Hi, today in the field I had a very scarey experience with my boxer dog Roxy. She was running around when suddenly she stopped and started swaying and sat herself down. I went over to her and she seemed a little upset. She then got up and started walking but it took her a little while to get back to her normal bouncing self. This had happened back in the summer but I put it down to the heat. Several people reassured me saying that she probably just over exerted herself but I am not so sure. She is 2 yrs old.

I would get her checked out at the vet.  Could be a slight heart murmur (nothing to be alarmed about).  I had the same with a dog a number of years back.  It was a heart murmur but she was ok so long as she didnt overdo things.  Lived to a grand old age too.

I don't want to worry you, but I know that boxers are prone to heart problems. Have you had her checked?

Thank you for your quick replies. I did wonder about a heart murmour. I will definetly get her checked out now though. Does anybody know what the worst is that can happen if she really over exerts herself again, could be worse than I experienced today or will she know her own capabilities.

Ask your vet that question.  Just try for now until you know what the problem is, to keep her quiet and not overdo things.  Easier said than done I know.  Best of Luck with her and do let us know of the outcome.