I was recently asked by a confused reader about what sort of link there is between skin color and hair color in hairless breeds. In breeds like the Chinese crested, it's not uncommon for a dog with dark skin to have pale hair. In other cases, the skin matches the hair. So, what causes this? To answer this, I'm going to look at a number of dogs and discuss the genes that are likely causing their hair and skin colors. First, though, some notes.
As a general rule, the darkest skin color should match the black pigmentation that would be seen in the coat. Patches of pink skin, whether spotted or not, represent what would be white markings on a dog with a full coat. By taking into account these characteristics, plus what's seen in whatever hair the dog happens to have, you can get a pretty good approximation of what genes are causing the dog's appearance.These rules don't always work, but I'll try to explain these exceptions.
this. Since this dog has so few spots, it probably doesn't have a copy of the ticking gene.
Siggy, whose skin spots overwhelm his red ticking spots because his fur is so thin.
matching the color of its nose to something like this. In dogs like this, the nose, eye rims, and paw pads would be dark, but the predominant skin color is actually pink. If there are any white markings on the dog, it would be difficult or maybe even impossible to tell. If this dog had fur, it would look kind of like this.
Isabella. I have actually heard of cresteds that are this sort of color being called palomino which is an...interesting way of looking at it. The genes behind horse color are completely different from those behind dog color, so those sorts of naming schemes don't make sense to me. Anyway, the fawn coloration doesn't just change a dog's coat color, but it also dilutes down the skin color. In combination with this, the dog is also expressing the recessive red gene. This explains why it has white hair. If this were not true, the hair would be similar in color to the skin,and the dog would look more like this.
Images are from Wikimedia Commons and Flickr.com under Creative Commons licenses: one, two, three, four, five, six.