Have your vet check for mange - i have heard of 3 or 4 young dogs lately that all of a sudden when they are stressed ( such as coming in heat ) they
develope sarcoptic mange ( it is carried by most dogs and gotten from their mothers but not evident unless their immune system is off balance ) I would definitely rule that out and there is another food on the market that is superb for coat / skin problems or i should say to eliminate the problems - it is called Lifes Abundance and you can see and compare it by going to
www.healthypetnet.com/nolensyorkies