Olivia Yendall, 19, feared her Welsh Cob, April, would be put down when its hoof was almost severed by barbed wire.
But while April was in veterinary hospital, visiting equine experts used a specialist machine to treat the wound and the animal is now recovering.
Ms Yendall said it was "a miracle" the horse survived.
Following the incident in May, veterinary wound specialists Prof Derek Knottenbelt and Georgie Hollies, who had been visiting Seadown animal hospital in Hythe, used the specialist saline pump - called a Versajet - which can clean inside the most serious wounds without causing further damage.
Prof Knottenbelt said: "In reality, the horse had no right to survive - the tendons, tendon sheath, joints, ligaments all seemed to be damaged in that heel area. We either had to do something or put April down."
He said the "very sophisticated" equipment powered saline through a small hose "busting and lifting off every bit of bacteria and leaving everything else that is intact, untouched".
Seadown equine vet Breda McDonagh said it had been a "stroke of really good luck" that Prof Knottenbelt and Mr Hollies had been on site, adding that the treatment had been the "turning point" in the horse's recovery.
Ms Yendall, from Southampton, praised the veterinary hospital and wound specialists, adding: "We're currently following Seadown instructions and on an eight-week programme of box rest, walking April on the lead rein four to six times a day.
"It's been a miracle that April has survived and they have all given her the very best chance of recovery."
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