Landmark research in Ireland has identified the genetic markers that indicate a racehorse is of significant susceptibility to roaring, a breathing condition that impacts 18 per cent of thoroughbreds.
The research was published in the current edition of the Equine Veterinary Journal and may prove crucial to combating the onset and prevalence of the performance-limiting disorder Recurrent Laryngeal Neuropathy (RLN).
It is hoped that the discovery of the genetic markers which identify horses with a three-times higher risk of developing the disease, may result in a genetic test for the condition.
While scoping of the upper respiratory tract when a horse is sold as a yearling or a two-year-old may identify an issue, it is a far from fail-proof method of determining if a horse will be diagnosed later with laryngeal hemiplegia, or roaring as it is more commonly known.
Horses can race as roarers, but it is generally seen as a performance-limiting.
Researchers at the University College Dublin and Equinome examined 200 horses in training from the stable of leading trainer Jim Bolger.
Genetic tests were then conducted on those horses to determine if there was a genetic connection.
"Accurately diagnosing disease using gold-standard methodologies is one of the most important factors in a genetic study," project lead Lisa Katz, UCD Professor in Equine Internal Medicine, told the University College Dublin website.
"Following years of intensive veterinary examination of the horses, it is extremely rewarding to see our research come to fruition."
It is hoped that a genetic test can be developed to identify those with an increased chance of developing the condition. The determination of the genetic risks of roaring could also have a significant impact on stallion and broodmare selection across the global thoroughbred industry.
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"As well as identifying horses with an increased risk of disease, this new information could also inform breeding guidance to reduce the incidence of the disease and provide targets for new therapies,” UCD Professor in Equine Genomics and Chief Science Officer at Equinome, Emmeline Hill said.
Professor Katz said identifying which horses may be at an increased risk of roaring would allow customise training and earlier intervention.
"Understanding the genetic risk of your horse for roaring can help with early intervention and management. This might include monitoring highly predisposed horses more closely and considering surgical interventions at an earlier stage to improve treatment success,” she said.
The full study is available online and includes a thorough explanation of the methodology, including the reason to use horses from one training operation.
“To maximise identification of the genetic contribution to the trait, the majority (92 per cent) of the study horses were bred, managed, and trained at the same premises by one trainer, controlling for environmental variation as far as possible,” it read.
Science Foundation Ireland funded the research.
