The Horse

JAN 2019

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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32 January 2019 The Horse | TheHorse.com However, veterinarians have blamed their use for several complications. So Anderson explored whether they should remain the gold standard. How They're Used Intra-articular corti- costeroid use in horses with joint issues is prevalent. In one survey, said Anderson: ■ 85% of responding veterinarians used it to manage chronic joint inflammation; ■ 75% used it in horses with radiograph- ic evidence of OA; and ■ 70% used it to treat acute joint pain. The three most commonly used corti- costeroids are triamcinolone acetonide (TA), methylprednisolone acetate (MPA), and betamethasone sodium phosphate- betamethasone acetate (BM). Researchers have confirmed their efficacy, showing that MPA improved lameness 56-70 days post-administration, and TA improved lameness 42 days post- administration, with 50% of horses still sound three months later. Concerns Certain corticosteroids can actually have deleterious effects on joint cartilage. Their use "sets into motion a destructive cycle," said Anderson. He cau- tioned against using MPA, in particular, because it causes cartilage degradation. On the other hand, TA is classified as chondroprotective (safeguards the joint), he said, and doesn't have the same nega- tive effect on cartilage as MPA. Another concern is the purported risk of corticosteroid-induced laminitis (a dis- ease in which the laminae attaching the coffin bone to the hoof wall fail). Several studies, however, have proven corticoste- roid-induced laminitis to be very rare and not directly attributable to the corticoste- roid being used. Horses at most risk are those with metabolic conditions. Septic arthritis (painful joint inflam- mation caused by infection) is another serious, albeit uncommon, complication of IA corticosteroid administration. An- derson said treated joints have a reduced ability to fight infection compared to healthy joints. In one study researchers reported that IA corticosteroids increase a horse's likelihood of sustaining a catastrophic injury post-treatment, but Anderson said the perceived link might be an indirect ef- fect of increased loading on a pathologic (damaged or diseased) joint. Lastly, there's concern over the com- petitive advantage corticosteroids might give affected athletic horses over healthy ones. For this reason, racing authorities and governing equestrian bodies have es- tablished guidelines and threshold limits for corticosteroid administration. The Bottom Line After reviewing the literature, Anderson concluded that IA corticosteroids should still be our friends. While we can't lump all corticosteroids into one category, they "should still be considered a mainstay of treatment of IA inflammation of whatever cause," he said. "Multiple joints can be injected multiple times within safe limits, and sepsis should not be an expected complication if ap- propriate injection practices are adopted. Not all corticosteroids are the same, and TA confers advantages over MPA in most studies. Their effect should be long-lasting and result in good clinical improvement in lameness and effusion (swelling)." Alternatives for Managing Arthritis When managing equine osteoarthritis equine practitioners focus on reduc- ing pain, improving joint function, and minimizing deterioration of joint tissues. A variety of therapies exist, but IA cor- ticosteroids remain the most common first line of defense, said Niklas Drumm, DrMedVet, Dipl. ACVS-LA, ECVS, a shareholder and practitioner at Tierklinik Lusche, in Germany. But two relatively new therapies—polyacrylamide hydro- gel (PAAG) and stanolozol—might offer alternative treatment options. DISCOVERY AND DISCUSSION Suspensory Branch Tears: Surgery and Outcome Suspensory ligament branch (SLB) injuries are common in equine athletes such as show jumpers, dressage horses, and racehorses. While the prognoses of affected sport horses is fair, in Thoroughbred racehorses they're poor. Ian Wright, MA, VetMB, DEO, Dipl. ECVS, Hon- FRCVS, hospital director of Newmarket Equine Hospital, in Suffolk, U.K., described surgical treatment to bring racehorses back to function. The suspensory ligament, which runs down the back of the cannon bone, divides into two branches that attach to the sesamoid bones at the back of the fetlock. Injury to the branches causes significant wast- age in Thoroughbreds, said Wright. Because SLB tears heal by scar tissue, horses cannot regenerate the structure post-injury. To find out if removing the affected tissue would help, Wright conducted a retrospective study of 29 Thoroughbred racehorses admitted to Newmarket Equine Hospital 2007-2015 with SLB lesions that were treated surgically. Surgical exploration revealed that all horses had defects at the palmar/ plantar (ground-facing) SLB margin and evidence of adhesions and scar or granulation tis- sue. Surgeons removed disrupted SLB fibers and debrided scar tissue until left with healthy margins. Postoperatively, horses received non-steroidal anti-inflammatories and remained bandaged for about 23 days. The team removed closure staples at around Day 13 after surgery. Horses received two to three weeks of rest, followed by six to eight weeks of walking, before progressing to trotting, etc. Of the 28 horses available for follow-up, he noted that: ■ 19 (65%) returned to racing; ■ Of those, it took six to 30 months (mean 15 months) until they made their first start back; ■ Recovered horses made one to 27 (mean nine) starts; ■ 14 horses placed, with 10 winning; and ■ Only one horse had a documented reinjury. "Surgery appears to have a good prognosis and has proved superior to noninvasive management," in his experience, said Wright. He added, however, that this treatment is very lesion-specific and not applicable to all suspensory branch injuries.—Alexandra Beckstett Surgically removing disrupted fibers and de- briding scar tissue can help repair SLB injuries. COURTESY DR. IAN WRIGHT

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