How to Handle Aggression Between Dogs (Inter-Dog Aggressive Behavior)


PetMD Editorial

. Reviewed by Lauren Jones, VMD
Updated Apr. 27, 2022

Interdog Aggression in Dogs

Inter-dog aggression, or aggressive behavior between dogs, occurs when a dog is overly aggressive toward dogs in the same household or unfamiliar dogs. This behavior is often considered normal, but some dogs can become excessively aggressive due to many factors.

Inter-dog aggression occurs much more frequently in non-neutered male dogs. Common signs usually start appearing when the dog reaches puberty (between six and nine months old) or becomes socially mature at 18 to 36 months. Generally, inter-dog aggression is more of a problem between dogs of the same gender.

Symptoms and Types of Aggression in Dogs

The most common symptoms of inter-dog aggression include growling, biting, lip lifting, snapping, and lunging toward another dog. These behaviors may be accompanied by fearful or submissive body postures and expressions such as crouching, tucking the tail under, licking the lips, and backing away.

Typically, before a severe inter-dog aggression incident in the same household occurs, more discreet signs of social control will become noticeable. One tactic a dog may use is staring and blocking the other dog’s entrance into a room. A specific condition sometimes triggers the aggression, even though the dogs normally get along well.

Causes of Aggression in Dogs

The causes of this condition vary. A dog may have become overly aggressive because of its past experiences, including abuse and neglect. For example, it may not have socialized with other dogs as a puppy, or it may have had a traumatic encounter with another dog. Dogs rescued from dog fighting operations also tend to exhibit inter-dog aggression more frequently. 

An owner's behavior may also influence a manifestation of the condition (e.g., if an owner shows compassion for a weaker dog by punishing the more dominant dog). Other reasons for aggression are fear, wanting to protect territory and social status, or a painful medical condition. 

Diagnosing Aggression in Dogs

There is no official procedure to diagnose inter-dog aggression. Some symptoms are very similar to canine “play” behavior and excited, non-aggressive arousal. Biochemistry, urine analysis, and other laboratory tests usually yield unremarkable results. But if any abnormalities are identified, they may help the veterinarian find an underlying cause for the aggression. 

If a neurological condition is suspected, advanced imaging, like CT or MRI scans, may be necessary to determine whether it is a central nervous system (CNS) disease, or to rule out other underlying neurological conditions.

How to Handle Dog Aggression

There is no real cure for inter-dog aggression. Instead, treatment is heavily focused on controlling the problem. Owners must learn how to avoid situations that encourage aggressive behavior in the dog, and to break up fights quickly and safely when they occur. In situations where aggressive behavior is more likely to occur (e.g., walks in the park), the dog must be kept away from potential victims and be under constant control. The owner may also want to train the dog to feel comfortable wearing a protective head halter and basket muzzle.

Training for Aggressive Dogs

Behavioral modification plays a crucial role in the treatment of aggression in dogs. Utilizing licensed, professional veterinary trainers is absolutely necessary. The aggressive dog is slowly conditioned to not fear or react to other dogs through a variety of positive reinforcement training techniques.

Unfortunately, some owners cannot control, train, or avoid situations of dog aggression. In these cases, options include re-homing the dog to a situation that better fits their personality. Some dogs may be deemed unsafe to be around other animals, as well as humans. In these cases, humane euthanasia may be the best way to assure everyone's safety and well-being.

There is no specific licensed medication used to treat inter-dog aggression. However, there are many behavioral medications that can help treat anxiety or hyperexcitability, such as Prozac, Xanax, trazodone, acepromazine, and gabapentin. Some of these drugs are used on a daily basis, while others are only used for situational events.

Successful treatment of inter-dog aggression is usually measured by the decrease in severity or frequency of incidents. In addition, the treatment recommendations need to be implemented over the entire life of the dog. Even if aggressive incidents are completely eliminated for a period of time, relapses may occur if the owner does not strictly adhere to the recommendations at all times. Owners with aggressive dogs need to work closely with veterinary behaviorists and veterinarians to meet treatment goals. It takes a lot of time and patience, but many dogs are capable of controlling inter-dog aggression and leading normal, happy lives.


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