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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11 January 2016 THE HORSE TheHorse.com For additional news items, see TheHorse.com/News Protecting Wild Horses in Patagonia, Chile In Cape Horn, Patagonia, Chile, resides a population of wild horses that has lived there for more than a century. The horses have adapted to survive and reproduce in the mountains and among swamps, rivers, and glaciers in one of the world's most adverse climatologi- cal zones, making them of great scientific interest. In 2014 a nonprofit organization was founded under Chilean law, allowing supporters to work to stop wild horse hunting and protect the equids in the future. And in 2015 the Association of Chilean Equine Veterinarians (ACHVE) signed an agreement with the organization in which it committed to guide the scientific study process needed to determine whether these horses can be defined as a unique species or as a group of horses adapted to this very adverse geographical area. Learn more about the horses and the people working to protect them at TheHorse.com/36937. —Maria Paz Zuñiga Barrera, DVM, WEVA Board Member ? Early-born domestic foals might have a tough start in life, with chilly winds and even snow welcoming them into the world. But there appears to be a payoff: Czech Republic researchers have determined that the season's older weanlings become—and tend to stay—more dominant in the social hierarchy. Martina Komárková, PhD, of the Institute of Animal Science's Department of Ethology, in Prague-Uhríneves, and colleagues recently studied 66 Kladruber (a Czech sport horse breed) mare and foal pairs in eight herds over two foaling and weaning seasons. They also looked at four of the resulting foal herds when the horses were three years old. The older weanlings were bigger and stronger, making it easier for them to win conficts, Komárková said. They've also had more time to develop social skills and learn from their experiences. And it's not just a phenomenon of the post-weaning season, she said: The researchers observed that even when the horses were 3, the hierarchy remained similar to that of weanling age. Learn more at TheHorse.com/36856. ? OLDER WEANLINGS APPEAR MORE DOMINANT THAN YOUNGER ONES ? DID YOU KNOW COURTESY DR. MARTINA KOMÁRKOVÁ Detecting myocardial (heart muscle) damage using blood tests that measure cardiac troponin I (cTnI) and T (cTnT) is routine in human medicine, but there's little data on using such tests in horses. "Troponin is a complex of three proteins—I, C, and T—that plays an integral role in cardiac muscle contraction," said Gunther van Loon, DVM, PhD, of Ghent University, in Bel- gium. "When the heart is damaged, those proteins are released from the muscle and circulate in the blood, where they can be measured." Several cTnI assays are available for use in horses, but each yields different results. There is only one cTnT assay. Van Loon and colleagues compared the tests in horses with and without cardiac damage. "Both cTnI and cTnT levels were higher in horses with primary myocar- dial disease than the healthy horses and the horses with secondary myo- cardial disease," he said. They also found a correlation between cTnI and cTnT, but noted there were quantita- tive differences between the tests. For example, the optimal cutoff (the value that distinguishes between normal and abnormal) for cTnI was 95 pg/mL, which was 10 times higher than the cutoff value for cTnT. Thus, he recommended veterinar- ians use the same assay they use initially on follow-up examinations. Read more at TheHorse. com/36754.—Stacey Oke, DVM, MSc Horses with XY sex chromo- somes are always male, right? Not necessarily. Sterile mares could actually have male chromosomes, which can make breeding stock selection hit or miss. But researchers are developing new diagnostic procedures could make this syndrome easier to detect. The "XY mare" chromo- somal abnormality often goes undiagnosed because these mares usually don't appear different than XX mares, said Sebastián E. Demyda-Peyrás, MSc, PhD, of the University of Córdoba, in Spain. But it could be a prevalent condi- tion, as scientists know horses have more chromosomal abnormalities than other domestic species. Equine chromosomal testing by karyotyping (which involves examining chromo- somes in a cell sample, plac- ing colored "bands" on certain parts of the chromosomes to make them more readable) is complicated and costly, Demyda-Peyrás said. So checking for XY chromosomes isn't a first-line diagnostic pro- cedure for sterile mares. "We wanted to find some- thing practical, efficient, and affordable," he said. So, he and colleagues evaluated four XY mares, all of which showed normal male chromosomes on a standard karyotype, Demyda-Peyrás said. Closer examination via molecular methods—looking at the DNA itself—revealed a "deletion" in the SRY gene (which is responsible for deter- mining sex). "Our findings helped us hone in on molecular markers that will … help us get the same genetic information, but in a quicker, easier, and cheaper way," he said. "We're in the process now of fine- tuning our detection of those markers." Learn more at TheHorse. com/36751. —Christa Lesté-Lasserre, MA STEPHANIE L. CHURCH XY mares appear physically normal, but are infertile. ISTOCK.COM New Procedure to Identify XY Mares in the Works Comparing Cardiac Marker Tests to Detect Heart Damage