This video choked me up!

A boxer dog collapses and is revived by a trainer.

Intense but moving.

Boxer revived

Holy wow that was intense I cried like a baby, all I could picture was my Boxer laying there.

I'm guessing it was a heart attack??
They have so many heart problems, it's actually recommended to get your boxer's heart tested at the age of 2.

Scary stuff. I'm glad it turned out alright in her case, I'm still shaking!

In listening to the conversation, I get the impression that the dog had been having problems, perhaps seizures, and they were checking it out with some exercise when this incident happened.