There’s a common trend among domesticated animals—they tend to develop more variegated coloring than their wild ancestors.

One theory is that domestication affects traits that involve early embryonic development, and that have a lot of associated changes beyond what was actually selected for (i.e. tameness).

Another possibility is that, in the absence of selection, animals naturally produce more variation in coloration than is seen in the wild—but natural selection is continually weeding out those that are disadvantageous in their current environment.