A Common Problem
One of the most common issues that crop up when rescue dogs enter a new home is dog aggression. This is a problem that is not only frustrating, but can be potentially very dangerous. The intent behind the aggression that a rescue dog might display can vary greatly. Some dogs will bite just to get other dogs out of their space because they do not want to co-exist. Other dogs have the intent to do serious harm, and will not stop at just a bite.
When dog owner’s see dog aggression in rescue dogs, a common assumption is that the dog was a victim of a previous traumatic experience. One of the most popular stories with rescue dogs is that a dog who is fearful or aggressive toward other dogs was a former bait dog. This is a story that has been very popularized in the media, but it doesn’t have much truth in these situations. Bait dogs very rarely survive being a bait dog, and if they do, they have extensive injuries.
One type of experience that can cause aggressive behavior toward other dogs is being attacked by a loose dog. This problem is all to common all around the country, and most people who walk their dog regularly have had some kind of experience with loose dogs running up to them. This situation can absolutely cause a dog to develop insecurities when they see a dog out in public.

Lack of socialization also explains many cases of dog aggression in rescue dogs. It is normal for a dog to react poorly to things that they have not been exposed to when they were in their crucial early socialization period. Dogs that end up in rescue may have missed this window for a variety of reasons. Hoarding and puppy mill situations typically mean that the dog has never left the same place it was born in. Other dogs may end up abandoned or neglected a young age, or they could simply have been with someone who did not commit the time to give the dog what it needed as a puppy.

Experience vs Genetics
However, there are plenty of dogs who have had less than optimal socialization who still do fine when they see a strange dog. The same can be said for dogs who are generally good natured and get charged by a loose dog. When these triggers cause significant aggression issues, it generally means that there is also a genetic component. Most working breeds have a genetic tendency towards same sex aggression toward other dogs. Terrier and livestock guardian breeds are often naturally inclined to have a zero tolerance policy for strange dogs all-together.
It is important to recognize which things are experience related, and which are due to genetics. We can never make a dog forget what has happened to it, but we can provide lots of good experiences and show the dog how to work out of their issues. Genetics are a different story. Dogs with genetic dog aggression can be managed, but they are who they are.
How Misunderstanding Dog Aggression in Rescue Dogs Can Hurt
Many rescue dogs end up in the wrong home or in bad situations because the reason behind their issues is misunderstood. Well-meaning people may take a dog who is genetically dog aggressive and try to socialize it by taking it to the dog park. This is not only dangerous for the other dogs in the park, but it is unfair to the dog. That dog does not want doggie playmates, and trying to have them make friends is against their nature.
The idea that a dog has had bad past experiences can also lead to trouble. Unfortunately, there are bad things that will happen to some dogs over the course of their life. This can lead you to want to shelter your dog and to make excuses for their behavior. This also does a disservice to your dog, and prevents them from moving forward. Instead, you should acknowledge your dog’s past while working with a professional to build a plan to get your dog through their issues.