Hello! I own two pooches a Dutch ShepherdxSiberian Husky mix named Pyrrha and a Shar-pei-Shepherd-Pit weird cross of some sort named Kumatora.
Kuma is about to turn two on April 17th and I have had her since she was 8 months old, we would take her to the dog park alot and even though she had gotten into some fights she was generally friendly with most pooches and had never started ones, she recovered very quickly and was friends with the dog the next day. As of recently though she is rather intolerant of certain dogs. I recognized early on she doesn't do well with hyper-active (not high energy, they are fine) dogs or nervous dogs that wanna be super submissive around her, they tend to annoy her and don't listen well when she is telling them to back off, she absolutely hates dogs that leap up on me and voices herself well but again she will proceed to tackle the dog if it doesn't listen to me or her. She also doesn't like Retrievers, Poodles, or the combination of the two. LOL She has never started a fight out of being annoyed but she will FINISH fights if it protects the dog that is her friend, or if she picks out the dog that is causing the skirmish she will place them in a bite hold or tackles them. She never tries to puncture but she holds the dog in place. I grab her by the collar since it has a handle and ask the person to hold their dog still and get calm, in a few seconds she releases and then walks off. The more the dog moves the longer she'll hold until the dog is still.
Again this is not with every dog, she met some slightly nervous and fiesty bichon mixes and she played very happily with them, both male. She still plays nice with her variety of dogs friends and they range from shepherds, bully mixes, dogs im not even able to tell what they are. Giant great danes are great and because of her confident personality she overwhelms some of them. She's met little dogs and sniffed them and ignored them. Primitive dogs like huskies she does amazing with. She does get frustrated on leash but i've had her on a 50 ft lead and she still played nice.
This is just the general summary I will post a more in depth one in the proper spot in a little while to describe kuma's behavior in detail. I thought it was a fear thing but she's never reacting really for herself, she has a strong protective instinct that comes out full blown when its her sister in danger. And uses alot of body language to vocalize that her sister is scared but we've always had issues that dogs are not reading it well.