Swimming Training Question

[kandy]

Parker and Hazel both swim really well - but Parker seems to have a problem. When he is swimming, he will try to dunk Hazel if she is anywhere close to him. Most of the time, when we are asking them to fetch the water trainer, we only let one swim at a time. This last weekend, my son's SharPei (Lexi) was trying to swim and Parker jumped in the water and dunked her. The water wasn't very deep, but it was still above Lexi's head. When he let her up, she came up under his chest, so she was still underwater. None of the dogs swim unsupervised, so I was able to grab Lexi out from under Parker quickly. She was scared, but unharmed. I doubt if she'll ever try to swim again.

My question is - how do I get Parker over this? I thought at first that he wasn't confident in his own swimming skills and was actually trying to hold himself up by putting his paws on Hazel's back. He is a very strong swimmer, although not as graceful as he could be. After this weekend however, I am thinking that he has some other reason for dunking the other dogs. Hazel swims much faster than Parker, so he isn't normally close enough to her to dunk anymore, but I don't want him doing that to a person or any other dogs while in the water. Any ideas?