unexpected aggressive behaviour

[Homerhomer]

that is very puzzling.
Our Homer became aggressive towards some .... minivans. It started couple of days ago when my wife walked him, did it with me once, and today again with my wife.
With me I was kinda ready for it and was paying attention to his body language, so the moment it happened I gave him a hard leash correction (basically had him with his front paws hanging for a sec or two on the pinch collar). Don't think he got a message since he did it again this evening when walking with my wife (again was corrected with the leash so hard that he yelped).
Don't know what triggers this, we leave in an apartment so it wasn't that a minivan or people with the minivan were "bothering him" while he was left alone in the yard. We know where he is and what he does all the time (when outside). He is used to all kinds of vehicles, we live in a big city just off major road with a high traffic, so it's not like he hasn't seen a car in his life. And it's not all cars and not even all minivans. just once or twice during the walk something triggers in his little brain and I don't have a clue what.
Before he would heel couple of minutes every day to get to the park, now heeling on the high traffic are has became a BIG part of his walk, and I correct basically every turn of his head and every indication that he may be interested in anything else other than heeling (frowned forehead etc) with a pull of the leash (prong on).
I wonder what the experts think of it, and I am open to all suggestions.
BTW for the once who don't know he is 2 years old, neutered, and generally well natured.
Also when he was younger he would be friends with every single dog, now he is much more selective when it comes who he wants to play with and we have to be much more carefull with him when it comes to doggy play. Is this normal for a maturing or an adult male rottie.
Thanks

[Homerhomer]

Just to add, knowing that my dog doesn't have a rock solid temperament and sometimes gets scared (thunders, loud noices etc) I would think that this would be fearfull reaction, yet to inexperienced person that I am, it seems like he is just going for the "kill" without a fear (no hair risen on the neck or back), just frowned forehead and trying to attack with barely any warnings.

[Judi W]

Originally posted by Homerhomer
it seems like he is just going for the "kill" without a fear (no hair risen on the neck or back), just frowned forehead and trying to attack with barely any warnings.

I'm sure he is quite confident that the minivan is not going to retaliate which would account for his feeling of security is issuing the threats. :D

[Homerhomer]

Originally posted by Judi W


I'm sure he is quite confident that the minivan is not going to retaliate which would account for his feeling of security is issuing the threats. :D

as oppose to an umbrella that someone once open in front of him and he was hiding behind my legs :D

On the more serious note I hope he gets the message that this isn't acceptable, and doesn't assume that this behaviour will be fine towards different objects.

[Judi W]

It will come with time as long as you continue to give him clear messages. Dogs that have less confidence in themselves "borrow" from their leaders and make followers. That is why it is so important for them especially that they belong to confident and sure people. He'll get there.

[Homerhomer]

Thanks Judy.