About a month and a half ago Bo took a dislike to a beautiful sedate Lab puppy she met. She didn't bite but was doing a 'squeaky' high barking, showing her teeth a little and snapping. Bo is a very social dog (a bit too social .. she loves all dogs big and small) and always rolls straight on her back when approaching a dog. We met the same dog in the vets when she went to have her spay stitches out and she did the same thing again! She has recently done this to 3 other dogs and we have come to see that they are all male puppies/male smallish dogs. Yesterday we went round PAH and a male Lhaso (sp) puppy slipped it's lead and ran up to her and she growled .. I was so shocked. 2 minutes later she was rolling around with a tiny Cav bitch. Today we have been round a steam fair (on lead) and she has snapped at 3 dogs that have approached her and when I asked they were all male. The final owner was great and took the time to let Bo and his pup (Irish Wolfhound - ish) meet properly. On the way home we went to our usual walk spot and she has run and romped with everything in sight. I am not sure how to address this problem and I don't want to make it worse but it needs sorting now!