Violence, fear, and physical injury are without question, the most difficult challenges you and your dog could ever face. This is very hard for us emotional creatures. We bring dogs into our lives because they share so many feelings with us. But when it goes wrong, it goes horribly wrong.

Aggression is the most important problem we manage in the practice of veterinary behavior medicine. Many people still love their aggressive dogs; others want to immediately eliminate that “vicious” animal from their lives. Huge mistakes can be made. In their attempts to make things better one person may inadvertently pander to a reactive canine personality. Another dog parent facing the same challenge may return the hostility. None of these reactive responses improves anybody’s life. Biting is the most serious of all behaviors. You cannot save a relationship gone-bad alone. If you ask us for help, you will have our full attention.

The purpose of this article is to provide information and help you prevent a worsening of your dog’s problem. I will explain why different types of aggression occur and some Dos and Don’ts so you can avoid injury in the immediate term. I will also review methods of management for the various types of aggression. This is a hugely complex area of behavior medicine with at least thirteen different diagnoses. Every individual case is different. Simply reading the following will not solve your dog’s aggression problems. But armed with a basic understanding of the reasons for biting, you can start the process of leading your dog to a healthier life. Kindness will be the cornerstone.

Only one-on-one behavior management can make things truly better. Our goal is safety and reliability for you and your dog. Throughout the consultation process we will be clear about what works, what is safe, and what we can accomplish.

What is a Dog?
Our civilized society is founded on rules of safe conduct. We have no tolerance for anyone trying to hurt us and we’ll do whatever it takes to protect ourselves and those we love. It is not acceptable for a dog to be a danger to people.

But canine aggression is not a black and white subject. The belief, held by many people, that every biting dog should be destroyed is a gross oversimplification. It is not true that any dog should tolerate anything from anybody anytime. Aggression toward an intruder or attacker is considered an act of canine heroism. A mother dog protecting her young against predators is natural. Biting is a context-specific behavior.

Our relationships with our dogs are actually pretty complicated. Dogs are considered man’s and woman’s best friends because we have so much in common. When they get sick or injured they call out to their comrades for aid-just like we do. They have a hierarchy. They have deference for their leaders. They hunt in a group. They are loyal to their comrades and they are affectionate. No wonder we bond so strongly with our dogs. They’re just like us. Sort of.

Studies of pet parents (people like you and me) have shown that we have healthier, more satisfying lives. We are more relaxed and stable. We live longer. In fact, we connect so deeply with our dogs that 75% of us regard them as children-like little people in dog suits. That’s powerful stuff. It also creates misunderstandings because for all of the similarities, there are significant differences between humans and dogs.

Human-Canine Relationships
Most dogs live with their people in relative harmony. We think we’re communicating with them only when we speak to them. In reality they are watching us almost continually and picking up signals we don’t realize we’re sending.

Our dogs receive subtle communications from us during nearly every waking moment. We don’t realize it because most of it is body language we aren’t aware we are sending. Dogs filter this information through their canine brains and respond. These pets are happy because they think their person is giving them behavioral cues almost all the time.

Some dogs misinterpret human communication to everybody’s detriment. They read the signals but they get it wrong. If the human sends even stronger, misinterpreted signals the dog can react badly. This miscommunication sometimes leads to trouble. You are your dog’s leader and it is your responsibility to learn to speak his language.

This is challenging. Communication between dogs in a group is seldom verbal; nearly all of it consists of covert body language. A shift of the rump, a turn of the neck, a furrowed brow, or the way the tail hangs all have important meanings. If you lean over your dog, hug him, grab his snout, or make direct eye contact he may feel threatened and react. You and your dog may think you understand each other but you could both be wrong.

It Can be Hard for a Dog to Live with Humans
Before getting more specific I’d like you to understand the bizarre pressures we well-intentioned pet parents unknowingly foist on our dogs. While it’s true that they have evolved over their thousands of years to live with us, they are still largely instinct driven. I believe that most of them could survive if released into the wild. Not only is your dog likely to know how to stalk and kill prey, forage and scavenge, she could also ingratiate her way into a free-living canine social group. She could fit into the social structure, learn a job, and pull her weight. She could go several days without a meal if food were scarce. The Call of the Wild isn’t really fiction.

