I thought If I made a mini series of info on Horse whites for LOUHD
that it would be helpful. I wanted to make a better one than that one I made the other day, (Which I deleted) that was more helpful with pictures. I plan to eventually make a sheet for the LP gene, but for now we have this one! it covers the Tobiano and Overo strings.
Lethal Splashed White
Info from Animal Genetics, Inc. (www.animalgenetics.us)"Research suggests that the SW-1 allele arose several hundred years ago before the foundation of the modern horse breeds. Breed distribution of SW-1 includes Quarter Horse, Paint, Trakehner, Miniature Horse, Shetland Pony and Icelandic Horse and may be present in other breeds as well. Horses homozygous for SW-1 (SW1/SW1) have been identified, which suggests that this mutation is not homozygous lethal. Research also suggests that SW-2 and the rare SW-3 may only occur in certain lines of Quarter Horses and Paints. It is also speculated that SW-2 and SW-3 may be homozygous (two copies of the mutation) lethal and result in non nonviable embryos. It is there for not advisable to breed two horses that carry SW-2 or SW-3 as the risk of a nonviable embryo could be 25% and should be avoided. "
Simplified Translation: Horses homo for SW-1 are not lethal but horses carrying SW-2 or SW-3 when bred if foal resulting is homozygous for either will be lethal white foal similar to the O/O genes.
I see this commonly, this is in todays horse world extremely
outdated. This simply means "A horse that's Tobiano and some other Overo gene we don't care about" which can be dangerous if that other Overo you don't care about ends up being frame, and in a breeding situations that can result in a Lethal White Foal. So proper wording of this is to say (in example)
"Hes a Chestnut Tobiano that also Carries ________ (insert Overo Gene here- so either Frame, Splash, or Sabino)
Disclaimer: I am not telling you how to Geneotype or Phenotype your horses! This is just some science, your choice if you want to follow it, I could care less! it's a pretend horse.
Sheet (c) me [Jechoe
Photographs (c) Their owners.