Paint and Pinto Genetics, continued ...

Combination Patterns

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

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.

Resources:

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.

Equine Color Genetics, by D. Phillip Sponenberg, 2nd ed. (Iowa State Press, 2003)

Carolyn M. Bertin is a science writer and former horse trader who lives in Sandia Park, NM.

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