Appaloosa coat patterns are modifying patterns, just like gray and true roan; these “modify” the base coat. In all of these cases, the horse has a base color. In the case of an Appaloosa, this can be black, bay, chestnut, dark bay/brown, palomino, dun, black, cremello/perlino, buckskin or grulla.

The Appaloosa Horse Club (ApHC) recognizes 13 base coat colors: bay, dark bay/brown, black, buckskin, grulla, dun, palomino, cremello/perlino, chestnut, gray, bay roan, blue roan, and red roan. The following are representations of each color, reprinted by permission from the ApHC, with the exception of the Cremello/Perlino base coat.

Solid Appaloosa horses are not to be confused with gray horses, which display a similar mottling called "fleabitten gray". As they age, "fleabitten" grays may develop pigmented speckles in addition to a white coat.

There are two classifications of appaloosa- coloration and breed. Color-wise, your horse is gray. Gray will cover any base color/pattern he was originally, though it doesn't sound like he inherited any of the appaloosa characteristics anyway.

Appaloosa. Appaloosa is both a horse breed and a color. You’ve likely seen an Appaloosa before—they’re notable for their beautiful spots. While a registered Appaloosa will almost always have the distinctive spots, other breeds can occasionally display Appaloosa markings (although it is very rare).