Quote:
Originally Posted by Terri_R
Basing this question purely on my own limited experience of breeding a palamino paint mare and a grey mare to a black and white paint stud....do paint studs always produce painted foals? Both of ours turned out to be paints but I didn't know if that was the norm or not. Just curious to know other's experience.
Way late into this discussion but here goes.......
There are three "overo" patterns in Paints/Pintos.....one of them, the frame overo pattern, can produce what is called "lethal white" foals. There is a test for horses that might have this gene called the OLWS test (overo lethal white syndrome). Not all horses that look like frames really are and horses that don't LOOK like a frame CAN carry this gene....even solids. The problem is when an OLWS positive horse is bred to another...you have a one in four chance of a lethal white foal. These foals are usually but not always totally white, are often born dead or they will die within a couple days. The problem is an incompletely developed gut...it is either a blind end from either end or lacks the nerves to make the gut work so the foal cannot pass food/wastes through and dies of what looks like colic. An OLWS positive horse should not be bred to another so if you have a mare that is positive check the tests on any stallion considered for her....and if you have an OLWS positive stallion you probably ought to refuse to breed to positive mares.
The other two "overo" patterns, sabino and splash white, can both be bred together without problems...with one minor (to the horse) exception. Splash white horses that have big bald faces (usually with a flat upper edge to the face markings) that goes close to or actually reaches the ear base can sometimes be deaf. This doesn't appear to be a problem for the horse but some owners find it a problem for them. The well known Paint/QH reining stallion Gunner is reportedly deaf as a fence post and in some ways this can be an advantage (no spooking from noises!).
None of the overo patterns is clearly a dominant gene...frame can exist in QH's and TB's without showing at all for instance as can splash and sabino (although you can often see hints that these are present if you know what to look for in the "normal" white markings). Splash white and sabino can also be homozygous (the horse has two genes for this pattern.....heterozygous means he has one for the pattern and one for solid coloring) while homozygous frame is a lethal white foal.
Tobiano is a totally different genetic pattern. It is a dominant gene meaning that it takes only one gene for the pattern to show. A tobiano may also have one or more of the overo genes (they are at different locations on the chromosome so don't block each other out) and may show them or not...if he shows a combination of tobiano and overo he's called a tovero or tobi-overo and can pass any one of them or all of them to his foals. Homozygous tobiano horses will have two tobiano genes (and may still have one or more overo genes as well) and will always pass one to his foals so that his foals (or hers if a mare) will have at least the tobiano pattern of markings. Since tobiano horses can also carry any of the overo patterns it is still a good idea to have them tested for OLWS...it can hide in what appears to be a totally tobiano horse and you can get a lethal white foal if this is the case in both sire and dam. Tobiano does NOT eliminate the potential for OLWS as many tobiano horses were crosses with various overo patterns to increase the production of color while also decreasing the chances for OLWS. Unfortunately this means that even tobi to tobi breedings can give a lethal white result.
I breed performance bred tobiano pattern Paints and am fortunate to have several homozygous tobiano mares and a new young stallion that is also homozygous for tobiano. If I breed the HZ stallion to any of my mares (including the few QH mares here) I will get a colored foal. If the mare is solid the foal will be heterozygous (one tobiano gene one solid gene). If the mare is heterozygous for tobiano the foal will be tobiano as well and will have a 50/50 chance of being homozygous itself. If the mare is homozygous all foals will inherit one tobi gene from her and one from the stallion and be HZ themselves.
If you breed to a HZ tobiano stallion you will always get a tobiano or tovero foal. Be aware that a gray mare may be heterozygous or homozygous for gray and that if she passes the gray gene to her foal the foal will become gray and loose the colored hair in the Paint pattern....the pigmented skin will still be there and will sometimes be easy to see and sometimes only shows well when the horse is wet.
Do Stud Paints Always Produce Painted Foals?
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