Per the USCCA information:
Per the reciprocity map" Pepper spray is Legal for personal self-defense under Michigan Penal Code (MCL 750.224d) for those 18+. The amount of pepper spray a person can possess is limited to 18 ounces or less. "
Two points from a non-attorney who speaks with attorneys and USCCA: 1. Any self-defense tool you feel you may need needs to be with you at all times, and you need to be well practiced and prepared with it; And 2, Planning to and using an agent, such as wasp spray, outside of its labeled usage will open the door to both statutory and civil issues.
In Michigan, pepper spray is legal to carry and use. It is easy to carry, and it has practice products available.
The owner of this dog is well aware that the animal is dangerous. They have paid a lot for the damages the dog has done. If the dog comes for you again, pepper spray it. If the owner becomes aggressive, you should already have 911 on the phone hearing the issue, and after watching the dog in pain the mere visual of the can still in your hand and aimed at them should settle things down quickly. If calm does not return, a dose at the human face will be helpful.