sorry Highdefinite for reposting 2 of your things today, but this is a really sad (at first) then happy (the outcome) video of a boxer that passed out during training.
From thehighdefinite's summary:
Canyon Crest K9 Training Center owner, Ron Pace, saves the life of a boxer with CPR during a regular training session. During the session, the dog suddenly collapsed and stopped breathing. Ron immediately applied CPR. Within a few minutes, the dog regained consciousness. Once the dog was resuscitated, the owner took him to the vet.