I've seen police grade OC spray not work with a damn on both dogs and humans. Yes, sometimes it works great, but not always. I would bet the same with a bear.
Personally, I would take a fire extinguisher over OC spray for any dog.
I had to spray an attacking German Shepherd dog with a 325 gram can of bear spray. I hit him as he came in at 8' with a 2 second burst. It hit him in the face and he broke off his charge and ran away.




















































