Why is your dog losing lots of hair?

There are a number of possible causes. Probably the most common would be Demodex also called "puppy mange." It is caused by a mite that commonly lives on dogs without causing any problems. However, in puppies, with incompletely developed immune systems they can cause problems.

The pup usually presents with small bald patches around the eyes and mouth. Medicated creams can be used to treat localized reactions and the pup's own immune system usually kicks in to deal with the problem in the end.

If the problem spreads to other areas of the body or lasts more than a couple of weeks the problem may be a more serious form of mange.

There are, of course, many other possible causes, including Allergies, ringworm, and parasites among others. Demodex is just the most common. Only a veterinarian can diagnose what a specific puppy's problem is and prescribe the appropriate treatment.