Dog aggression is normal canine behavior. In the wild, dogs use aggressive behavior to hunt for food, to defend themselves, and to guard their territory. Dogs use aggression to intimidate or harm, but most of the time, dogs threaten aggression without needing to follow through. The reason is that dogs who are properly socialized understand and respect the pack hierarchy.
Dealing with dog aggression
Because people don’t communicate in the same ways that dogs do, misunderstandings between people and dogs can occur. If a dog feels intimidated, confused or threatened by a person, the dog may growl, show his teeth, or snap.
Unneutered dogs can be more likely to display aggressive behaviors. If your dog has not been spayed or neutered, that surgery alone may lessen aggressive behavior. Besides spay/neuter, the best way to prevent aggression is to thoroughly socialize your dog as a young puppy. Introduce her to many different people and situations. She needs to experience positive interactions with other dogs and other animals, and the sights and sounds of everyday life. Take her out with you often and make new experiences fun. Make sure she understands that strangers can be her friend; she should enjoy being petted and handled.
If you watch dogs play together, they often mouth each other in a sort of mock bite. Other puppies and mom dogs teach soft biting during normal dog play. Many dogs play with people in the same way — by mouthing our hands or other body parts. Though mouthing is not biting, it can become too aggressive to be acceptable. To discourage mouthing, always use a toy to play with your dog. If you inadvertently become the toy, say “Ouch!” in a loud, surprised tone and take your hand away.
Dog aggressive towards humans
Aggression between dogs and people can be very dangerous. If your dog has ever hurt (broken the skin) of a person, it is your responsibility to seek help from a behavior specialist for your dog’s aggression. For more info about finding a behavior specialist, read "Aggressive Dog: Resources for Getting Help." You should protect both your dog and future victims by using a muzzle in situations like trips to the veterinarian or the groomer. If you are planning to use a muzzle, buy a basket-style muzzle and secure it with string in at least two places on your dog’s collar. Test the muzzle for safety and proper fit before trying it in any situation where it is truly needed. For more about muzzles, read "Muzzles: A Tool to Keep Everyone Safe."
If your dog has broken the skin on another dog, you should still be concerned about injury to people, since they can be bitten trying to stop dog fights. Again, you should seek help from a behavior specialist for your dog’s aggression.
Consulting a veterinarian
If your dog suddenly starts exhibiting aggressive behavior, there could be a medical cause, so consult your veterinarian first. If that’s ruled out, ask your veterinarian to recommend a behavior specialist. Choose an expert who uses reward-based training. Physical punishment won’t help the situation; in fact, it can make the problem much worse. You might also want to choose a behaviorist who does in-home evaluations. Aggression can be a very complex situation to resolve, so it can be potentially dangerous to follow recommendations made without doing an in-home evaluation.
Types of aggression in dogs
There are various types of aggression exhibited by dogs:
Dominance aggression is motivated by a perceived challenge to the dog’s social status or a challenge to his control of a social interaction. Most well-socialized dogs will work out dog/dog disagreements without a fight. Dominance toward people most often occurs when there is an unclear hierarchy. Some dogs may place themselves higher than people in their perceived pack, which can be a human family. Dogs who show dominance toward people need training to help reinforce the hierarchy. The training must be done with reward-based methods, not punishment.
Fear-motivated aggression is a defensive reaction that occurs when the dog believes she is in danger. For example, if she believes you are going to hurt her when you lift up your arm to throw a ball for a game of fetch, she may bite you. A dog may perceive the approach of another dog as a threat and act aggressively out of fear. Fear-motivated aggression can often be greatly reduced through training and socialization.
Prey aggression, or the prey drive, is motivated by a natural instinct to obtain food. If you find that your dog wants to hurt small animals (cats, rabbits, hamsters or small dogs), you must protect your dog from his tendencies. As the guardian of our pets, we are responsible for their behavior.
Territorial aggression happens when a dog defends what he sees as his property. The boundaries of what he considers his territory, however, may extend far beyond your yard.
Protective aggression is usually directed toward perceived threats to the dog’s family.
Possessive aggression happens when a dog is defending his possessions. Guarding objects like food or chew toys is quite common, but dogs will guard almost anything that is important to them — from a favorite spot on the couch to a dirty sock on the floor. You can help alleviate this type of aggression by working with trades. If your dog is guarding something, you can trade him for something better. For more details, read "Food Aggression in Dogs: Management."
Redirected aggression is relatively common and often misunderstood. If a dog is in an agitated, aggressive state, she may redirect her aggression onto someone else. For example, if two dogs are watching another dog (a potential intruder) walk by outside their fence, they may get so excited that they redirect their aggression onto each other.
Remember: Working with aggressive dogs can be dangerous, so use caution and seek help from a behavior specialist.