The gene that determines the Appaloosa characteristics (Ap) is dominant. You will know the dominant gene is present, even if on only ONE side of the chromosome, because it will be expressed (visible to the eye) in the outward appearance of the animal. All Appaloosa horses with coat pattern and/or parti-colored skin will have the Appaloosa color-producing gene (Ap) on at least one side of the chromosome such as in Figure A.

Figure A

ap | Ap

When the Figure A horse is mated, half of its genetic material will pass to its offspring....either the Appaloosa color-producing gene (Ap) or the non-producing gene (ap). If this horse were mated to another Appaloosa with like genetic make-up for the color-producing gene, there are then four possibilities as to the genetic make-up of their offspring.

Figure #1						Figure #2
Sire ap|Ap				Dam ap|Ap		Sire Ap|ap				Dam Ap|ap
		Resulting Foal ap|Ap						Resulting Foal Ap|ap
This foal has inherited the dominant producing gene from its Dam and is on only one side of the chromosome. This foal IS an Appaloosa and will be visibly recognized as an Appaloosa.						This foal has inherited the dominant producing gene from its Sire and is on only one side of the chromosome. This foal IS an Appaloosa and will be visibly recognized as an Appaloosa.

Figure #3						Figure #4
Sire ap|Ap				Dam Ap|ap		Sire Ap|ap				Dam ap|Ap
		Resulting Foal ap|ap						Resulting Foal Ap|Ap
This foal has inherited the Non-Appaloosa producing gene from each of its parents and this gene is on both sides of the chromosome. This foal is NOT an Appaloosa. It does not have the dominant Appaloosa characteristic producing gene and therefore cannot pass it on to its offspring.						This foal has inherited the dominant Appaloosa producing gene from both the Dam and Sire. It has the dominant Appaloosa producing gene on both sides of the chromosome. This foal IS an Appaloosa and will be visibly recognized as an Appaloosa. In addition, every foal this horse produces will BE an Appaloosa as it ONLY has the Appaloosa producing gene to pass on to its offspring. This is what we call totally dominant and consider PURE!

You will note that each Appaloosa foal has at least one dominant Ap color producing gene in its genetic make-up. These foals will have coat pattern or design and/or characteristics. The degree of color may vary, but they ARE APPALOOSAS!

The Figure #3 foal is not an Appaloosa even though both parents were Appaloosa and could have descended from many generations of Appaloosas. This non-Appaloosa foal does not carry the color-producing (Ap) gene, instead it has a pair of non-color-producing (ap) genes. This horse would be a solid color with no characteristics and no color-producing gene to pass on to its offspring. To breed two such horses would only result in producing solid, non-characteristic foals. If it does not have the characteristics of an Appaloosa, cannot produce an Appaloosa, it is NOT an Appaloosa. Out-cross horses of other solid-colored breeds would also fall into this classification.

Should the color producing gene be on both sides of the chromosome as in Figure #4, this would be what we call totally dominant and consider pure. Every foal this horse produces would be an Appaloosa no matter what breed it was bred to, it has ONLY the color producing gene to pass on to its offspring.

Copyright © Cecil A. Dobbin. All rights reserved.

This article first appeared on the world wide web in February 2000 at URL:   barnlot.tripod.com

Joe Daniels