Unfortunately didn't see exactly what happened. She jumped off the deck (per usual) and the squirrel must have been in the flower bed. She pulled a 180 to come back towards the deck after it, busted through the plastic fencing I'd stapled up to keep the dogs out from under the deck, and proceeded to chase it while under there. Heard a collision and a yelp and she came out with a small abrasion (pencil eraser sized) on her head. I didn't realize it was more than that until I had her in the tub to get the mud off. A tiny superficial wound, a dent, you could see the displaced bone, and a bloody nose. We're guessing she smashed into the corner of a board.