Thanks for the suggestions. Haven't seen it in about ten hours but last time I saw it the granulation had gone and it was starting to heal over a little on the edges. We've been hosing it morning and night and applying a diluted antibacterial spray (can't remember the name of it) three times a day. We tried using Vitamin A oil to quicken the healing process but it didn't apply well, so we asked around and people have suggested Manuka honey after it heals a bit more.
He's got quite a fiery personality so we still can't get close enough to get right in there. He's okay if you go reeeaaally slowly but as soon as you try and touch the wound he jumps 10ft.
The vet said depending on how it heals I can start riding him (just walking) in a week or two.
"We are the light, in a street of sparkless matches" - Shaun Diviney