Olivia can be a snot when a tennis ball is around... she snaps, and if the other dog backs off, all is well. If the other dog reacts back at her, there will be a scuffle. It is my dog that starts it 95% of the time though. Take away the tennis ball, no issues.

She's a brat for the first 12 hours with a new dog in the apartment. Sulks, growls when they come near... and then she wants to play non-stop, cuddles with the other dog on the couch, etc. In a neutral location, everything works much better.

She gets reprimanded for either. I don't care how much she loves the tennis ball, she is not allowed to snap over it. When she does, fetch is over, ball is mine, forget it girl. In the apartment, I kind of let her do her thing, but no snapping. The growling etc I let go because if I reprimand her she stresses and the situation gets worse.