LWO Testing? Where and whats involved

[kitcat0601]

Well, im gonna rip some tail hairs out and do the LWO and Sabino testing. Its cheap enough and definatly something I need to know. Thats true, I would just have to be responsible with breeding. No Impressive bloodlines so I dont need to worry about that thank God. Thanks for the input. Much appreciated.

[bndranch]

On that note MOST places want mane hair NOT tail hair. Only time they say send tail hair is for tiny foals. Just a little FYI!

[kitcat0601]

Mane hair would be much easier to pull than tail hair. I checked animal genetics website and they said mane or tail hair. Not sure what UC Davis says. Thanks for the info.

[emma]

Hi,
Sorry if I am intruding on anything that may have been discussed already and that I missed.

Not necessary to test that colt for Frame overo in my opinion. He carries it and he looks the part. The overwhelming majority of living frame overos carry ONE copy of the frame overo gene (they are N/O for overo). It´s what's making them colored like this, and is not a problem for the individual. However, and I agree on that, they are tested for one specific gene location. If the coloration is linked to anywhere else, it would not show up on the test, and maybe not cause lethal white. In testing, you do not look at the complete genetic make-up, nor are all genes and effects researched.

The issue lies in breeding two horses that BOTH carry the frame overo gene. If the foal gets the frame overo gene from BOTH father and mother, it will carry two copies of frame overo (O/O) and be a lethal white (LWO - Lethal white overo syndrome) foal. The risk as the poster before me also said, lies in breeding two frame overo colored horses together, not in the horse itself.

And since frame overos with two frame genes (lethal whites) are homozygous that don´t survive, your chance for frame coloration stays untouched at 50% chance for color, regardless of the mating. The decision that you are making in your breeding is actually whether it´s 50% color/50% solid, but alive foals or if you get 50% color, 25% solid, and a 25% chance of a lethal white foal.

It is also true that not all horses carrying frame overo look on the outside like they do, so it´s great to have them tested. But your horse also looks like it, and he very likely will test positive for the overo gene.

About roan:

The problem in the horse world that roan means "white hair intermingled with any color basecoat". As such there is more than one horse color that can and IS called roan, but it´s not the same genetically.

There is "going grey" roan

Appaloosa type roaning (hips and other prominent bony structures stay colored, rest whitens)

True roan (changes with season, in Summer head legs and long hair stay unchanged dark, rest whitens)

Sabino type roan (large amount of white on face, legs, sometimes body, white hair on edges)

Rabicano type roan (coon tail, sometimes, white hairs in flank area)

Now all of them are used - and all of them have the potential to create confusion. Also, because they have been interbred, a horse may or may not carry and display more than one type of "roan".


What´s called "lethal roan" is breeding two horses of the type that I named "true roan" together. There is a marked decline in pregancy rates in such cases, and the suspicion is, that a it can sometimes cause in incompatibility that results in death and early absorption of the fetus. The mares comes back up open after a few months. With scientific evidence still on the way, some say yes, true, other no, false. Does not apply to sabino roan.

Hope this helps,
Emma

[kitcat0601]

Your not intruding, but giving your knowledge which is great. Neither parent carries the gene and the sire hasnt thrown any lethal white babies. I spoke with his breeder. Not saying this is 100% accurate. The reason for testing him would to be a responsible person if I decide to stand him at stud. If someone wants to know his status I would rather not say "I dont know". That would not be a very professional answer in my opinion. Alot of breeders have stallions that carry the gene but leave it up to the mare owner to take the chance on a Lethal foal. Its a sad shame, but its done. The test is 25.00, so it wont break my pocketbook and would be the right thing to do I think. I understand what color roan is and have found some great websites that have explained everything you listed. Genetics are facinating arent they? Thanks Emma for the input and I will let you know what his test results are when I get it done. Hes only a yearling, so no rush.

[emma]

Hi,
Yes, Genetics are really fascinating. Glad you found research material. I know I am never done learning either. That´s a very broad based subject. If it´s that cheap to test, it is certainly a responsible thing to do.
Are the parents both tested for LWO?
(As we have discussed before, sometimes it is not possible to tell by looks alone). Not having thrown an LWO foal isn´t proof. Might just be luck, or that very rare genetic exception, but the test is certainly a start to assessing the status of your colt.

Emma

[ccpainthorses]

Ok, this may be an old topic here, but I wanted to also mention that they are finding LWO in more than just paint breeds. Think of all the breeding stock paints registered also with different associations. I have done years of research on this (since purchasing our stallion years ago) and it is coming up more and more that it is found in different breeds, patterns, and I will try and find the link so that many can see this for themselves, I know I had to, they have had some tobiano horses produce LWO foals. Again, I will find the post and make it available, I don't want to stir the pot here.

I would recomend testing your horse reguardless of his looks. Yes he does appear to have it, almost a spitting image of our boy in markings btw. I can only say that any horse that has the remote possibility of having overo lineage should be tested. Test your mares, test your foals, have the information available to outside mare owners, talk about it, tell the potiential foal owners about it, get it out there so that all of the misconseptions can be stoped. I didn't think this in the beginning, but over the years our views have changed. Being a paint breeder we test EVERY mare and foal, it would be irresponsible not to in our opinion, and yes, we breed overos, I'm just so partial to their markings. Little cutie patoties!!

[kitcat0601]

Oh, I know CC, about the Tobi or Tovero carrying the gene. If there are any overo parents in a horses pedigree they can carry it. My trainer who breeds paints was telling me about it. Definatly getting him tested. Being sabino would be a plus as I believe its a desirable trait. And quite pretty as well. I cant believe there are so many things to be carefull for when breeding any horse. HERDA, HYPP, LWO. I wouldnt worry too much about testing my mare's since one is a foundation quarter horse and the other is a TB, but would want to know about the resulting foal's status as I think it is important. I would love to see the post your talking about. I find it all informative. Thanks, Cathie

[angelakane]

I guess the way I look at it is that what harm is it going to do to test? Regardless of the outcome it makes you a more knowledgeable breeder/owner and that is NEVER a bad thing. Besides, who knows down the line what could happen with future offspring or with genetics. It could happen that there is a fatal genetic disorder that has yet to be discovered that may link back to something they don't currently know about different genotypes.

I just think it is a good thing to have genetic testing done (Especially with how affordable it is) regardless of whether you suspect him/her to be a carrier of some disease or disorder.

[emma]

Hi,
"Roan" is always a hard color to discuss, as there are so many colorations in the horseworld, which are all named roan, without being the same genetically.

The term "lethal roans" has been in discussion for a while as when you breed two true roans (no excessive white hair on head and legs except markings; silvery hair in body color, changing colors with seasons), there seemed to be a lower conception rate. It is scientifically unclear, if there is a "lethal roan", and it´s not proven that roan homozygousity (double copies of the roan gene) cause any harm in the foal.

Also, if they exist those "lethal roan" babies are not born, the theory always was that they die and are reabsorbed early in the pregnancy. You´ll never have a living, breathing "lethal roan", just an open mare again.

Apart from the many things that can go wrong early in the pregancy, I feel newer reasearch is fairly certain to have found "double roans" with no ill side effects attached, which would make the worry about lethal roans moot.

Emma