I got a gallon of Neem oil several years ago. It is good for killing white flies on plants and ear nats on horses.
There were about twenty flies on one horses eyes and when I left only three were flying around her face .. I smear it about a half inch away from the eye .. in the ears .. best thing I've discovered. I was once told that if your horses didn't nicker when the shoe'er drove into your drive way .. fire them. Same thing on fly spray. I whistle in the evening and they come running from the far end of the pasture.
For cuts .. one quart squirt bottle half full of water and three tbl spoons of 3% hydrogen peroxide. Stops bleeding, no sting, cheap and cuts heal quick .. rear legs and feet of mustangs and kickers .. get them in a corner and squirt away. I was using a $20 herb compound that worked .. but I didn't want to waste it on kickers and read about this mixture.
If you get too far from the stone age .. things go haywire.