Dog-dog aggression is a very serious matter. Until your dog’s successfully treated, keep him a safe distance from all other dogs (“safe distance” meaning the minimum amount of space he needs to remain calm and unstressed).
Even if physical contact is never made, managing a dog who’s pulling and lunging on-leash is very difficult–not to mention stressful for all parties–and attempting to defuse an attack in progress is downright dangerous.
Be aware that even the briefest fight can result in a fine, a lawsuit, or–most devastating–the injury or loss of your pet, or someone else’s. Whether on a walk, at the groomer’s, or just visiting the vet, watch for the major warning signs of aggression toward another dog:
Direct eye contact
Teeth exposed toward the other dog
If you see these behaviors, calmly remove your dog or redirect his attention to something else.
Nature and nurture each play a role in shaping your pup’s personality. True, certain types of dogs have been bred specifically to be aggressive, but with the right training and socialization, environmental factors can and often do triumph over genetics. Similarly, breeds known to be gentle and easygoing can become highly aggressive if mistreated.
If you’ve brought home a puppy, you’re in a good spot: his behavior is yours to shape. If you have an older dog and you suspect he may be dog-aggressive, training–or rather, retraining–will be much trickier. In such cases, consulting a professional is always the best path.
How to treat the problem
Most behaviorists use desensitization to treat dog-dog aggression. Using plenty of positive reinforcement, you’ll gradually decrease the physical distance between your dog and other dogs without raising his anxiety level. This takes a great deal of time and patience–often several months to a year–but ultimately your dog will associate the approach of other canines with good things (praise, treats, attention). Get guidance from a behaviorist before beginning desensitization.
In the meantime, don’t increase your dog’s stress by physically punishing or yelling at him, and forget prong or choke collars. Added pain and stress will only escalate your dog’s anxiety and increase the aggression. The last thing you want to teach him is that the presence of other dogs mean bad things happen.
How to prevent the problem
There’s no surefire way to prevent aggression, but there are basic steps you can take to greatly decrease the chances your dog will develop a problem:
Socialize your puppy. Arrange supervised play dates with other pups and encourage interaction with well-mannered adult dogs who can teach your puppy how to behave.
Neuter or spay your dog as early as possible–this will greatly reduce hormone-driven aggression.
Always treat your dog with kindness and respect, using positive reinforcement to train. Physical correction, intimidation, and isolation only encourage aggression by adding to a dog’s anxiety.