I've got a border terrier about 6 years old whose well socialized with both dogs and humans, and for the first time ever, he got into a dog fight at the park we frequent. I'm worried he might he be developing dog aggression but dog fights happen so quicky its hard to tell who started it. It went as follows, me and my border terrier meet a man with 2 basenji's and as we meet, at the moment the dogs are directly next to each other(my border standing in between both basenjis), looking over their shoulders, something happened and it was too quick for me to see, but instantly my dog and one of the basenjis start fighting, it was odd there was no posturing or aggression before they got right next to each other, something happened and they just went at it. During the fight the other basenji started attacking my dog from the side too.

So my question is, is this common in the breed? The amount of times my dog has been in an actual fight is literally never, but the start of the fight was so fast I couldn't see who was at fault. As Basenji owners is this a known trait flaw in the breed? or is my dog now just getting grumpy with age? The basenji's seemed really well trained too, this was an off leash park and they were walking side by side not a foot in front of their owner.

Anyways hope someone can help me out with info on this. Thanks