Dog Aggression: Signs, Causes, and How to Manage

Dog aggression can be extremely distressing, and it’s also a common reason that people seek help from professional dog trainers. Often the way dogs communicate their level of discomfort or stress can be misconstrued as aggressive. It’s important to look at the root cause and do your best to manage your dog in those situations in the future.

Signs and causes of dog aggression

Common signs of dog aggression include growling, baring teeth, snapping, or even biting. Causes of aggression in dogs include medical conditions, a lack of proper socialization, fear, confusion, or guarding.  

For example, dogs in a shelter environment may be fearful or anxious due to their heightened stress level. Other dogs guard their food or other desired objects, such as toys. Pressuring dogs and/or not respecting their warning signs in these circumstances can lead to a bite. Fortunately, once a behavior source is identified and understood, it often can be overcome with time, training, and confidence-building activities. 

Keeping people and animals safe

Because it's so important to prevent injury to everyone while working with a dog who exhibits these behaviors, teach the dog to become comfortable with wearing a basket muzzle. This type of muzzle allows a dog to pant, drink water, and receive treats; at the same time, it prevents biting.  

A few changes in routine can ensure the safety of all the animals (and people) in your household. Use child safety gates, screen doors, or a crate to keep a dog separated from other members of the household if necessary. Consider separating the yard with fencing options or dog runs with visual blockers/barriers; do not chain or tie up dogs to keep them separated, as this can increase the level of frustration potentially leading to aggression. Make sure dogs get plenty of mental and physical stimulation to discharge excess energy that might otherwise manifest as frustration and aggression.

Veterinary checkup and spay/neuter

Any dog who has shown aggression should be examined by a veterinarian to rule out any medical problems. Pain, thyroid problems, illnesses, and hormonal imbalances can cause an otherwise friendly dog to be cranky or display aggression. Dogs with hearing or vision loss can also exhibit extreme changes in behavior. If a medical issue is discovered, the aggression might subside on its own once the condition is treated.

If your dog isn't spayed or neutered, we strongly recommend that you have it done immediately. Spay/neuter often can have a positive effect on behavioral issues. Check SpayUSA to see whether there's a clinic or veterinarian in your area that offers low-cost spay/neuter services. 

Teaching your dog (and yourself) basic cues

A dog who will respond to basic cues — such as "sit," "stay," and "come" — will be much easier to manage. You can help your dog master these simple cues with just a fundamental understanding of dog behavior and a little work. 

The following resources are a good place to start: 

• For the Love of a Dog: Understanding Emotion in You and Your Best Friend by Patricia McConnell
• The Complete Idiot's Guide to Positive Dog Training, 2nd Edition by Pamela S. Dennison
• When Pigs Fly! Training Success with Impossible Dogs by Jane Killion

Consulting a professional

It is highly advisable to have a professional trainer and/or behaviorist work with the dog. Professional trainers can provide valuable insight into dog behavior, and they can often pick up on very subtle clues and triggers that most of us are unable to discern.  

Even if you decide to rehome the dog, a proper evaluation from a professional trainer will help determine what type of environment the dog needs to be successful. Shelters and rescue groups receive many dogs who are simply deemed "aggressive,” so any additional information can help set a dog apart and increase chances of placement. 

The following resources can assist you in looking for someone in your area:

• Trainer Search from the Association of Professional Dog Trainers
• Find a certified trainer from the Certification Council for Professional Dog Trainers

Consider having a behaviorist assess the dog's history, temperament, and environment to help everyone involved understand what it will take to manage or correct the unwanted behavior. A behaviorist can also advise you about medications that might be helpful. 

To learn more about finding a certified behaviorist, talk to your vet or go to Certified Applied Animal Behaviorists or the American College of Veterinary Behaviorists (ACVB). Veterinarians who are board-certified in behavior have undergone extensive training and education in animal behavior. You can also find a consultant through the International Association of Animal Behavior Consultants (IAABC).

If you're not able to find a behaviorist in your area, some of the behaviorists listed with the ACVB and IAABC will do remote consultations with the pet caregiver and veterinarian. Don't be afraid to ask for options. 

Rehoming a dog with aggression issues

Rehoming might be the best option for a dog with aggression if there is something in their current environment they cannot be safely managed around — a new baby, for example. The dog can be in a new environment where they will be more likely to succeed and display positive behaviors. 

Make sure you understand what finding a new home for a pet entails. Potential adopters should be screened and be made fully aware of the behavior issues. It also can be helpful to write a great adoption bio for the dog that truthfully discusses their challenges but also why they would make a wonderful companion.  

If you are trying to place a specific breed of dog, you can find local listings of breed rescue groups by searching online. Here's a sample search combination: cocker spaniel + breed rescue + Montana. Remember, you are in control of where your pet is placed. Don't be afraid to ask for references and follow up on them.