Impressive and HYPP question

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Impressive and HYPP question

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    05-18-2010, 07:29 PM
Impressive and HYPP question

I've been looking at AQHA horses for sale and I was under the impression that I should not buy any horse with Impressive in their bloodline due to HYPP. However, some of the horses I was looking at have him in their direct bloodline and are supposed to be N/N. Do all of his descendants carry the disease or can it skip a generation or something like that? Thanks for your help!
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    05-18-2010, 07:33 PM
Not all Impressive bred horses have HYPP.
    05-18-2010, 07:35 PM
Even if they are n/n, is it possible for them to pass it on to a foal? That's what I thought but I don't know much about AQHs.
    05-18-2010, 07:36 PM
In the new Quarter Horse magazine, it states that one parent with a single copy of the gene can pass it on and create an affected horse. DNA stesting for the gene mutation is performed by using mane and tail hairs.. A rule in AQHA states that all foals born on or after Jan.1, 2007 that are descendants of Impressive are required to be parentage verified and HYPP tested. Any foals testing homozygous positive for the disease are not eligible for AQHA registration. So, if the horses you are looking at have been tested are N/N that means their parents are verified and the horse is not a carrier of the HYPP
    05-18-2010, 07:41 PM
The article goes on to state that only 1.5 % of QH are affected, yet 60% of Impressive descended halter horse are affected. If I was looking at horses that had Impressive and they were older than 2007,I would make sure you see paperwork that the parents were tested and clear. If they can't show paperwork that the parents were tested or that the horse I am interested in is definetely N/N. It is mostly in halter horses, not too many Impressive bloodlines in performance anymore.
I myself would not buy one with Impressive bloodlines
    05-18-2010, 07:42 PM
N/N- Does not carry and is not effected with HYPP
N/H- Half the foals will be N/H
H/H- All foals will be N/H or H/H

Just make sure the horse your buying with Impressive on his papers/bloodlines be tested for HYPP, and will be tested N/N.

I would personaly never buy a horse that is N/H or H/H as there symtoms can come back at any time, even if they never shown them before.
    05-18-2010, 07:42 PM
Ok, thank you so much for clearing that up! It was getting a bit confusing searching by myself.
    05-18-2010, 07:44 PM
The HYPP gene follows basic mendelian inheritance.

Each horse has two copies of the HYPP gene. They are either positive, H, or negative, N, for the disease. They get one from their sire and one from their dam.

H/H horses have the disease and will always pass the gene on to their offspring.

N/H horses have a 50% chance of passing the gene on to their offspring. I've seen differing opinions on how safe and healthy these horses are.

N/N horses do not have the disease as they are not positive for the gene at all. They cannot pass it on to their offspring as they do not have it themselves.

Now, the foal gets one gene from each of its parents, so the only way to be sure your foal will not have HYPP is to breed two N/N horses. If both horses are N/N then there is no way the foal can have HYPP, but if one of the parents is N/H, even if they haven't shown any symptoms, they can pass the gene and the disease on.
    05-18-2010, 07:47 PM
Too bad so many Impressive foal and descendents were born before they realized he had such a horrible genetic disease. I know of a young stallion that was a direct son of Impressive. Man, he was gorgeous and threw some beautiful colts, then the HYPP came out in public and he was gelded. He did not show signs of HYPP, but did throw some HYPP foals, so obviously he was a carrier.
Very sad they did not know about HYPP before so many ended up with it. If you figure how many Impressive foals and descendents were born and 60% had HYPP, that's a huge number...
    05-18-2010, 11:09 PM
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*warning - Rant* I have 2 impressive horses. Both are HYPP/NN. I think they are great horses. It makes me sad that everytime the name Impressive comes up, people insist on dimming the light on him. Yes HYPP is a horrible thing and it's a very sad thing that people didn't know about it. He was heavily bred, yes, but so is every other great stallion out there.

HYPP is something that should always be known. People should understand it, just as they should understand such things as HERDA in quarter horses, SCID, CCA, LFS, OAAM, Epilepsy, and GPT in arabs, you also have LWS, OLWS, WFS, and wobblers syndrom in Paints. You have Saddlebreds, who have some sort of defect but I can't think of it. There are also Miniatures that have dwarfism, Appys have the highest risk of ERU and CSNB (blindness type issues), and belgians have an issue to....

So all breeds have their demons....We should become more knowledgeable yes, but not condem a horse for it's lineage...

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