Puppies are born with their faces covered in hair, except for their lips and nose. As they get older, some thinning of the facial hair may occur but not to the point where the puppy will go bald. Other signs to watch out for besides facial baldness are crusting or redness of the skin and rubbing or scratching of the face.
Puppies allergic to flea bites can scratch themselves bald, even on the face. According to Mar Vista Animal Clinic, another common parasite on puppy faces are mites of the Demodex genus, which cause demodectic mange. Puppies get these mites from the mother dog.
Ringworm, caused by a fungal infection, is common in puppies because they do not have a natural immunity to it. Although sometimes ringworm goes away by itself after a few months, any puppy with ringworm is highly contagious--even to people. The "Dog Owner's Home Veterinary Handbook" notes that ringworm often starts on the legs and under the tail but soon appears on the face.
Some breeds have genetic problems that can result in facial balding. "The Veterinarians' Guide to Your Dog's Symptoms" notes that beagles are prone to going bald all over, including the face. The "Dog Owner's Home Veterinary Handbook" states that many breeds with black hair can suffer from black hair follicle dysplasia, which means they lose their black hair. A similar problem also happens with puppies of bluish coloration such as Dobermans or whippets when they are 6 months old.
Puppies from several breeds--including all huskies, Dobermans and the Great Dane--are prone to zinc-responsive dermatosis, which usually begins on the face when the puppy is a few months old or older. There is often a white crusting in the face as well. This is caused by zinc deficiency and is usually treatable.
A deficiency in the pituitary gland making growth hormones can occur in puppies of any breed and result in loss of hair on the face and body. According to "Dog Owner's Home Veterinary Handbook," this problem appears in puppies when they reach 6 months old or whenever that particular puppy reaches puberty. For an unknown reason, it happens mostly to males.