Hi. I have a 7 year old lab and she is starting to lose a little bit of fur on her chest I'm not really sure why. She does not have fleas or mites, but she does have a gluten allergy but we get gluten free dog food. She has been licking the spot where she is losing the fur. If it gets any worse I'm going to take her to the vet but what do you think it is, should I go ahead and take her to the vet know. Here is a pic. Thanks