I just rescued 8 month old german shepherd/mastiff, Lola from the humane society. She is beyond sweet but a little nervous. My roommate rescued a 4 month old hound mix. Both are relatively well behaved individually but they both are starting training. My problem is when they are together. They play so rambunctiously and it keeps getting worse. Lola is very friends and would never hurt my roommates puppy (despite being triple her size) but she cannot control her excitement around her. My roommates puppy will start biting at Lola's face when she is playing and in Lola will bite her neck (not ever hard) if either of them yelp they back off. They used to be okay on walks together but i just tried to take Lola out and she nearly pulled me over trying to get to my roommates dog. I had to hold her harness and she literally threw herself forward and nearly hurt herself landing on the ground trying to get to my roommates puppy. We tried to continue walked but she wouldn't stop so we had to separate their walks. I just don't know what to do with her. I don't see it as aggression because if she wanted to hurt my roommates dog she easily could have. I think it may be anxiety causing this but I'm a bit at a loss for how to control her around my roommates dog. She is perfectly fine and polite with other dogs (albeit a bit excited) so I don't know what the trigger is.