You could put a rock or something in there and use compressed fluid to propel the projectile at the dangerous animal. Maybe look into inexpensive gas canisters or chemicals that expand rapidly when struck and prepare individual containers with the rocks so you can swap them out quickly after use. Add on some small protrusions at the ends to help with getting the pipe lined up with the thing you want to hit too.

I think this idea could really catch on, will have to see whether there’s anything like that on the market already.