A growl is a valuable means of communication for a dog - something to be appreciated and respected. Never punish your dog for growling. You need to know when he's uncomfortable so he's not pushed past his ability to cope. Punishment can suppress the growl, eliminating the warning that he's about to snap or worse. Also, punishing a growling, upset dog can escalate him into full-on aggression.
If your dog growls:
Stop whatever you are doing. Wait until he relaxes, then move away so you're rewarding the relaxed behavior rather than the growl.
- Analyze the situation. What made him growl? Were you near his food or toys? Touching, grooming, restraining, making direct eye contact, taking something away or making him do something may also have triggered the growl.
- Figure out a different way to accomplish your goal. Lure with treats instead of pushing or pulling him. If you don't have to do whatever it was that elicited the growl, don't do it.
- Evaluate your dog's stressors and reduce or eliminate as many as possible. Stress causes aggression. Things like strangers, loud noises, thunderstorms, vacuum cleaners, harsh verbal or physical punishment and even your own stress can be upsetting to your dog.
Don't forget, play-growling is perfectly acceptable. As long as you're sure he's playing, there's no need to modify this behavior.