Do not be surprised if there is a fair amount of blood
I think anyone who has not seen one “unzippered” should be forewarned that there can be a fair amount of blood.
Our mare just needed a little bit of local anesthetic. We did it in the barn aisle with a tarp underneath to minimize clean up.
My surgeon husband was a bit disgusted we paid for the vet to do it, it really is not that technically challenging. I have always been concerned re how far to cut superiorly (ie towards the rectum) - vet told me two big person finger widths is where you stop the incision. If using a scalpel, will need to use free hand to ensure not cutting deeper or past the Caslick.
We did apply some topical antibacterial ointment to the edges a couple of times per day for about a week so it would not close back up.
Good luck!