I had something similar happen to a three year old.
Cut off part of his hoof and punctured a secondary artery.
He spent three nights at the large animal vet facility who took excellent care of of him.
He was filled not only with antibiotics but given the all important tetanus shot.
When I brought the lad home on the fourth day, I was armed with meds, wraps, and detailed instructions. He healed but it took me a lot of follow-up labor and a lot of ancillaries.
I haven’t read this entire thread so I have lost track of who is doing what for the horse but they had better be doing something PDQ before they end up losing him,
Sitting on their arses won’t accomplish anything — that horse needed to see a vet the minute that happened 50 miles away or not.
I had to haul my horse 34 hard, back country roads miles with my husband running interference in the car, and pray he didn’t bleed to death on the way there.
This is why people without horse trailers should have a backup plan that includes someone with a horse trailer.