Now take those canine social skills and try to fit them into the confines of an apartment or house with a small yard. How does a dog communicate by urinating? How can she establish a relationship with another dog with the totally artificial barrier of a leash or wire fence? Where does her territory begin and end? Many of the abnormal behaviors we treat are anxiety-based, partly because we unknowingly relegate our dogs to a contrived existence.

None of the above is meant to excuse canine aggression. Dogs have no business hurting people or each other. We humans have a responsibility. We have invited our dogs to live in our human domiciles. We are obliged to set them up to succeed.

Our dogs love us and become part of our lives. That commitment is healthy for all of us. If you give up and take a behaviorally maladjusted dog to the shelter or have her put down you are sending part of yourself to that place right along with her. Instead we can extend kindness to another creature and learn to make life better. We need that connectedness. Nearly every aggressive dog can be managed. So let’s get started.

Start with Physical Health
The first priority is a thorough physical exam and a lab profile. Liver and kidney disorders as well as thyroid disease, diabetes, and joint pain are a few common problems that can influence brain function. There are many others. If your dog checks out physically normal we can focus on behavior. It would also be quite helpful if you shoot a few minutes of video of your dog interacting. Please be low key-don’t set him up to bite. Reviewing even subtle interactions between you and your dog will tell us a lot.

The 13 Separate Kinds of Aggression

There are about thirteen recognized diagnoses for aggressive behaviors in dogs. While there are specific definitions for each of these categories there is a lot of overlap. To complicate matters, many aggressive dogs have other, coexisting, behavior problems.

As you read the following descriptions you may recognize things about your dog that will help you put a name on the problem. My hope is that this will improve your powers of observation. The more you can report to us, the better our chances of helping your individual dog.

Dominance Aggression
Dogs are social creatures who believe that they have a legitimate place in the hierarchy of their group. Those with dominance aggression may believe that they have the right to push other dogs around. While this can be dangerous, they pets are often some of the more treatable biters.

Treatment involves avoidance of situations that can set these conflicts into motion. Behavior modifications like desensitization and counterconditioning (teaching a dog to respond without hostility) can also help. This can take a long time. If anxiety is a factor medications can be helpful.

We have other tools. Head halters can help remind a dog to look to his person for behavioral cues. Temporary banishment (time-out) can defuse potentially incendiary situations. You’ll need help to carry all this off safely, effectively, and with kindness.

Everybody with this type of challenge wants a quick fix. Avoid dominance gestures like leaning over the dog, clamping its muzzle closed, staring, alpha rolls, pinning a dog on the floor, verbal reprimands. Improvements with reactive-aggressive dogs come with healthy leadership, not by intimidation.

Fear-Related Aggression
Dogs with this problem lose control of themselves when they feel threatened. They are OK, on the other hand, if no one makes the mistake of triggering their fear.

Fear-related aggression can be difficult to recognize in your own dog. To many people it seems like vicious behavior. It can appear unpredictable because dogs like this growl or bite almost as a “default” behavior. Something triggers their fear and they automatically do what they have done hundreds of times in the past-they protect themselves. Some dogs can freak-out so badly that they pass urine or stool. Nobody is happy.

Children, especially toddlers, are particularly at risk with an easily frightened dog. A loving child will want to pet and hug dogs, sometimes chasing them. No one would see the logic in a big dog being afraid of a tiny child-and this is where we meet disaster. No dog with a history of biting should ever be mixed with children. Even dogs with a stellar history should be carefully supervised with kids. With children Murphy’s Law is in full force.

Treatment for fear aggressive dogs starts with avoiding exposure to potentially unhealthy arousal triggers. More than just preventing injury we want your dog to abandon the neural circuits in her brain that have carried and stored her reactive default behaviors. She cannot get better if she continues to rehearse her ramp-ups in arousal.

There are other techniques that can make a difference. Many frightened dogs can learn to replace their fear responses with a different activity like following a command from their person. Bear in mind that this is one behavior that necessitates supervision and long term commitment. We see improvement in many fear aggressive dogs, but it’s a lifelong challenge.

Preventing bites requires careful observation. This type of dog can move from apparent tranquility to aggression in a few seconds. Invite your dog to come to you and always leave her an escape route. Speak quietly and don’t glare.

Food Related Aggression
Dogs and humans are different about food. At least in cultures where people are well fed, they don’t mind eating with others. But all dogs seem to believe that a famine will strike-in about 20 minutes. Only the assertive, aggressive, or crafty eater will survive. Hence there are lots of overweight dogs.

