What causes aggression between dogs at the park?
In my many years of dog training the most common requests are; “Can you train my dog to walk on a leash without pulling and to not be aggressive when we go to the dog park?” Believe it or not, both go hand in hand. Improper leash handling often leads to aggressive behavior in dogs.
There are several Types of aggression in dogs.
It can be hard to determine what type of aggression your dog may or may not have. As trainers we also need to consider both the physical and mental health conditions when questioning aggression behavior. I will usually ask if you have seen a veterinarian to rule out any hormonal imbalances or other medical possibilities that may be causing the aggression issues.
These are what I call root aggression types; dominant aggression, territorial aggression and fear aggression are the most common forms I have seen. These are often exhibited in the more specific aggression traits such as dog aggression, aggression towards children and cars, etc…
In my opinion the worst form of aggression I have dealt with in dogs besides a combination of two or more root aggression types, is fear aggression. It is the most dangerous type of aggression. Fear instills panic and nothing good comes from panic. Dog owners often get bit in the process of trying to calm a dog with this type of aggression.
Fear aggression issues are often a source of habit, much like anxiety and usually started with an event that instilled a deep fear in your pet. Timid dogs often end up being fear aggressive if the handler doesn’t know how to bring the dog to a more confident state of mind. This event creating a state of fear often starts with mistakes made by inexperienced handlers unknowingly.
Improper leash handling can lead to bad manners and aggression.
If you are walking your dog and he is in an upfront position with constant tension on his leash you are making him feel uptight, on guard and in charge. This is improper leash handling! Over time this can initiate an undesirable situation such as a dog fight, not to mention the issue of a potential monster in the making.
If he is upfront and with tension on the lead this puts the dog’s body in a dominant position. You are molding an aggressive frame of mind in doing this. When an aggressive dog approaches your dog in this position, he may immediately become defensive, possibly challenging your dog. 
Some aggressive dogs may even attempt to challenge you if they should read your body language and perceive any fear, lack of confidence or too much confidence in your body language.
Picture this in your mind. Is this you?
You are digging your heels into the ground leaning back, holding your dog’s leash on an extended arm. Your dog is in a full forward motion leaning his chest and ears are forward. All the while, digging his paws into the ground with his tail up and his ears forward.
Your dog’s body language is saying that he is in charge and ready to take on the world. Your body language is saying you are submissive and not in control. You are not the pack leader in this situation.
If this in any way resembles your relationship with your dog, I can help you. Look up my page on Facebook at https://www.facebook.com/ddangiek9services/.