Bear-spray works on any mammal & is stronger than the pepper spray for use against mere humans.

Interesting reading on the subject:
http://www.absc.usgs.gov/research/brownbears/pepperspray/pepperspray.htm

BC boy recovering after being attacked by cougar in Washington state
http://ca.news.yahoo.com/s/capress/090903/national/cougar_attack_7