I have used pure Lavender Essential Oil on proud flesh bed sores & on Coronet weeping which worked well getting rid of infection & helping granular healing in the open flesh wound.

Caroline Ingraham is an animal Essential Oil Specialist - take a look at her website- https://www.carolineingraham.com/product-category/essential-oils/

One suggestion was to try a few drops in an extra bucket of water. Providing choice for the horse to drink including normal drinking water. In the end I had 3 different buckets with different oils in it for different issues. They decided which, if any, they wanted to drink , how much of it & then eventually didn’t bother with it when done. 

 As advised I let her lick from my hand a drop of lavender oil in a drop of water, or let her smell it if she wanted to. She vigorously rubbed the right side of her her nose in it every time I checked on her . This continued for many days gradually getting less, until not wanting it anymore. I’ve found since if she goes through a painful episode I repeat the offering & she takes it up- ignoring it when she starts improving feeling. It seems to cheer her up /reassure her so I use it as part of my first aid.

I’ve not shared before as it’s a bit ‘out there’ but it seems to do something for my donkey & pony & makes me feel less useless.