Paint and Pinto Genetics, continued ...
Paints and Pintos can carry several of these alleles at once.
This makes it more likely that their offspring will be spotted.
A tovero (tobiano plus any of the overo alleles), if bred to
a solid color horse, will give at least 75% spotted foals. A
Paint or Pinto that is almost solid white also usually carries
two or more color alleles, and can give 75% or more spotted foals.
Background color makes a difference. As noted above, the alleles
for spots occasionally throw so little white that you can only
register your foal as breeding stock. However, sorrels consistently
have offspring with a greater area of white than do bays, and
bays have more white than blacks.
Your Best Breeding Bets
Your chances will be equally good breeding to a homozygous
sorrel tobiano, or to the solid white offspring of splashed white
sorrel parents. A Medicine Hat stallion with sorrel ears would
be nearly as good, followed by Medicine Hat with any other ear
color. You will get at least a 75% chance breeding to a tovero.
Veterinary Genetics Laboratory at the University of California
Test for the frame overo allele: http://www.vgl.ucdavis.edu/research/coats.html.
Test for homozygous tobiano alleles: http://www.vgl.ucdavis.edu/service/horse/tobiano.html.
Overo Lethal White Syndrome Update: http://www.thehorse.com/viewarticle.asp?fid=2911&dpt=5.
Carolyn M. Bertin is a science writer and former horse
trader who lives in Sandia Park, NM.
Equine Color Genetics, by D. Phillip Sponenberg,
2nd ed. (Iowa State Press, 2003)