Jasper is a cocker/springer cross, and ball obsessed. When I take him out for an off lead run every morning I always bring a tennis ball. He ignores everyone and everything for the ball, so no running up to people or other dogs and his recall is excellent. This morning we met a couple of other dog walkers, and one had a 5 month old labradoodle. Jasper ignored everyone in favour of chasing his ball. The pup started chasing after him in that uncoordinated 'my feet are too big for me' way. Jasper got his ball, then turned to the pup and chased him off. There was some barking and jumping at the pup's face, but no contact. The pup's owner was upset, and I apologised profusely. He has never done this before. Should I remove the ball when we're around other dogs? Or can I train him to react less aggressively?