Fear Aggression in Dogs

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by Dr. Nicholas Dodman

Dr NIcholas Dodman

One of the most common behavior problems I see is called fear aggression. In a nutshell, it is aggression directed at unfamiliar people or most other dogs. It stems from lack of socialization and/or adverse experiences and — to the dog — it makes perfect sense. If a dog feels threatened by a person or other dog, it makes sense to either: a) run away or b) do everything possible to cause them (and the whole situation) to go away. The fearful personality may be partly inherited but the greatest cause of fearfulness in dogs is impaired nurture during a formative period of a pups’ life or some particularly heinous experience. The sensitive period of learning in pups, including the socialization period, is generally cited as the first 3 months of a life, though a secondary period of fairly rapid learning seems to occur from 3 to 6 months of age — i.e. up until the end of the juvenile period. After that, a dog is what he is personality-wise – confident or anxious/fearful. Some dogs never develop sufficient confidence to become fear aggressive and simply shrink away when faced with perceived threats. These are the shrinking violets of canine-kind. Others develop a proactive approach for dealing with supposed enemies and start showing aggression to strangers in the 6 – 9 month window as a results of increasing maturity and confidence. So fear aggression seems to be a composite condition involving a combination of mistrust and/or fearfulness plus a certain willingness to do something about it.

Learning is also involved in the equation, as fearful dogs realize that their growls and other threats achieve the desired effect — so fear aggression unfolds like a poisonous flower from its first, early appearance to maximum intensity at the time of adult maturity, that is, 2 to 3 years of age. The most common human targets of this aggression are men – particularly uniformed visitors but also tall men, men with beards, men wearing hats, and anyone with an unusual appearance (persons with a limp, walker frame, and so on) — and children. The reason for this preferential mistrust is, I believe, that men tend to be more aggressive in their dealings with dogs and children often do silly and upsetting things that scare young dogs and make them wary around them.

Fearfulness and mistrust leading to fear aggression can never be totally eliminated because it is ingrained from early days, but the problem, if managed correctly, can reduced to livable proportions. It’s possible to desensitize a fearful dog to a particular person or persons but it’s impossible to desensitize a dog to everyone.

Fear aggression can present as a noisy and scary warning with the affected dog never actually biting or can be result in injury to people in more committed dogs lacking bite inhibition. Fear aggression is a common reason for dogs’ surrender to shelters and having that history is bad news in terms of future placement. It’s best not to allow the condition to develop into the full blown syndrome in the first place. If a dog shows any signs of fear aggression early, here are some things that can be done to improve the situation, sometimes with great success.

  1. Exercise – the great mood stabilizer. Fear aggressive dogs benefit from the maximum amount of off-leash aerobic (cardiovascular) exercise that owners can manage and the dog can handle. This might sound like a Catch-22 situation because off leash the dog may attack someone – or another dog. The fact is that many fear aggressive dogs are at the worse on leash (trainers sometimes call it “leash aggression”) and can be virtually non-aggressive off leash and away from their own territory. Certainly that is not always the case so great care must be taken. Dogs who are aggressive off-leash can be exercised in enclosed areas – like a large backyard – where the public is not around. Most healthy dogs need to run around for at least an hour a day, possibly two. The work-out they get will release mood-stabilizing neurochemicals and make them calmer and less aggressive. A tired dog is a happier dog – and often a much less aggressive one.

  2. Diet – Particularly for dogs whose fear aggression has a territorial component (worse at home or in the yard), a maintenance level of protein in the diet – around 18 – 20% protein “as fed” for dry food — as opposed to a higher protein content [26-30 percent or higher] –can help reduce aggression. Halo’s Vegan Garden Medley provides an example of a diet that fits the bill. See http://shop.halopets.com/Dry-Dog/Halo-Dry-Dog-Vegan-Garden-Medley-4Lb

  3. Clear Communication – Have everyone in the family use the same one or two-syllable commands – and ensuring that commands are said only once before stepping in to make the desired response reality. Useful commands are “Leave-it,” “Sit,” “Quiet,” “Come,” and “Wait.” The sequence should be as follows:

    (1) Give the command (once)
    (2) Make it happen
    (3) The desired response is achieved
    (4) Reward, in the form of petting, praise, or a food treat is then given immediately.

    The challenge for most people is item #2. How do you benignly make sure it happens? The answer is in the next section.

  4. Head Halter for Control. A head halter applies pressure around the muzzle (“maternal point” – gently holding a pup’s muzzle is their dog mom tells them to quit something they are doing) and high up on the neck (“leader point” – think of how a mom dog carries her pups). The result of applying gentle upward pressure on the leash attached to the head halter is to cause the dog to stop what it doing and relax. A head halter (with leash attached) can be used to shape a behavior you desire from your fearful dog when visitors arrive at your home or when you meet people or other dogs on the street. Here’s an example: Dog barks at stranger; owner says "Quiet” but the dog continues to bark. Sustained but gentle upward tension is applied to the leash until the dog become quiet. It is immediately praised and rewarded.

  5. Respect the dog’s needs. Fear aggressive dogs are, by definition, frightened of strangers or unfamiliar dogs. So owners should protect them from unwanted advances of well-meaning people or other dogs. Strangers should be told to totally ignore the dog; no looking at, no talking to, no touching, no reaching out an outstretched hand (“to be sniffed”). Owners of fear aggressive dogs should instruct owners of other dogs who are the target of their dog’s fearfulness and aggression to put their dog on leash and move away to a non-threatening distance. Also, feared people or other dogs should be discouraged/prevented from direct approach – rather they walk (or be walked) around the fearful dog in a circuitous path to avoid unnecessary confrontations.

  6. Counterconditioning. If thing are going well, strangers who are ignoring a fearful dog can sweeten the pot by tossing food treats toward the dog nonchalantly for the dog to gobble up. They don’t even have to look at the dog while doing this – and it’s best if they don’t. A dog that eats in front of someone is losing its fear and entering a different mode – an appetitive one. For non-food driven dogs, toys or tennis balls can be used in the same way.

  7. Medication. For refractory cases of fear aggression, non-sedating mood-stabilizing medications can play a role in recovery. I often refer to (what I call) “pharmacological desensitization.” Basically, if the dog can be made to feel more comfortable and less threatened in front of well-meaning people (who have food treats!) or properly controlled dogs by use of medication, they can learn that strangers are not as bad as he thought they were. The learning may then “stick” and as the medication is tapered off.

Putting 1 through 7 into practice simultaneously (or even 1 – 6) can produce huge improvements in fear aggressive behavior and save unfortunate accidents and dogs lives. It is a useful truism to remember that insecure dogs need strong leaders. Not mean ones, rather ones who say what they mean, mean what they say, and ensure that their instructions always result in their dog conforming to their wishes. To make that happen, I reiterate that a head halter, preferably a Gentle Leader head halter, is an excellent tool for controlling and retraining such fearful dogs.


Dr. Nicholas Dodman is a Professor in the Department of Clinical Sciences at Cummings School of Veterinary Medicine and Director of the school’s Animal Behavior Clinic. He is also Chief Scientific Officer for the CENTER FOR CANINE BEHAVIOR STUDIES (centerforcaninebehaviorstudies.org). He has written over 100 scientific articles and several popular press books, including The Dog Who Loved Too Much and The Cat Who Cried for Help.

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