Page 18 - The Game August 2006

18 The Game, August 2006 Your Thoroughbred Racing Community Newspaper
SHARPENING THE FOCUS ON EQUINE GENETICS
Mobility
An old friend, now with a Twist
A refreshing new class of equine supplement
Now Available as a Liquid Available in 1L & 4L sizes
Ok, so you likely won’t want to serve it on the rocks, but feel free to add to daily feed or use as a jug once a day.
Made from research proven plant extracts that give your horse superior
joint support in a daily dose.
MobilityTM is the only patented herbal remedy for arthritis. Top horse people have been using MobilityTM for nearly 10 years. 1 888 423 7777
www.horseherbs.com
that the
genetics of the condition are
Call for full catalogue page, photos, videos or more information
Equine Health
Since 1995, an international team of researchers have been quietly working away at a project of enormous importance: mapping the equine genome. Translating the cryptic base pairs on strands of horse DNA is far more than just an intellectual puzzle, it’s proving to be the key not only to diseases we suspected were genetically linked, but also to many health problems we previously had chalked up to other factors.
The progress of the Equine Genome Project has been tracked at biannual meetings since its inception. At the Fifth International Equine Gene Mapping workshop, in Kruger National Park in South Africa, in August 2003, researchers from across the globe were able to celebrate the completion of the map’s basic frame- work - though the next few decades will be spent improving its resolution, almost as if they were taking a pixelated digital image and sharpening the focus to reveal more and more detail.
By 2007, the workshop participants expected to triple the number of mapped genes and DNA markers, more thoroughly investigate the intricacies of gene expression, and add to the scaffold they now have, allowing for whole genome sequencing of the horse.
Already the Equine Genome Project
has yielded reams of valuable informa- tion. Some of it, for the Thoroughbred breeder, is merely of academic interest - the genetics of coat colour, for example (unless you’re producing sport-horse Thoroughbreds and are trying for homozygous black, or some of the new-fangled palomino, buckskin, or pinto models!). For the Paint or Appaloosa breeder, though, this is pivotal stuff · and not just for cosmetic reasons. We now know there are at least four different types of pinto colouration, from the genetic standpoint, and when the gene for one type, “frame overo”, is inherited from two parents, it can lead to a “lethal white” foal, an-all white baby tragically born without a good chunk of his digestive system. Thanks to DNA testing, ‘colour’ breeders can now test their stock for the frame overo gene and avoid producing that homozygous, unviable foal.
There are dozens of other genetic disorders which have also become far more predictable as a result of mapping the equine genome. In Arabians, there’s a condition called Severe Combined Immunodeficiency Syndrome (SCID), which leaves foals vulnerable to any tiny virus or bacterium in the atmosphere; most don’t live more than a month. Now
understood, breeders can
test their stallions and mares
to see if they carry the gene -
which is harmless in one
dose but deadly if both parents con- tribute a copy.
Likewise in Quarter Horses, geneticists have unlocked the secret behind HYPP (hyperkalemic periodic paralysis), a genetic mutation which traces back to one particular stallion. The American Quarter Horse Association requires testing of any animal with this stallion in its ancestry and mandates that the presence or absence of the gene be public knowledge, thus saving breeders from producing homozygous individuals who have an inability to process potassium and suffer muscle spasms and seizures as a result. In time, the AQHA hopes to eliminate the gene entirely from their gene pool.
Just as they get a handle on HYPP, Quarter Horse breeders are now contending with another genetic disorder, recently been identified. It goes by HERDA, for hereditary equine regional dermal asthenia, and once again, traces back to a single stallion. Horses with HERDA look normal at first glance, but their skin is poorly attached to the underlying dermal layers, and peels off their bodies in large strips, usually when the young- sters are first put into training. Breeders whose animals are from the bloodline in question have been asked to submit DNA samples, and the researchers investigating HERDA are in the process of contacting those whose horses tested positive as we speak.
There are also genetic disorders still under investigation -- ‘Lavender Foal Syndrome’, for instance. It’s a neurological disorder in Arabians which leaves newborns unable to stand
and nurse. The foals have a characteristic ‘ghostly purple’ coat. Only recently recognized and differentiated from perinatal asphyxia (lack of oxygen at birth) and spinal cord injury, it’s currently being investigated for its genetic source.
Genetic disorders have turned up in dozens of different breeds. In Peruvian Pasos, it’s degenerative suspensory ligament desmitis. In Rocky Mountain horses, there’s an inherited eye defect. In Belgians, a lethal skin disorder is carried by up to 35% of the registered individuals. And while Thoroughbreds have proven surprisingly free of these inherited defects so far, that may not be the case forever - especially in those individuals who are strongly linebred. We’ve known for centuries that the smaller the gene pool, the higher the risk. But there are those who continue to play Russian roulette · and we may eventually discover the bullet in the chamber.
On a more positive note, the Equine Genome Project has also triggered investigations of the genetic aspects of several common diseases - colic, laminitis, and obstructive airway disease among them. What they have in common is an inflammatory response, and a better understanding of how that works may help us find a way to flick the ‘off’ switch on overactive inflammation.
Genetic factors which predispose some horses to breaking down from musculoskeletal injuries, while others endure and keep running, are also being explored. In South Africa, a large study on the genetic markers for exercise-induced pulmonary haemorrhage (‘bleeding’) is underway.
And a joint study between Stanford University in the US and Uppsala University in Sweden is look- ing at the equine Y chromosome, which may hold secrets about stallion infertility. All of these endeavours will eventually yield important information about the genetics of performance, and allow us to produce racehorses designed for maximum soundness and health.
by Karen Briggs
Dave Landry Photo
TM
Preferred Sale Yearlings
#382 CIANO CAT X MOSELLA (LORD AT WAR) filly
Winning dam of seven horses of racing age, 6 to race,
5 winners. Dam is 1/2 sister to stakes winners and the dam of (G1) placed Barancella. Well conformed & typey individual. #459 PAYNES BAY X TUMBLING ACT (KIRIDASHI) colt First foal of the dam who is 1/2 to 2 stakes placed horses. Growthy colt with ground covering movement.
#452 PAYNES BAY X THE SPRINGS (WEKIVA SPRINGS) filly First foal of winning dam who is who is 1/2 sister to
SW Dawnelo, dam of stakes placed Dawn Watcher.
A large framed, correct filly.
#428 PAYNES BAY X SHAMANAGA (OUR NATIVE) colt Dam of 9 foals to race. Shamanuu (Regal Classic) set NTR at Hoosier Park - 6 furlongs 1:09.60. Solid, athletic colt.
HALES FARM
Lois Keays 519-534-5760 Wiarton, Ontario
email: loiskeays@msn.com