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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34 January 2019 The Horse | TheHorse.com Polyacrylamide Hydrogel This nonde- gradable synthetic watery gel integrates safely with soft tissues, said Drumm. Physicians have used it for more than 15 years to treat stress incontinence in women and to reinforce facial tissues. Veterinarians inject PAAG directly into affected equine joints. "Two of the proposed modes of action for PAAG are to decrease joint capsule stiffness and vis- cosupplementation (injecting lubricating fluid into the joint)," Drumm said. In studies in goats and horses, a layer of PAAG persisted in joints up to two years after injection. In a 2015 study of 43 os- teoarthritic horses getting IA PAAG, 82.5% were sound 24 months post-treatment, with more becoming sound over time. In another study of 54 racehorses with OA, 83.3% experienced improved soundness. In a recent study at Tierklinik Lusche, Drumm and colleagues evaluated 12 horses with coffin joint OA treated with IA PAAG after not responding to previous approaches. Eight returned to sound- ness, two improved, and two remained unchanged. He concluded that PAAG is a safe and promising new therapy that has up to a 70% success rate returning stub- born OA cases to soundness. Stanolozol This synthetic anabolic steroid has fallen into disfavor and been labeled a banned substance due to its abuse as a performance-enhancing drug in both human and equine athletes, said Drumm. However, it's been shown to be safe and have chondroprotective effects. In a 2015 study of 24 horses with acute or chronic fetlock OA, stanolozol improved lameness in 83.3% of horses receiving multiple IA doses. At 60 days post-treatment, 71.4% of acutely arthritic horses were sound, 95.7% of chronically arthritic horses had improved, and 57.9% of chronic cases were sound. Drumm cautioned that IA stanolozol for joint disease treatment cannot be dif- ferentiated from intramuscular use as a performance-enhancing drug. "While IA corticosteroids are still the first line of defense, (PAAG and stanolo- zol) can be used as alternatives or addi- tives," he said. Managing Strangles on the Farm A new horse arrives at your boarding barn. He gets turned out with other hors- es, and all seems well. But after a week, he gets an abscess under his jaw, and a few of his pasturemates are coughing. Do they have strangles? Is the whole barn at risk? This is a panic-inducing scenario many veterinarians might encounter. David Rendle, BVCs, MVM, CertEM(IntMed), Dipl. ECEIM, MRCVS, of Rainbow Equine Hospital, in North Yorkshire, U.K., described how to handle it. Strangles develops when Streptococcus equi bacteria infect the head and neck lymph nodes, sometimes causing painful abscesses. It's highly contagious and can spread rapidly. Clinical signs When evaluating a sus- pected case, said Rendle, the veterinarian must first get a case history and a time- line of the clinical signs, which typically include lethargy and fever (usually the first you'll see, within three to 14 days of exposure), cough, and the telltale abscess. Fever occurs before horses are conta- gious, providing an opportunity to isolate and halt the spread of infection, he said. About two to three days after fever de- velops, the horse typically starts shedding bacteria via pus-filled nasal discharge. This can last for two to three weeks or longer if infection sets up in the sinuses or guttural pouches (cavities in the back of the head), he said. One to four weeks later abscesses develop and burst. Rendle said infected horses might also show less-obvious signs of mild transient fever, mild clear discharge, and lack of ap- petite, yet never develop abscesses. "Often these horses are the ones that spread the most disease," he said. "Transmission from outwardly healthy horses is often more of a problem than transmission from horses with clinical signs." Diagnosis A vet's ability to confirm strangles depends on disease stage, which isn't always known. Rendle suggested flushing the guttural pouches for culture and PCR testing over taking less-reliable nasopharyngeal swabs for chronic cases. For acute cases, he said, timing is critical. "S. equi doesn't reside in the nasal pas- sages, so you're reliant on timing and luck (with swabs)," he said. "It's only really ef- fective (as a diagnostic) in early infection with copious discharge." At least three weeks after all clinical signs on a farm have ceased, he suggested blood testing all horses to determine whether they're carriers. "Ten percent of horses in an outbreak are expected to develop persistent guttural pouch infec- tion," he said. These horses show no clini- cal signs yet continue to spread S. equi. Preventing spread If diagnostics do confirm strangles, Rendle said to isolate all horses with fever or other clinical signs immediately. Keep them in isolation DISCOVERY AND DISCUSSION A horse can be infected with S. equi for several weeks for an abscess develops and bursts. PAULA DA SILVA Ten percent of horses in (a strangles) out- break are expected to develop persistent gut- tural pouch infection." DR. DAVID RENDLE

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