My black lab is about one and ahe is losing lots of hair why ?

I'd ask the vet what he thinks and maybe draw some blood. This could be an illness or a mineral deficiency. What do you feed her. Stess, cancer, parasites, etc... all can cause hair loss in dogs.

Agreed, there are many reasons for hair loss. Most common include: skin infections, mange, allergies, thyroid problems or weather changes (a lot of dogs can look motley during change of seasons).