That is a mess!
Please please get some Resolve Wound
as this will encourage the healing faster than anything I have, in 60 years, ever come across. ResolveWound | Prevent and Eliminate Proud Flesh In Horses
I am about to post update pictures of a wound a yearling had. Yes, it would heal but, my vet thought that it would be alt least Christmas before he could even think of skin grafting.
Thanks to Resolve Wound
there is barely a scar - and I had to clip the hair for the scar to show!