I got my male german shepherd puppy from a rescue at 4 months old. He
is now 8 months old. He has been an exceptional puppy, but he has
lately been acting more aggressive toward my 13 year old cat. She
does have claws, but has not tried to hurt him. She has made it clear
to him that she doesn't want to play, but they don't really fight at
all. She simply tolerates him. This morning, as my cat was slowly
walking past him, he remained calm, and just watched her as she passed
within inches of him. Once her back was turned to him, and she was
preparing to come visit me, (could it be jealousy?) my GSD lunged at
her in a very aggressive manner. He did not seem to want to harm her,
but I'm beginning to get concerned that he may be developing a bad
habit so extreme that I may have to give him up.

He has been perfect up till now. This is the only real negative
behavior I have seen. He behaves as one would expect a puppy to
behave, but I can not allow him to terrorize my cat. She has lived
here for over 11 years, and this is her house.

To be clear on the dynamics of my house as some of this may be
relevant to how to solve this problem: I am a 33 year old female. I
am a teacher, so I am home a great deal. He has had an 8 week
training course at PetSmart and he graduated at the top of his class.
He is very smart. My fiancee (whose account this is) is here every
weekend, but otherwise it is just me and the cat here. He (the dog,
not my fiancee) sleeps in the house, on his own bed and receives a
great deal of attention/affection.

Does anyone have any recommendations as to how I can resolve this? I
love my puppy and don't want to have to get rid of him. Thank you
very much.
Debra