When there’s someone in your life that you consider your “best friend,” you’d like to think that you know all there is to know about this special person. From their favorite music to where they grew up, it’s hard to be a good pal without a solid amount of knowledge about them.

With that in mind, dogs are often considered “man’s best friend,” and as such, we like to think that we understand them perfectly. They’re just dogs, after all, so they can’t have any deep, dark secrets — right?

Wrong! There are several facts about our furry friends that most people don’t know about, even if they’ve had them for years. Here are some of the most fascinating things that you may not know about your dog!

1. Dalmatians may be famous for their spots, but the puppies are not actually born that way. Their signature black patches of fur don’t develop until they’re roughly two-to-three weeks old.