Is this resource guarding or playing?
Today my 1.5 year old pup Rascal displayed some concerning behavior. He was playing with a dog he's played with really well in the past and all of a sudden started growling, snapping, and barking when the other dog tried to take his stick. I quickly took the stick away. He then found a ball and then started doing the same thing with the ball, so I took the ball away and gave it to the other dog. The other dog's owner said her dog likes to do the same thing with balls, and sure enough she started guarding it and barking when Rascal got near. During this time they both would wag their tails at times, and it seems like when they both were "guarding" they were waiting for the other dog to try to come near and try to get the ball so they can protect it. It was as if they were playing a game, so I wasn't sure if he was actually being aggressive or if this was just another form of play for them. When they play they typically wrestle and fake bite each other but are not usually vocal. We will have Rascal evaluated for day care soon so I'm worried this type of behavior will keep him from passing his eval. He has never done this before and has had his balls/sticks taken plenty of time from other dogs. Other than a few growling episodes when he was 4 months old, we have not had any issues with him guarding with us and we can take any items including bully sticks, etc out of his mouth - although he will usually drop it himself when we approach.