I also find that folks who work with animals find animal things not gross, but "human" things gross....my friend who is a zookeeper is one of these folks
Heck, how many folks here have no qualms about cleaning a bunch of chicken poo, but if that was human....yeah. Moving on
The way workers comp works, it's either insurance or workers comp that pays for it. So, if insurance covered all but $1100, then it probably paid $4000 or so (if you have a common 80/20 plan). Your boss paid whatever he pays, but if you change this to comp, he will have to pay the whole $5000+, not the insurance after amount. That can be brutal for a small business. Some small places have to pay this out of their pocket
You can ask him to help you out with the outstanding amount, but I doubt they will go for you hitting them for workers comp, when insurance has already paid for the surgery. Even more unlikely if they provide gloves and you choose to not use them. Impossible if you didn't follow worker comp rules from the get go (going to a company choice doctor, filing it appropriately etc). If your workplace has under 5 employees, they most likely don't have worker comp insurance, just liability, and any payments would have to come from the company pocket.
Claiming comp and using insurance is double dipping the system and I think can be considered fraud.
I've had to use workers comp before - it's a frustrating and annoying system. I don't recommend it (fell and broke an ankle at work).
Assuming a "he" boss, because it's early. Swap for "she" if it's a woman.