Why do dogs growl?
“A high-pitched throaty growl usually means the dog just wants to be left alone. It doesn't normally indicate that an attack is imminent – it's a warning. A medium-pitched, growl resonating from the chest indicates the dog is prepared to do battle. If pushed, the dog may attack. A low-pitched, "belly growl" or growl-bark indicates that the dog is about to bite.” in other words, when a dogs growl is high pitched you should probably leave him/her alone. Meaning the dog wants you to leave him/her alone. Other wise the dogs growl will get deeper. A medium pitched growl means that the dog is ready to defend him/herself so if you strike then the dog strikes. A low pitched growl means that the dog is about to bite meaning RUN.
What I think about it
Interpreting Dog Growling
“Figuring out exactly why your dog is growling is the first step in preventing escalating aggression. A growling dog is warning you that he may bite. Since we don't have a dog-to-English dictionary, the following can help interpret what a growling dog is saying:
•Fear: Dogs growl when they are afraid. A good example of this can be seen with dogs who are afraid of strangers. When a stranger approaches, a fearful dog may growl. This is his way of saying, "Back off."
•Possession Aggression: Some dogs growl over their possessions - a bowl of food, a toy, a rawhide bone. When a dog growls when someone approaches him while he's eating or chewing a bone, it is his way of saying, "This is mine, and I'm not sharing!"
•Territoriality: Sometimes dogs growl when they feel the need to defend their territory - think of the mailman approaching the door. When the dog sees someone who he believes doesn't belong on the property, he wants to let them know that they're overstepping their boundaries. Dog growling in this instance means, "Hey, you don't belong here, and I'm willing to protect my people and property!"
•Pain: Dog growling may also occur due to the pain of an injury or illness. There is usually a combination of things going on here. First, there is the unexplained pain going on in their bodies. Very often this is followed by veterinarians poking and prodding. This means on top of the pain, dogs are experiencing a great deal of confusion. The dog may associate the people trying to help him with the pain and fear. Dog growling in this instance usually means, "I'm in pain and afraid, and you need to stop hurting me."”
There are even more reasons as to why dogs growl. When dogs are afraid, they growl just to tell the stranger to step off. Dogs also growl because they are trying to protect something that is theirs, don’t try and take a dogs toy!(ha-ha). Dogs will even growl because of pain. If you are hurting a dog and he/she growls that just means, “I’m afraid of you so please don’t hurt me”.