Slania - there are somatic mutations, where the mutation occurs only in the somatic (non-reproductive) cells. This can cause a visible change, such as a patch of color that is different from the rest of the body. Then there are chimeras, where 2 embryo actually merge together to create one. In such an animal there would be genetic material from two different individuals. If that occurred involving the skin and fur cells, then you can see different patches of color. Neither of these are particularly common, and neither is genetically passed on to offspring either. Depending on how each individual is affected by their "condition" they may or may not be fertile to produce offspring.
