Nothing thing not mentioned here... bear spray.

The pepper spray that comes in 9 to 12 oz cans, maybe $40 to $60.

I know it works on loose ranging dogs, I've used it at least six times in the last twelve years (while walking my own dogs). Like I said elsewhere here today; two rotts, two pits, a boxer and a big yellow mutt. Advertised range 10 to 30 feet, basically a non-lethal projectile weapon. As much as anything that 20ft plus blast seems to startle the dog and snap it out of attack mode. It IS expensive to replace every time but still much cheaper than vets or doctors.

Never had to pull it out when confronted by a human but I imagine it would have deterrent value.

Mike