Bear spray is the highest pain causing agent, can be stronger than level 3 human spray.
Bear 1-2% measured as major capsacinoids
Level III 1-1.33%
Level II 0.5- 1
Dog 0.35-1
Level I 0.5
1.52% MC in “Wildfire 18%” in one assay.
https://www.safetytechnology.org/wp-content/uploads/WILDFIRE-18-Pepper-Spray.pdf
The Scoville heat units (SHU) advertised in all brands of sprays refer to the base resin compound (e.g., 3 million advertised for Wildfire 18%). The assay shows what actually comes out in the aerosol: “242,000” for Wildfire 18%, very high compared to others. The test for Fox Labs showed 84,000 SHU.
The OC percentage is also important, though. One consideration for the production of animal sprays is the effort to avoid causing animals more pain than necessary to deter them. I distrust those who promote and regulate animal sprays because of the contemporary prevailing perception that the welfare of an animal (especially a bear or dog) is more important than that of a human being.