Border Terrier Forum:
Licking inside other`s mouth

I have a 7 mo old neutered B.T. Our 4 yr old spayed Jack Russell Terrier has begun licking the teeth and all inside the mouth of the BT. She does this every day for 5-10 min or as long as the pup will tolerate it. Usually first thing in the morning, before hes had any food. She does not "groom" him in any other way. Ive never seen this before---whats this behavior about ?? Thanks