There are some registries that accept horses (and sometimes ponies and mules) of almost any breed or type for registration. Color is either the only criterion for registration or the primary criterion.
These are called color breeds, because unlike “true” horse breeds, there are few other physical requirements, nor is the stud book limited in any fashion.
As a general rule, the color also does not always breed on (in some cases due to genetic impossibility), and offspring without the stated color are usually not eligible for recording with the color breed registry.
There are breeds that have color that usually breeds "true" as well as distinctive physical characteristics and a limited stud book. These horses are true breeds that have a preferred color, not color breeds, and include the Friesian horse, the Cleveland Bay, the Appaloosa, and the American Paint Horse.
The best-known "color breed" registries that accept horses from many different breeds are for the following colors:
- Buckskin (horse), a color which cannot breed "true" due to the cream gene which creates it being an incomplete dominant
- Palomino, a color which cannot breed "true" due to the cream gene which creates it being an incomplete dominant
- Pinto horse.
- White horse. Some of these animals are registered in the United States with the American creme and white horse registry, which was once called an "Albino" registry until it was understood that true albino does not exist in horses.