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 2017 AAEP CONVENTION SPONSORED BY A38 TheHorse.com/AAEP2017 AAEP Wrap-Up THE HORSE March 2018 ALEXANDRA BECKSTETT; CLAIR THUNES, PHD SAA Detects Early Inflammation in Frequent Flyers E lite sport horses that fly around the world are at a particularly high risk of exposure to infectious disease— due to comingling with other horses and increased stress on their immune systems—and contracting one could sideline them indefinitely. The sooner vet- erinarians can identify and begin treating a sick horse, the better for all involved. So Marc Oertly, DVM, of the Swiss In- stitute of Equine Medicine, in Berne, set out to determine whether serum amyloid A (SAA) concentrations could suggest inflammation sooner than a rectal ther- mometer in traveling horses. Serum amyloid A is a protein present in undetectable to low levels in healthy horses. The liver releases SAA into the bloodstream in response to inflammation, causing levels to rise 1,000-fold or more. Vets can measure these levels to detect infection and monitor treatment response. In a study funded by StableLab, a company that developed a stall-side blood test to measure SAA in horses, Oertly evaluated the optimum time point for measuring SAA after horses travel. He followed 121 high-level Warmblood show jumpers, ages 8 to 17, along three stops of the Longines Global Champions Tour. All horses first flew to Miami, Florida, and vets ran a stall-side SAA reading and health check prior to the flight, upon ar- rival to quarantine, 24 hours after arrival, and 48 hours after arrival. Veterinary staff took rectal temperatures twice daily. Then horses flew to Mexico City and Shanghai, where Oertly repeated this process. Of these horses, 31 developed clinical signs of a problem (e.g., coughing). All 31 had elevated SAA levels, but only one had a high temperature. The sick horses' SAA levels were above 35 µg/mL 24 to 48 hours before they started showing clinical signs. "There was a significant difference in SAA levels between healthy and sick horses," said Oertly, adding that "SAA has a much higher sensitivity than rectal temperature." At 24 hours after horses' arrival, SAA had 86.7% sensitivity (ability to identify a sick horse correctly) and 91.9% specificity (ability to identify a healthy horse cor- rectly), compared to 3.2% sensitivity and 100% specificity with rectal temperature. "SAA should be added to the physical exam as standard protocol to evaluate health in high-risk horses," said Oertly. "If I detect a horse as early as possible, I might have time to treat the horse to still perform at the highest level." He said SAA is a more reliable indicator of inflammation than rectal temperature in traveling horses, and the ideal time to perform an SAA reading is 24 hours post-arrival, using a 35 µg/mL threshold. Of course, additional diagnostics are war- ranted if a horse's SAA levels rise. Uncovering Coronavirus Risk Factors Equine coronavirus is newer on the scene than most equine diseases we hear about, with vets reporting the first outbreaks among adult horses just a few years ago. Practitioners know it causes fever, anorexia, diarrhea, and colic in af- fected horses. To prevent it, however, they need to better understand what increases a horse's chances of infection. Nicola Pusterla, DVM, PhD, Dipl. ACVIM, professor of medicine and epi- demiology at the University of California, Davis, School of Veterinary Medicine, looked at data on thousands of horses from all over the U.S. to find risk factors. He explained that there's been a steady increase—from 4% to about 9%—in laboratory-confirmed coronavirus cases in adult horses since 2010 (when scien- tists introduced the qPCR diagnostic test for coronavirus to the U.S.). "About one in 10 horses in the United States will test positive for coronavirus, but fewer than 20% of those will show signs," he said. The disease is widespread and occurs more frequently in colder months, he said, "likely due to husbandry changes and an increase in young stock on the ground (the virus is commonly found in foals)." Explosive outbreaks of this highly COURTESY FEI/GABRIEL NASCIMENTO Getting Ahead of Infectious Diseases AAEP @AAEPHorseDocs "Flu can spread further based off coughing. If your horse shares airspace with a flu-stricken horse, they are exposed." — Dr. Josie Traub-Dargatz on outbreak control and biosecurity.