re: How to socialize a dog showing increasingly aggressive behavior?

The muzzle would solve your problem quickly regarding your dog being able to not do damage to other animals, but does nothing to solve your issue. The fact the dog will not listen to you telling it no or to leave the other animals alone, it sounds like it's an obedience issue. You can try a pinch collar, choke chain (you may have both of these already) or an e collar. E collar's, when used correctly, are powerful tools in changing a dog's behavior. Youtube has some good video's and sit means sit makes a great collar (about $250 to your door w/a lifetime warranty). Good luck !