Change in fur color

Question
I have 2 rottwieler/German shepherd/black lab mixed dogs. They are both 5 years old now. They both have black coats of fur. They both have smooth and shiny fur, like a healthy coat should be. However, the female's coat looks as if it is beginning to gray and the tips of her fur is turning white. It is all along her back as well as her face. This is weird to me because I've never heard of a dog developing gray hair. Can you please tell me if this is normal or if I should take her to a vet?

Answer
Dogs will sometimes turn gray as they age, most especially around the muzzle, but it can happen all over.  Five years isn't necessarily old, but since she is a large breed you could definitely consider her middle aged.  Since she has dark colored hair anyway it is going to be that much more noticeable.  If her skin appears normal and healthy, and she is acting as usual, then I don't think you have anything to worry about.

Amanda