What is lethal white?

bubba13 · 09-21-2011, 05:04 PM

Quote:

Originally Posted by Corporal

alforddm, I appreciate that. I'm not looking to offend ANYONE. I do, however notice an increase in health problems in horses that are the result of breeding to a type or a color--it's a current trend. I'm not referring to an upright shoulder, or a straight leg or a weak back, but I think "lethal" white says it all. I just don't want anybody to breed a horse (or dog) that isn't healthy bc of the genetic mix that they intentionally choose. I guess you could say that I "campaign" against this.
I have talked to a lot of horse people, many who sternly maintain that it will be okay to breed this or that, understanding that there are documented health problems, bc they've found one specimin that didn't have it. I'll tell you, one time was enough for me. Here is a picture of my QH gelding, "Dandy Silver Moon."

1987
He was a gorgeous cremmelo, great attitude and willing. He went blind at age 7. I, for one, will not EVER buy another cremmelo. I understand it's referred to as an "Isabella Palomino," and you can make out his blaze, in contrast to a dappled, ivory coat. I was stunned when my Vet discovered his sight problem, but he told me the defect was genetic. Even IF it only happens periodically, I do not think breeding this improves these horses. Again, I am sorry to offend anyone but I get very attached to my horses, and I cannot afford to keep one crippled by a genetic defect as a pasture-pet. OP, Please consider outcrossing your mare for the color you want.

In the picture, which I realize could be misleading, that appears to be a pale palomino, not a cremello. But neither color is associated with eye or blindness issues. Correlation does not equal causation, and to refuse another horse of that color (no matter which) is, no pun intended, extremely short-sighted.

It's not a sign of inbreeding or man-manipulated genetics, either. Appaloosas actually are very much prone to a myriad of serious eye issues, yet their pattern has existed in the wild for millenia.

Dreamcatcher Arabians · 09-21-2011, 06:16 PM

Quote:

Originally Posted by jannette

bred back to a frame she is b/w frame...i new nothing when we baught her. Now all we can do is x our fingers...not cool. Breeder didnt say a word. I found out here on the forum

Breeder's who do these things and do not disclose are the scum of the earth. Notice they sold the mare on so that if the foal is OLWS and dies THEY don't have to deal with the heartache! That just burns me right up. It's wrong on so many levels I can't even start to enumerate them. I'm sorry someone did this to you, without making sure you had all the info you needed to make an informed decision.

jannette · 09-21-2011, 07:32 PM

Thanx dreamcatcher, I was raging mad when I found out

....she informed us she has been in business for years and never had problem blablabla...she offerd to buy mare back but she's great girl and I wont do that to her regardless, not her fault. She has good home now....and I make sure anyone I know, knows what her practice is. My horses are more then livestock theyre my babies so im just hoping for the best

CessBee · 09-22-2011, 03:04 AM

Ok, I am making the assumption here that LW must be found very near the gene loci of the colouring that is associated with. That would explain why it is possible for there to be solid coloured horses which carry the mutation.

I like genetics haha and am just spit balling ideas here.

It is not as bad as HYPP because of the fact that if the horse is homozygous for the gene it is dead, unlike with HYPP which if I am not mistaken can have hidden symptoms which do not show up. And is easily managed if the right precautions and study is done before the breeding takes place.

Day Mares · 09-22-2011, 03:15 AM

Okay. Now I have to go look up HYPP, unless anyone wants to enlighten me?

blue eyed pony · 09-22-2011, 03:25 AM

I don't know a huge amount about it but it is a genetic problem with the muscles that can cause seizures. It's been traced back to the stallion Impressive. It's believed to be incomplete dominant which means that if a horse has one copy of the gene it is still affected, but if it has two copies it is MUCH more seriously affected.

Responsible breeders and QH/paint associations around the world are trying to stamp it out without losing the bloodline as it consistently seems to breed a highly desirable type.

I actually don't know what HYPP stands for though :\ probably some really technical scientific thing that makes no sense to most people anyway.

Poseidon · 09-22-2011, 03:47 AM

Hyperkalemic Periodic Paralysis
Horse HYPP

I can't remember because it's almost 3am, but I think the AQHA requires a horse to be tested before registered if it has Impressive lines. If the world were truly a perfect place, people would only be breeding N/N horses and the disease would be bred out. However, they don't. There was a catalogue of QHs in the office at my barn. The cover had 6 foals on it, two were N/H. On the cover. It seems that they try to justify breeding N/H horses because some don't obviously show symptoms of being affected.

alforddm · 09-22-2011, 08:53 AM

Quote:

Ok, I am making the assumption here that LW must be found very near the gene loci of the colouring that is associated with. That would explain why it is possible for there to be solid coloured horses which carry the mutation.

No, frame is located on EDNRB which is also responsible for Waardenburg Syndrome in humans which is known for white patches of skin as well as other more significant problems.

Every other white pattern can also be found in minimal form. This thread as some pictures of some VERY minimal tested Tobianos.
Check out this tobi tail! | Equine Color Genetics

bubba13 · 09-22-2011, 09:06 AM

The frame gene IS the lethal gene. They are one and the same. And frame is not the only white pattern that is lethal in the homozygous form. All the variants of dominant white are, as well.

alforddm · 09-22-2011, 09:13 AM

Quote:

Originally Posted by bubba13

The frame gene IS the lethal gene. They are one and the same. And frame is not the only white pattern that is lethal in the homozygous form. All the variants of dominant white are, as well.

This is indeed correct. The difference, for those who may not know, is that DW is embryonic lethal very early in the pregnancy with the mare generally being able to be re-bred the same season. It doesn't result in a live foal that dies soon after birth.

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