Has your dog ever growled, or has a dog growled at you? It's not a nice experience, and unmistakable in intent. 'Stop doing that'; 'Go away!' and I'm sure, canine curse words would be included.
A low, rumbling grumble means that the animal is experiencing threat and also, warning you. Humans do it too... remember when your parent or teacher used 'that' voice, usually including your full name?
What happens next, if your dog does this to you?
Most people react with surprise, and then anger. We might tell the dog off, thinking 'how dare they!' It's a natural reaction. Instead, should we thank the dog?
I work with dogs that bite. They may bite people, other dogs, cats, squirrels, sheep. Dogs are equipped with straightforward instincts to survive. They need to eat, sleep, mate, protect themselves and their babies and friends. It is normal for them to become upset when any of these things are challenged.
Best of all, our pet dogs rarely bite unless that threat has become overwhelming. How do they let us know that they are unhappy? They look away in politeness, they may walk away, they may allow us to take things from them, and they trust us to be kind to them.
Sometimes that bond is not there, or the instinct to protect is strong. Your dog may have been taught by humans that something bad is about to happen. By the time the dog is growling, they are pretty stressed, and a bite is not far away.
In this case, be glad you hear a growl. This is your chance to change something. Don't punish your dog, since all this does is take the warning noise away. Your dog will still be just as upset (probably more so) and will probably just silently bite next time.
Instead, be pro-active. What caused the growl? Did you snatch something off the dog? Don't do that. Swap for a tasty piece of food instead. It's cheap and easy to get your own way without being mean. It will teach them to relax, as you have become a benevolent leader! They think they have something good, and you come up with something even better. Easy.
What worried the dog? A noise, a person, another dog? Your dog is probably nervous and needs your help (plus an experienced, registered professional) to learn not to feel fear.
Shouting or smacking your dog doesn't make you 'the boss'. Your job is to 'de-escalate', not fight, because the dog will always win if things become physical. Even if you succeed, your family and children may not in future!
You can still be in charge without being harsh. Learn to read your dog's body language. This way, hopefully you won't ever hear a growl.
And even if you do, be glad your dog is communicating with you in the safest way they know.