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csziggy

(34,119 posts)
15. Forgot to say - AQHA was very much stirred up by the situation
Sun Jul 5, 2020, 12:51 PM
Jul 2020

The genetic disease was traced directly to the offspring of a very popular stallion whose owners demanded very high stud fees for breeding. Then his sons also charged very high stud fees. In the 1980s I was just getting into breeding Quarter Horses but I did not like the conformation (way the horse was built) and avoided breeding to him or his descendants.

Then it came out that this very serious metabolic disease was confirm as coming from the stallion:

HYPP and the Impressive line of American Quarter Horses: The facts

News News | May 23, 2012
Jan Swan Wood

In 1969, an American Quarter Horse foal was born that changed the history of the halter horse in three breed registries. Born with outstanding conformation, disposition and pedigree, the colt named Impressive, eventually set the standard in halter horses for the Quarter Horse, Paint and Appaloosa breeds.

Sadly, because he was the biggest name in the halter world, he and his offspring were used extensively for breeding, and when a devastating genetic defect was isolated, it had already affected tens of thousands of horses. The “Impressive” line, once noted for their exceptional halter conformation, became known as the hyperkalemic periodic paralysis (HYPP) line of horses.

In 1992, researchers designated the Impressive line of horses as carriers. Not all horses of that line had HYPP, but all horses with HYPP were descended from Impressive himself. In 1994, a genetic test that utilized DNA from hair or blood, was perfected, this determined whether a horse had HYPP or not.

Hyperkalemic periodic paralysis is a genetic disorder that causes horses to have episodes of muscle spasms, weakness, “dog sitting” due to hind quarter weakness, collapse, recumbency, sweating, high serum potassium levels, third eyelid twitching and yawning. Levels of distress during an attack vary, with some horses showing only mild symptoms, while others have very severe symptoms. Due to respiratory paralysis or respiratory failure during an attack, some horses can suffocate and die.

More: https://www.tsln.com/news/hypp-and-the-impressive-line-of-american-quarter-horses-the-facts/


Of course, now it is accepted and the science is better understood. All this came down in the early 1990s when DNA testing was very new and not well trusted, though the rumors about problems with Impressive offspring began years earlier.

Even recently people are still affected by the problem - while in the UK last fall I met some people whose daughter had a Quarter Horse that had this condition. The sire had been imported into England - I suspect that he had tested positive and AQHA refused to allow his offspring to be registered in the US, so he was taken to England where registration documents are not as important and bred there. I consider that to be an immoral act, especially to not disclose this possibility to the mare owners they got money from.

In the case I encountered, the horse had been donated to a group that only used it for light work, since it could not tolerate the type of showing the daughter wanted to do. The family was out thousands of dollars and had the heartache of having to get rid of a horse they all loved.
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