★★★★★
Depends on a location but dub the "thick" paste of ichthammol over the boil little bit bigger than the size of boil itself and put gauze over it and tape it up worked for me.
You can mix with itchamol & Neosporin 50/50 too , also you can apply iodine first then dry it and apply that itchamol & Neosporin over if you want.
Replace the gauze and re apply itchamols thick and generously then cover it with gauze again and tape it up. About 4 days and all the pus comes out & sticks to the gauze.
Get an itchamol in a jar for the horse. Because you gonna need it.