Dog suddenly became aggressive to our other dog

[billyuk1989]

Hi! To start off with some background information, dog A is 6 yrs M, and dog B is 1 yrs M. There is also a third dog, dog C who is 2 yrs F (although she isn't as prevalent in this). Dog A and B have been pretty much best friends since we got dog B as a puppy. Recently, dog B has become very aggressive towards dog A for absolutely zero reason (ex. trying to bite his neck, growling, snarling.). Dog A does not provoke dog B (to our knowledge), and does not return any aggressive behaviour. At first, we thought this was because dog C was in heat, so we waited it out and ended up getting dog B neutered. We absolutely thought that was it, that dog B was only aggressive because of dog C. But, as of recently we have attempted to reunite dog A and B, and to no avail. The behaviour repeated itself. At this point, we are wondering what we should do from here. Is this treatable? Will we have to separate the dogs permanently?

 

[imagebeastmarkbeast]

@billyuk1989 Is dog A neutered

 

[jake83]

@billyuk1989 If your female dog isn’t spayed your neutered dogs are still going to respond to her. If dog A is unfixed that could be why. Regardless of reason, these dogs now need a behaviorist to reintroduce them safely. If that doesn’t work, they might not be cohabit-able.