Hair loss on a four month old pomeranian

by lee
(Santa Clarita, CA)

Our four month old pomeranian lost her hair at three months old - is this normal? We had a pom before but I do not remember him losing hair like this pup.

When we bought her she was a big round ball of fur, and now she looks like a short haird pup! she has a long coat however it is very thin.

Lee