Spanky pretending to be innocent

We had a bit of a scare last night. My Dad was trimming grass with a weed-wacker in our backyard, and Spanky watched with her usual intense fascination. Suddenly, she lunged at the weed-wacker (no doubt believing it to be a strange creature). My Dad immediately turned the machine off, but Spanky had already injured herself. Her mouth dripped blood all over the place, but she didn't yelp at all and she appeared fine otherwise (she's a stoic). We were all worried about her, because for the rest of the night she only rested on the floor and seemed to have no energy. I gave her some puppy pain medication, and this morning she seems to be back to normal. Sometimes she's too brave for her own good.