All of this is actually normal canine behavior. But dogs who growl, especially those who bite when a human approaches their food, can be dangerous. Some food aggressive dogs snarl while eating even when a person is some distance away. Others will try to growl and eat at the same time. If a dog like this perceives a threat to his food he can be dangerouss. The same can occur with rawhides, bones, or treats.

Food aggression can be easily confused with possessive aggression. The difference is that dogs who growl and bite over perceived threats to their food are neurochemically different. They are seldom aggressive about anything else.

The simplest management is to always feed your dog in an isolated setting. Never give him treats or chew toys when he is with other pets because you may risk a hostile event. Children should not be allowed to carry food if they are around a dog with this problem.

You can try to teach a dog like this to relax near his food but it’s far more reliable to feed him alone. The belief that all dogs should allow their person to take away their food is badly misguided. This is risky. Nobody learns anything good from the experience.

Interdog Aggression
These are dogs who don’t play nice with their friends. Much of what goes on between them looks rude to us but may be quite normal for them. You can allow them interact in their own way, but they must not be allowed to hurt one another.

The dominance hierarchy is often a factor in interdog aggression. The aggressor may treat another dog harshly when there is no legitimate reason for it. Altercations can result from competition for perceived scarce resources like food, toys, or sleeping areas. Unneutered male dogs may compete for a female in heat.

Dogs with this problem may attack another dog when the victim has done nothing to threaten the aggressor. Usually interdog aggression occurs between males or between females. These problems often start around 18-24 months of age, when most dogs reach social maturity. If you’re observant you will notice that the violence may be preceded by staring, bumping, or mounting. The aggressor may block the other dog’s access to their person or the food bowl. Older, weaker dogs often get the short end of the stick.

Some of these dogs are receptive to treatment. Start by making sure that everybody is spayed or neutered. By eliminating the influence of sex hormones we can help you determine which dog should be highest ranking. It will be essential for you to reinforce a very big gap in this newly defined hierarchy so the dogs can become clear on who has the most stripes on his sleeve.

True security comes from everyone knowing his or her role in the show. We can teach you how to employ a head halter to help even the king (or queen) of the hill understand that they still work for the master of the universe (that’s you).

Last, never try to break up a dog fight with your hands. A water hose, broom handle, or a sheet of cardboard or plywood works well. A 6 foot long leash, dragged around by each potentially aggressive dog, will be the best and safest method of separating dogs who may be already getting agitated. Grab the “drag line” of either dog early in the suggestive phase of the argument and banish him to another room. Be careful. Even your own dog can bite you in an aggressive frenzy.

Maternal Aggression
This problem is actually an outgrowth of normal behavior. Every mother has a right to protect her babies but hormone fluctuations and stress can create real problems.

These ladies cross the line when they aggressively guard their puppies or toys from a long distance. If a dog or person tries to remove one of the infants, the maternally aggressive mother will snap. She might eat the toy. If stressed and threatened she may even eat her puppy. Dogs in false pregnancy, beset by abnormal hormone levels, are more likely to display this kind of aggression than those with real live puppies.

Mother dogs are best left alone while in this state. If you need to clean the bedding or handle the puppies, it’s best to call mamma and reward her for being calm. Take her on a leash walk so that someone else can manage the housekeeping.

Maternal aggression resolves when the puppies are weaned or when the false pregnancy ends on its own. Many maternally aggressive dogs repeat their behavior with the next litter or false pregnancy. The problem also tends to run in families. Considering the risks, these dogs may be better off getting spayed.

Pain-Related Aggression
Dogs with pain have reason to be grumpy. Some types of pain are intermittent; others are felt continuously. Either way biting can occur without warning. The pet parent may be unaware that their pet is in discomfort. Often, the person who is bitten is a child who played too roughly or tripped over an arthritic older dog. Dogs in this situation may end up trying to avoid the child or, worse, become fearfully aggressive.

Other dogs in the home can also provoke a bite. The resulting painful wounds can cause the injured dog to associate fear with the biter. Attempts to control this behavior will fail if the pain is not accurately diagnosed and treated.

If the cause of the pain cannot be corrected there are still some excellent ways to help. In addition to medications, acupuncture, physical therapy, glucosamine/chondroitin, and other supplements it is usually possible to improve the quality of life and the behavior of many of these dogs. Physical therapy and consistent moderate exercise are valuable. Weight control really matters.

