The 8 Flavors of Aggression in Dogs


More than 50 years ago, researcher K. E. (Kenneth Evan) Moyer laid out what he called seven types of aggression, which veterinary behaviorists say apply to dogs as well as people. Animal behaviorist Nicholas Dodman, BVMS, would add an eighth, described here as the last item on the list.

All types of aggression in dogs require strong, loving leadership so that the pet can feel safe in learning a new way to cope in the world. A diet not too high in protein can help, too, as research has suggested a high-protein diet can contribute to aggressive tendencies. Additionally, a head halter or body harness allows for firmer control of a dog without the lunging and tugs-of-war that a flat collar and lead can engender. Of course, sometimes a basket muzzle erases the possibility of dangerous interactions for dogs with aggressive tendencies who are not in a mental place where they can control themselves.

But each type of aggression is also unique enough that different strategies are needed depending on the nature of the problem. If behavioral strategies are not enough on their own, it’s worth considering medication that will keep a dog calmer and more in control of himself — and more able to attend to the behavior changes you’re trying to teach him. Medication does not replace behavior modification techniques. It’s adjunctive.

1. Instrumental aggression. This is aggressive behavior to keep at bay someone a dog believes is standing in his way. Sometimes it can take the form of owner-directed aggression, where a dog experiences inner conflict because he is anxious about who is running the show; he does not have confidence that his human guardian is truly in charge. In such cases, a dog has to “learn to earn,” as Dr. Dodman says. An owner has to teach the dog that nothing in life is free, that he must work for his food or for toys (“Sit,” “Stay,” Come,” and so forth).

It’s also important not to push such a dog’s buttons. For instance, if a dog with instrumental aggression growls when you touch certain toys, those toys should be put away in order not to unleash his aggressive instinct. He can then have them back if and when he comes to understand that you are the keeper of the toys. Similarly, if such a dog snaps if you pet him while he eats, don’t pet him during mealtime.

2. Fear-induced aggression. “Fear aggression is much more difficult to treat than the other types,” Dr. Dodman says. “You always have to be vigilant about it, even though you can improve it greatly.” What’s key about dealing with aggression arising out of fear is managing the circumstances that cause a dog to react out of fright. For instance, if a dog reacts aggressively when someone tries to pet him, you should not let other people come close. It’s okay to say, “He’s not comfortable with people. Please don’t pet him.” If he barks ferociously at other dogs (while taking two steps backward, one step forward), walk him in quiet areas where you’re less likely to come across other people taking their own dogs out for a stroll. Over time, you will gradually be able to acclimate him to situations that currently make him uncomfortable, as long as you do it in a very controlled manner.

For a dog afraid of people, you might arrange for a “surprise” visit from someone who is very gentle and has a gentle voice but whom you instruct ahead of time not to look at your dog when she comes to the door or try to make contact with him, perhaps giving her a delicious biscuit to drop at the dog’s feet while making no move to interact. Over time, a fearful dog will come to gradually understand by more social gestures from friendly visitors that people are not scary. But it won’t happen overnight, and your efforts will only backfire if you “flood” your pet with social encounters she’s not ready for. You’ll further sensitize her to those people or animals or situations she fears. Take it very slowly.

Note, too, that in particularly difficult cases, an SSRI might not be the only drug a fearful dog needs to help curb aggression. That’s because serotonin isn’t the only neurotransmitter at work here. A fearful dog’s level of the fight-or-flight neurotransmitter, noradrenalin, may be too high, and to lower brain levels of that chemical, a veterinary behaviorist might also prescribe Catepres (clonidine), which ratchets down anxiety by blocking its action. “The SSRI works in the background to help keep a dog less anxious,” Dr. Dodman says, “while the clonidine works in the very moment of fear.”

3. Territorial aggression. To some extent territoriality is natural for a dog, Dr. Dodman says, “but you can have too much of a good thing.” For a territorial dog who might be prone to snarling at or even biting people he considers interlopers, what’s key is keeping him out of harm’s way. Put a head halter or a harness on him when someone comes to the door so that you can control his movements when the person enters. It’s okay to hold onto your overly territorial dog with a lead as an umbilical cord the entire time a visitor is in your home, if necessary. If the person is going to stay quite a while, you may want to section your dog off in the kitchen or other room of the house. With a strong leadership program in which you act fairly toward your pet but also are firm that it’s your house, not his, and that you will decide who’s allowed in, he will gradually get the picture that he doesn’t have to be concerned about who comes and goes because you’re handling it. But until you’re super-confident that he can keep from scaring people off the property, make sure he is secured and/or has a basket muzzle on when strangers come over.

4. Maternal aggression. Like territorial aggression, a little maternal aggression is good. Every species, the dog included, needs mothers who will act fiercely when necessary to protect their young. What causes a surge in protective aggression is a new mother’s surge in the hormone prolactin (which also causes milk letdown).

One solution for a dog who becomes overly aggressive when she gives birth, perhaps by not letting the human family pick up the baby pups or even go near them, is to eschew further breeding. With dogs, the idea is not to “win” by asserting your will or pushing your weight around. It’s to make everyone able to live peaceably together.

Some dogs with maternal aggression also respond well to a small dose of progesterone. That’s the pregnancy hormone that produces a calm, warm feeling in expectant mothers (human mothers included), and a little bit of it could work to counter the effects of prolactin.

5. Sexual aggression. This could include “a whole bunch” of different behaviors, Dr. Dodman says, “but maybe the best example is inter-male aggression” between two intact dogs. “They both come along surging with male hormones,” the doctor comments, “and each wants to be king. They gesture, and sometimes one might back off, but two uncastrated dogs are more likely to fight than any two others.”

The easiest way to control the behavior of a male dog who wants to “put up his dukes” every time he sees another unneutered dog is to castrate him. If that is not an option, keeping an aggressive intact male dog away from others who are also intact is the best bet, along with using control mechanisms like head halters and basket muzzles when it’s just not clear whether another intact male will amble along. It’s a type of aggression that’s hard to tamp down on through learned behavioral strategies.

6. Predatory aggression. A lot of people don’t really consider predatory aggression a true variation of aggression per se, Dr. Dodman says, because it’s not about a dog getting all bent out of shape. “There are no diluted pupils; he doesn’t raise his hackles.” It’s simply about chasing prey. “A dog going after a rabbit is not angry at the rabbit,” he points out. He’s simply following through on an instinct, not overreacting because of an imbalance in brain chemicals.

7. Irritable aggression. This is aggression that’s engendered by pain. An injured dog may be more likely to bite, or an itchy dog will become much more feisty because of the discomfort. The solution here is to treat the physical ailment; the aggression will then recede.

8. Pathological aggression. This is a type of aggression that Dr. Dodman adds to the seven originally identified by researcher K.E. Moyer more than half a century ago. It’s not about pain, but it is caused by illness — “possibly a borderline low thyroid state, certain brain tumors, or viral infections such as rabies,” he comments. Such medical conditions can cause aggression having nothing to do with bodily discomfort but need to be treated for the aggression to go away.


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