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Impressive: A tale of triumph and tradgedy

Impressive was born on the 15th April 1968 (and on the first birthday of the authors brother!). A chestnut Appendix American Quarter Horse colt foal, with royal Thoroughbred breeding on both sides of his pedigree. He was set to become one of the most famous and successful quarter horses in history.

Impressive changed hands a number of times, his price rising at each new sale. Dean Landers purchased him for $20,000 at the Indiana State Fair and showed him for a while, along with his other famous halter stallions Two Eyed Jack, Coy's Bonanza, and Sonny Dee Bar. After just three months he sold him to Fennel Brown for $40,000, who raced him. Unfortunately he was soon excluded from racing and other performance disciplines due to pedal osteitis. Returning to the halter ring he lived up to his name, winning 31 blue ribbons out of 31 attempts (UK readers note that the blue ribbon is the winning one in the USA). Then in 1974, at age six, he became the first World Champion Open Aged halter stallion, with 48 halter points. Brown was offered $300,000 for him but refused the offer, apparently saying that there "ain't nobody in this world got enough money to buy this horse."!

Impressive was in demand as a sire, popular for his muscular and refined form, he turned out one champion after another, siring almost 30 World Champions! Even though at one time his stud fee was a staggering $25,000 he eventually fathered about 2,250 foals, including Noble Tradition, a four-times World Champion halter stallion and a highly successful sire in his own right. He was at least the number 5 all-time leading quarter horse sire when ranked by AQHA points earned by all his progeny combined. In 1992 13 of the top 15 halter horse, were descendants of this amazing horse. In 1993 he was estimated to have in excess of 55,000 living descendants, including Quarter Horses, Paints and Appaloosas. He died on the 20th March 1995, at the age of twenty-seven. Although he died, he is not forgotten, and is now estimated to have over 100,000 living descendants!

It seemed that Impressive would go down in history as one hell of a horse: Impressive by name, impressive by nature! And then tragedy struck when Impressive was linked to something altogether more sinister: his genetic legacy included a genetic mutation recently implicated in the rare muscular disorder known as known as hyperkalemic periodic paralysis (HYPP). Although he never exhibited symptoms of the disease himself it gradually it became evident that many of his descendants were inflicted with the painful, alarming and often fatal disease. The disorder has never been observed in horses of other lineages.

As Impressive ascended to the top of the sire's list owners of his foals began to notice a strange muscular twitching that often left their horses temporarily unable to move. These episodes, which varied widely in degree and duration, were usually mis-diagnosed as tying-up syndrome or colic, but they are now known to be caused by hyperkalemic periodic paralysis. At the time Impressive's descendants continued to make history in the show ring and as breeding stock, some making their owners large amounts of money. It hadn't been proved that the disorder was exclusive to the hie line, and no one wanted to be the first to publicly implicate the Impressive as the source of HYPP, even though many people now know it by its' common name of Impressive Syndrome. As more became known about HYPP (due to research funded by the AQHA and the University of California-Davis Equine Research Laboratory) medication and a low-potassium diet were used to control it, lessening the frequency and severity of attacks. Many owners of affected horses considered HYPP an inconvenience, not a reason to refrain from showing and breeding their valuable horses. Most quarter horse owners were still unaware of HYPP.

Finally molecular genetics research identified the gene involved in HYPP, and a test was developed to show which horses carried the gene, thus reducing the moral and ethical burdens associated with identifying Impressive as the carrier. Nevertheless neither the AQHA nor the research community was eager to reveal the truth, fearing the possible legal and financial consequences as a wealthy sector of the horse industry was sent into turmoil.

During the past few years the pressure built to reveal the extent and nature of HYPP, and to eliminate HYPP by selective breeding. A genetic test was made available to horse breeders in 1992, and can identify affected horses with virtual certainty. The simple blood test is available at the University of California at Davis School of Veterinary Medicine, Department of Medicine, or through the AQHA. Breeders were pressurised to show that their Impressive bred horses were negative for HYPP, or to remove them from breeding. The lucky ones protect their investments by advertising their negative test results along with their stud services and sales. If you are considering buying a horse with Impressive bloodlines, whether for breeding or not, you would be wise to ensure that the horse is HYPP negative before committing to buy. This is true whether the horse is a pure-bred quarter horse or only part-bred.

At the AQHA 2004 convention a motion was passed to set January 1st 2007 as the date after which foals testing homozygous for HYPP would no longer be registrable, with mandatory testing for HYPP for the descendants of Impressive. The Appaloosa Association followed suit and will disallow the registry of homozygous foals from January 1st 2008. The American Palomino registries have gone all the way and passed rulings against both homozygous and heterozygous HYPP horses, also beginning on January 1st 2007. Part and half-blood registries need to follow suit and pass rulings on both testing and registration. If enough pressure is brought to bear it might eventually be possible to eliminate this awful disease from the horse population, so that Impressive may be remembered for his impressive legacy rather than his infamous one.