My dog was the runt of his litter. he has some teeth problems & he's never had much hair on his neck, chest, and belly. The vet said it was hereditary and that it could be fixed by giving him melatonin twice a day. This sounded weird but i haven't done much research. Wondering if anyone knows about chis w hairloss since puppyhood. Any information helps! Attached pictures bc he's handsome.