I do not have an answer. It could be allergies. However it could be a sign of another condition, possible cushings? I would take your dog to the vet to run some tests. Best of luck.
Welcome to the forum...I personally do not have a good answer....
Also, here on the forum...is a forum w/ a vet, Dr. Cheng...real good response and answers...
Have you inquired w/your personal vet??
Maybe someone else will post additional information...good luck to you and your friend!