Hi I have a 7 yr old jrt, he is a social dog and I take him to puppy parks. Trouble is in 2010 he got attacked by a staff and was severely wounded with wounds deep they couldn't stitch. Good news he made a full recovery. Bad news every time he sees a staffy's he becomes aggressive and tries to attack, so I have to either put him on the lead or leave puppy park every time a staff arrives. What can I do to resolve this issue.