Answer by
worker9084 (50)
There are many causes for dog hair loss or alopecia. Some include hormone imbalance, excessive licking, allergen in the environment, autoimmune disorders, excessive pressure, congenital lack of hair, hypersensitivity to infection, pregnancy and nursing, decreased thyroid function, ringworn, post-clipping alopecia, vitamin A deficiency. There are many more causes than listed here.