I am sorry to hear about your child.

Sinker said a .22 caliber is plenty. I will confirm his statement as we've slaughtered cattle on our farm for years. The rottweiler has a very hard front skull plate and the bullet will get in there and rattle around a bit, and turn the brain into jelly. Or you can place the barrel inside his ear and bang.

Personally I would have found the nearest jug of gas and book of matches.

Also, see if anyone around you is Cambodian. I guarantee you they would take it off of your hands.