6 month old exhibiting aggression towards food/cats
This is my first time on this site - and it looks like there's a lot of great information on here - so I was wondering if you guys would have some advice with how to handle some recent aggression issues.
The first issue that has come up and recently gotten worse is that he is becoming very food aggressive. Not towards me (I can take away his food bowl, his kong, touch his face while eating, etc), but if another animal approaches his food bowl or one of his bones, he reacts. For his bones, he will lunge (not snapping, but assume a 'back off or else' posture) and then go back to his bone. For his food dish, he will raise his lips, growl and snap. Also, I took him over to the pet store today, and he found a shelf that had some kibbles underneath it, and while he was trying to eat them up, another dog came over to say hi and he began to growl and snap at him. He even made contact with the other dog (didn't break skin, but definitely grabbed a hold of him). I immediately pulled him off and re-directed his attention to another aisle, but I really would like to figure out a way to help him work through this.
In addition, my roommate has a cat, and whenever the cat goes over to eat from its food bowl (it's on a raised table), Chief (my puppy) will run over and stare at him and invade his space. I even noticed today (after we came home from the pet store) that he even lightly snapped in the direction of our cat to try to get him away from his food bowl because Chief thought that a kitty treat that had fallen out of his foodbowl was his. I definitely don't want him to ever hurt our cat or any other dog...so I was wondering if anyone had any advice to curbing this behavior or better managing it?
Also, it seems that Chief doesn't seem to quite understand to just leave the cat alone in general. Our cat isn't the most aggressive of beings, and hasn't really gotten a good swat in ever to tell Chief that enough is enough, so Chief really likes to loom over him and kind of bully him around. Does anyone have any advice on how I can teach Chief to just relax when our cat is around? Instead of constantly bullying him or trying to keep him away from his food bowl?
Lastly, (I swear Chief isn't a bad dog, it's just he has a lot of quirks that are coming out and I'd really love some advice on how to handle them!) Chief can also be a bit of a bully to very submissive dogs. If he can, he will grab them by the scruff and pin them (and just hold them there). He's made numerous dogs make the 'ow' noise, and this does not deter him from holding them down. He sometimes will even then precede to drag them around for a few feet if they're light enough. I've been working on telling him to leave it, removing him from the other dog, and then making him sit and calm down before returning to play - but is there a better way to fix this behavior?
Thank you so much for all your advice! This is my first german shepherd puppy and I just really want him to grow up to be the good little man I know he can be!