Aggression can be a normal behavior in dogs and cats. Cats and dogs in pain, frightened, stressed, or under duress often show signs of aggression. However, aggression that occurs with some regularity toward known or unfamiliar people or dogs/cats may be abnormal and problematic for both the patient and people. Aggressive dogs and cats are dangerous to themselves and others, yet many have a treatable behavioral pathology. Early intervention is always best because it will always involve the simplest treatment.

Often, aggression is a sign of anxiety and distress that is best addressed by either your veterinarian or a specialist in veterinary behavioral medicine working with you as the pet owner. Remember, the owners of aggressive pets are ethically and legally liable for their pets’ aggression. Clients should ask their veterinarians for an assessment and help at the first signs of any concerning or aggressive behavior. Treatment usually involves some environmental changes, behavioral interventions and treatment, and medication that will decrease anxiety and help the patient to acquire new behaviors more easily.


There are several recognized classes of aggression in dogs:•Impulse control aggression (sometimes called conflict aggression)involves aggression to people by dogs when the dog perceives that humans attempt to control the dog’s behavior or access to the behavior. These dogs dislike manipulation (for example, including being pushed from furniture, disturbed while sleeping, etc.). These dogs are anxious and attempt to control all interactions as a way of controlling their anxiety.

  • Territorial aggression involves dogs that forbid access to an area they feel they must protect. Most dogs will exhibit some protective responses to houses, properties, et cetera. Dogs with territorial aggression forbid access regardless of the context and the behavior of the person approaching. Furthermore, the response of the individual approaching may not matter if they are near the boundary—the affected dog reacts profoundly, regardless.
  • Anxious dogs become aggressive if they perceive risk. Fearful dogs choose to withdraw and not participate in social situations. If they can’t get far enough away from someone worrisome to them, these dogs will exhibit some or all of the behaviors associated with both fear and aggression: piloerection (hackles raised up), growling, snarling, staring, lunging, and biting, which usually occurs as someone moves. Dogs who bite when fearfully aggressive tend to do so from behind and may then withdraw after biting. For these dogs, biting is a last resort. If such dogs continue to be or feel threatened they will bite earlier in the sequence.
  • Food aggression describes dogs that react aggressively in the presence of food, when anticipating food, or when food is taken from them. This aggression could be directed at humans or at other animals. Some dogs will guard only what they perceive as valuable food items (e.g., real bones). The easiest and safest way to handle these dogs is to feed them undisturbed, behind a gate or door if needed, and only offer them special foods when they can be left to enjoy them unmolested.
  • True interdog aggression involves more than squabbling. This diagnosis can indicate a serious pathology when one dog will not tolerate the presence of another dog (or dogs, which is less common). It almost always involves dogs going through social maturity who are changing their social behaviors


  • The safety of humans and other animals is paramount. Accordingly, seek the help of your veterinarian immediately if your pet shows any signs of aggression. If your veterinarian feels that the behavioral problem is beyond the scope of his or her competence, referral to a specialist in veterinary behavioral medicine (in the US: or or a veterinarian with a special interest in behavior ( may be recommended.


Treatment requires expert help. The information here is general and is not adequate to deal with most aggressive pets. Seek help early!

  • There are many tools that can make it easier to manage the behavior of dogs and cats. All such tools must be used in a humane fashion – harnesses, head collars (dogs), and Sherpa bags are very helpful. Tools such as shock collars and prong collars are to be avoided. No device that relies on force, fear, or pain should ever be used (;;
  • Avoid situations likely to cause an aggressive reaction. Avoidance will keep everyone safe and will minimize practice of the pathologic behavior.
  • Simple training is not sufficient to treat pathological behaviors. Most certified, positive trainers now can recognize when behaviors will benefit from specialist intervention and are often willing to work with you and your veterinarian and/or specialist as part of the treatment. Behavioral and environmental modification will need to be geared to each unique animal, diagnosis, and settings.
  • Reward normal/good behavior but never punish the pathologic behavior. Veterinarians and specialists can help with this and may include in the treatment team a trainer who uses only positive methods and has special training to help with distressed dogs and cats. Not only does punishment increase the risk of aggression, but it tells the cat or dog only what you do not want them to do. To improve, cats and dogs need to know what behaviors will be rewarded and what behaviors will help them to feel calmer and happier.
  • Medication is a common component of treatment because all double-blind, placebo-controlled studies in companion animals have shown that patients taking medication acquire new behaviors taught through behavior modification more quickly. Premedication blood testing to assess medical risk is always recommended. Routine follow-up will involve repeated laboratory testing if treatment continues.
  • Remember that pain can cause aggression as a normal behavior. While most behavioral problems are not due to a medical problem, some are, which is why it is essential that you start by consulting your veterinarian. Furthermore, if your dog or cat becomes physically ill, this will often worsen a behavioral problem
  • The goals of treatment are to keep everyone safe, improve the patient’s quality of life and welfare, and ensure a happier household overall. Stressed and distressed cats and dogs do not have good mental health, and the preservation of mental health is at the core of behavioral medicine.
    AUTHOR: Karen L. Overall, MA, VMD, PhD, DACVB


From Cohn and Côté: Clinical Veterinary Advisor, 4th edition. Copyright © 2020 by Elsevier Inc. All rights reserved


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Chappelle Veterinary Clinic is a full service Veterinary Clinic which offers a wide range of veterinary care for cats and dogs, including routine exams, vaccinations, preventative care, diagnostics, surgery, spay and neuter, wellness services, dental cleaning, emergency and more.

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