Mine are both head butts as well. I was sleeping with Bunny and she had her head under my chin. She sneezed and nailed me splitting my lip. My husband woke up to me crying with blood running down my chin.
The second time I was sitting on the bed, bent over a little while putting on my shoe. Jazz was chasing Bunny and as she jumped on the bed she head butted me in my forehead. That was extremely painful and I really thought I was going to pass out but fortunately did not. I had a nasty blue goose egg for a bit.
Jazz, Shiloh Shepherd, 4.5 yrs old, CGC HIC
Bunny, GSD X, 7.5 years old