I agree with Sannah(how she is so wise, I'll never know)

I don't think it's child abuse for you, coz you weren't forced to do it and you could and did walk away.
I do think it was animal cruelty-- but I am VERY soft hearted when it comes to all animals-- I can't even use mouse traps that snap the little mouse's neck.......
I think since it wasn't a pet of the family-- but a wild rodent, probably your dad saw it as a menace, something that perhaps carries diseases. I believe some people don't regard those types of animals(wild, rodent types) to be on the same level as pets like dogs, cats and such.

I'm sorry for the squirrel, from your posts-- it sounds like your dad liked to sometimes show "power" over other things..... could have been from low self-esteem.

peace to you
fins