protecting the dentin and creating a smooth surface. Haeussler S, Luepke M, Seifert H, et al. Intra-pulp temperature increase of equine cheek teeth during treatment with motorized grinding systems: influence of grinding head position and rotational speed. BMC Vet Res. 2014;10:47.
Posted on: Tue, 27 Jan 2015 14:52:01 +0000