Why is my dog the fun police?
I recently decided to foster a dog. Him and my male aren't getting along, but that's actually not really relevant to my dog's problem. The female I'm taking care of was trying very, very hard to initiate play with the foster. Whenever the foster would respond and they would begin play, Chrono would intervene and break them up by either putting his body in between them and physically separating them, or barking in the face of one of them. He would also hover around them waiting to intervene, and mostly his presence alone prevented them from playing.
He does this at the dog park too, which isn't usually a problem because our dog parks are more like hiking trails so the dogs usually sniff and continue on and there actually isn't much playing. If a dog tries to play with him he tends to ignore them and it takes quite a bit of coercion before he'll play with them. If they try to play with my female he usually objects to it and immediately stops the play, or he hovers around waiting to intervene.
Sometimes he does this with other dogs that are playing with each other that he doesn't even know. Normal play he's okay with but if they are vocalizing like growling or barking, or if it's extremely physical and sort of resembles fighting, he'll make them stop playing with each other.
What kind of behavior is this?