Bad Manners

[FionaBeth]

I have had my 1.5 year old black lab for just over 6 months (adopted from the SPCA). I did not take him to the dog park at first, because I was not sure how he would behave with other dogs. After about 2 months, I decided to take him. He was doing great and playing well with other dogs. However, over the past couple of weeks, I have noticed some problem behaviours, and I was wondering if anyone has suggestions for how to correct them. His behaviours seem normal, however they are amplified to the point that they are causing problems. He absolutely loves chasing other dogs. However, the other dogs do not always feel the same way about him chasing them. He is also very fast and can easily catch up to most dogs. As soon as he catches them, he puts his mouth on them (never bites down). He also has this deep growl and bark that have started to become a more common occurence as of late. So basically he will chase the other dog, and when he catches them he will growl and bark at them. If the other dog does not respond to his attempts to play, he barks at them. I do not want to return to the dog park until I have found a way to deal with this problem, because he makes some of the other dogs and owners nervous. I know that he is just trying to play, but he is not doing it appropriately. Any suggestions would be greatly appreciated.