Regardless of circumstances, biting is never appropriate. Behavior modification is especially important when a painful dog is also showing fear and avoidance. The appropriate use of a head halter can help a dog take instructions from his or her person, instead of resorting to violence. Children can learn to be empathic, gentle, and considerate. This type of aggression is worth the investment of time and energy. Most dogs like this do well with behavior consultations.

Play Aggression
Dogs who start by having a good time, and then turn nasty, can be scary. This problem begins with rough play that escalates to growling and possible biting. It can involve people and other pets.

It is essential to recognize the difference between normal play and aggression. Dogs who play in healthy ways often have a high pitched yap while the aggressive ones may snap and growl in a low-pitched drawn out way. Raised hair over the neck and shoulders can be another indicator. Be careful. The transition from fun to danger can happen fast. A dog like this may try to grab a person’s arms or clothing and even chase them and bite from behind.

There can be important reasons for play aggression. Puppies who were separated from their littermates too young may never have learned how to play appropriately. Some youngsters are subjected to overly rough play like face slapping that is really more like agitation. It can be frustrating to teach a dog like this to play appropriately because they have learned to associate the excitement of play with aggression.

Active play should only involve toys-never your hands. Make sure that it is the person who  controls the situation-not the dog. Abruptly stop the play session by ignoring and walking away at the earliest sign of rising tension. Keeping play low key and gentle is best. Rough and tumble recreation should be avoided for the life of any dog with a history play-related aggression.

Other techniques are important too. The concept of earned privileges works well for these dogs because they must demonstrate a relaxed demeanor to be allowed to play with their person. Teaching a dog to bring a toy on command can be fun and rewarding all by itself

Possessive Aggression
These dogs will not relinquish a coveted item without growling, snapping, or worse. If they are also attention-seeking they may steal items and offer them to their person later for play. This behavior is much easier to manage if it’s recognized early. Many puppies show the first sign of possessive aggression when they are under one year of age.

For safety never challenge a dog like this by chasing, grabbing, and forcing compliance. Tensions can escalate. Only carefully administered counterconditioning can help.

Treatment for possessive aggression should be carried out cautiously to avoid a struggle. Your dog will worsen if results are expected too soon. The first step is to teach deference, meaning that you control access to all resources. This alone takes time. Your dog must also learn to relax so he can learn some new skills. If anxiety becomes a factor, extra patience will be in order.

The final step is called counterconditioning. The dog is initially taught to relinquish objects that have no meaning to him. As he earns reinforcers for it, items of increasing importance are used. All the while we respect the dog’s dignity and avoid dangerous standoffs. Kindness and patience will be necessary in generous quantities.

Frustration with this problem is understandable but you absolutely must avoid reprimands and punishment. Confrontation would destroy the relationship you are trying to build with your otherwise good dog.

Predatory Aggression
This may be the most frightening form of aggression because these dogs instinctively target very young, wounded, or old helpless creatures. Predatory aggression may be directed toward joggers, bicyclists, skateboarders, or passing vehicles. It is fairly easy to recognize this behavior. A predatory dog will hunker down quietly, staring and waiting, as she stalks her prey.

The classic predatory dog is attracted to small critters that have intermittent random movements. Young or ill animals, human infants, and geriatric people can behave this way. When wild dogs hunt for food they generally inflict one deadly bite, then shake their prey. If your dog acts like this, you may have a very serious problem.

Not all dogs who chase and bite are predatory. Those with territorial aggression may also pursue joggers and bicycles, but the element of stealth is missing with these dogs. An accurate diagnosis is important.

There are essential precautions that absolutely must be followed to keep the weak and defenseless safe. A predatory dog should never be allowed near an infant. Since these dogs are not a risk to older children and adults, there are plenty of homes where they can be well-suited pets.

Because of the high emotion and risks associated with predatory aggression you should not rely on your own assessment. If you suspect your dog of having any type of aggression you should consult a veterinary behaviorist before making permanent decisions.

Protective Aggression
Most of us feel safer knowing our dog will look out for us in a crisis. But some dogs take it way too far. Protective aggressive dogs bark and snap at people or dogs when there is simply no threat at all. This is highly unsettling for other people; it can also be dangerous.

This behavior can be manifest in many ways. A person or dog approaching a car or the front door of a house is subjected to explosive snarling and attempts to bite. A mildly raised voice or a person hugging the dog’s person may elicit canine violence. Protective aggressive dogs make inappropriate decisions about when to protect. Instead of having the good judgment to stand between their person and a questionable character, dogs with this behavior problem growl, snap, and lunge.

