Sometimes animals, and people too, are born with something called albinism. This means that they don't have pigment in their skin, hair, and eyes. They may be missing this pigment all over their bodies or just in certain places. And the reason they don't have this pigment is because they don't have the enzyme that makes melanin. Or if they do have this enzyme, it's not working the way it's supposed to.
Okay, well, that's a really, really simple explanation of the science that makes albinos. I don't understand all the details, but what I do understand is that you can inherit albinism through your genes, but it is very rare. And if you have it, there is more of a chance that you will get skin cancer because you don't have any pigment in your skin to protect you from the nasty UV sun rays that cause cancer. And also you might have some eye problems.
If a wild animal is an albino, that animal doesn't have a very good chance of hiding from its predators because it is white, and this means it probably won't live very long. But albinos that are domestic animals or that are in zoos can live a long life, just like regular-colored animals.
The eyes of albino animals look red or pink because there is no pigment in the eye, which means that you can see the blood vessels inside the eye. A partial albino will have blue eyes because there is a little bit of pigment. Also some partial albinos look like piebalds because their white patches are just here and there, instead of all over their bodies.
Albino dogs are pretty rare, just like albinos of other kinds of animals. Lots of dogs are white, but very few of these are true albinos. So how can you tell if a dog is an albino? Well, first of all, the dog will have a nose that is light pink. It is even lighter pink than a pig's nose. Also the dog will have pink eyelids. The eyes might not be pink, but the eyelids will be pink. And the eyes will probably be a lighter color than most dogs' eyes.
So if you ever meet any white dogs, now you know how to tell if they are albinos or not. Personally, I think it's better to be a black-and-white dog than a pink-and-white dog, but of course that's just my own humble opinion!