A while back my neighbor's pitbull attached a second dog they had. The son came to my house asking for help. I had previously purchased pepper spray for my daughters, so I grabbed two of the spray canisters and ran next door. Dumped both canisters point blank into the pitbull's face.... Didn't faze him at all.
They were small 'keychain' canisters, so might not have been as 'potent' as heavier duty stuff.
By that time a couple policemen arrived. One had an ultrasonic device that when he pointed it at the pitbull and pressed the button the dog went directly into 'pussycat' mode. Stopped and cowered on the ground. Really amazing.
FWIW, when I told the officers I was getting ready to get my piston and put the dog down, they told me... 'You don't want to do that... if you do, you'll always be the guy that shot their dog' . No BS about discharging a firearm in a residential area etc. This was in Kaneohe.
Good guys, those officers.
aloha,
Ed