These dogs can certainly be treated but they should never be considered 100% reliable no matter how much progress they make. It is the responsibility of the dog parent to leash or confine a protective-aggressive dog when there is any potential for an inappropriate confrontation.

Behavior modification starts with avoiding situations where the dog might make a bad call. If visitors are expected the dog should be put elsewhere in the home prior to their arrival. Improvements come gradually because the dog is first taught to look to his person for behavioral cues instead of reacting. We lay the foundation for this by teaching a dog to look to its leader for opportunities to earn resources.

Like most behavior modification for aggression, this process is slow. It may seem tedious causing some folks to try to rush ahead. Good coaching will help you move your dog along at a steady successful pace. Since an underlying anxiety is a core problem for some of these dogs, medications can be useful.

Territorial Aggression
If you’re like me you want your dog to bark when some nefarious character drops by unexpectedly. But territorially aggressive dogs don’t show good judgment. They are out of control with their barking and lunging. Instead they should be watching their person, listening, and follow orders.

This behavior is similar to protective aggression. While the territory for many dogs is clearly defined by the boundaries of the car, the home, or the yard, for others it’s not so simple. Some dogs who aggressively and unnecessarily attack “trespassers” move their boundaries with them wherever they go.

Territorial behavior is normal for most social creatures. A problem exists when a dog becomes dangerous over nonexistent threats or in places that aren’t really his to protect in the first place.

Like protective aggression this behavior is potentially dangerous. These dogs should be well confined or controlled until behavior modification has yielded reliable results. They will never be completely dependable but many of them can get much better.

We manage these dogs much as we do those who are protective aggressive. Head halters, deference training, gradual desensitization, and counterconditioning can be rewarding.

Redirected Aggression
Dogs are mighty intense when they are enraged and right in the middle of biting or attacking. Anyone, human or canine, who interrupts an actively aggressive dog can be unintentionally bitten. People or dogs who attempt to break up a fight or an attack may be at the receiving end of redirected aggression.

This problem is more than just being in the wrong place at the wrong time. People who put their hands in the middle of a dogfight are almost guaranteed to get hurt.

Redirected aggression occurs when an interrupted, frustrated, actively hostile dog feels that he absolutely must carry out his assault. If you stop him from biting one individual, he may immediately turn in your direction and react. Your mistake may be interfering either physically or verbally. Not all dogs who are actively biting will redirect their aggression. But beware. Dogs on the attack can be dangerous to you.

Management of redirected aggression starts with preventing the original event. Dogs who attack cats, people, or other dogs need behavior modification that is appropriate to that specific type of aggression. But until the behavior has improved a potentially reactive dog should be isolated from aggression triggers.

Avoid water pistols, hoses, or foghorns to interrupt a dog with a history of redirecting her aggression. Even your own dog could harm you.

Idiopathic Aggression
This is very different than other forms of canine aggression and can be easily misdiagnosed. The simple definition of the term idiopathic is a problem caused by unknown factors. This behavior disorder is, however, quite specific. The aggression is sudden and literally unpredictable. It’s as though someone threw a switch. These dogs are violent with no warning and for no apparent reason. Some of them actually twitch and foam at the mouth. It has been called rage. The age of onset of this type of aggressive behavior is usually 1-3 years of age.

Before labeling any aggressive dog as idiopathic it is essential for a veterinary behaviorist to carefully evaluate for every other possible cause. Many misdiagnosed dogs are actually fear-aggressive. Most can improve with proper treatment.

Dogs with true idiopathic aggression are heartbreakers. Since every neurologic test and other method of assessment comes up negative, these dogs are essentially untreatable. The good news is that true idiopathic aggression is rare.

Summary
It is essential to everyone’s safety that you never consider any dog with a biting history as cured. Even with the major improvements we have seen in so many cases, a previous biter can always bite again. No matter how much your dog loves you and wants to please you, he or she could repeat a serious mistake. Children, the sick, and elderly deserve our greatest protection.

I don’t mean to discourage you, only to keep you realistic. With our help you can become aware of the early warning signs. We can coach you on effective management. Successful treatment of canine aggression is some of the most rewarding work I do.

Whatever path you choose, make safety your first priority. Even if bite prevention is your only goal we welcome the chance to help you and your dog.