The Horse

MAR 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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YOUR GUIDE TO THE 2018 AAEP CONVENTION A36 March 2019 The Horse | AAEP Wrap-Up ALEXANDRA BECKSTETT ERICA LARSON How Firocoxib Could Benefit Colic Surgery Patients E ndotoxemia—the presence of endotoxins in the bloodstream—is a significant and potentially deadly complication of colic and other gastroin- testinal (GI) diseases in horses. But could something as simple as a change in anti- inflammatory drug selection help stave off endotoxemia and promote gut healing? Amanda Ziegler, DVM, PhD, a postdoctor- al research fellow at the North Carolina State University College of Veterinary Medicine, in Raleigh, and colleagues have proven it's possible, at least with small intestine strangulating obstructions. Non-steroidal anti-inflammatory drugs (NSAIDs) target cyclooxygenase (COX), an enzyme responsible for the body's inflammatory responses. There are two COX "subtypes": COX-2 is primarily associated with inflammation develop- ment and, so, can contribute to signs of endotoxemia, while COX-1 is associated with normal inflammation-prevention or - attenuation processes such as protecting the gastric mucosa (lining) and promot- ing gut barrier function. This barrier is important because it's what can keep endotoxin—released after a proliferation and die-off of Gram-negative gut bacteria sparked by colic—from leaking into the bloodstream at levels that can overwhelm the immune system and be deadly. While traditional NSAIDs, such as flu- nixin meglumine (Banamine), block both COX-1 and -2, (and, so, are referred to as nonselective), some newer ones—like firocoxib—are selective, designed to tar- get COX-2-associated inflammation while sparing COX-1 enzymes that could help prevent endotoxemia development. Studies have shown that in equine small intestine strangulating obstruction models, barrier recovery (which needs to happen after the tissue injury) occurred faster with COX-2-selective NSAIDs than with nonselective NSAIDs, Ziegler said. To further investigate, she and her co- authors administered flunixin meglumine or firocoxib to 56 horses admitted to three university hospitals for surgical treatment of small intestine strangulating obstruc- tions. They collected blood samples before and after surgery, evaluating them for endotoxemia biomarkers. Ziegler said they found that: ■ Both NSAIDs controlled horses' pain and heart rates (increased rates are indicative of pain) effectively; and ■ Horses treated with firocoxib had lower plasma sCD14 (an endotoxin biomark- er) levels compared to their flunixin- meglumine-treated counterparts. Ziegler and colleagues concluded that firocoxib and flunixin meglumine pro- vided similar levels of pain control, but the firocoxib resulted in reduced evidence of endotoxemia at 48 hours post-surgery. She said additional studies with larger numbers of horses could allow research- ers to detect differences in short-term survival and complication risk. A New Tool for Helping Predict Colic Surgery Need? If a horse needs colic surgery, the soon- er he gets to the operating room, the bet- ter. But, in the early stages of diagnostics, it can be challenging for vets to determine whether a colicking horse could recover with medical management or if he has an issue—such as a strangulating lesion— that must be corrected surgically. Fortunately, researchers are helping make the decision more straightforward to expedite the process. Isabelle Kilcoyne, MVB, Dipl. ACVS, suggested measuring a biomarker—the enzyme creatine kinase (CK)—in peritoneal (abdominal) fluid to help distinguish horses with ischemic (lacking blood flow) intestine due to a strangulating lesion from those without. Vets frequently collect and analyze peri- toneal fluid during work-ups of colicky horses, said Kilcoyne, an assistant profes- sor at the University of California, Davis, School of Veterinary Medicine. In a study in rabbits, researchers determined that peritoneal CK levels increased significant- ly within an hour after ischemic injury. And, veterinarians know that horses with elevated blood plasma CK levels are less likely to survive surgery than those with levels under 470 IU/L, based on a study out of Colorado State University. Kilcoyne and colleagues sought to find out if CK could be a useful marker of intestinal ischemia and, therefore, an indicator a horse needs surgery. The researchers gathered information from colic cases arriving to their clinic. At admission they collected blood and peritoneal fluid samples from: ■ 21 horses ultimately diagnosed with strangulating intestinal lesions; ■ 40 ultimately diagnosed with colic but not strangulating lesions; and COURTESY DR. AMANDA ZIEGLER Gastrointestinal Health

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