An angry reindeer knocked down its Cambridgeshire owner and trampled her after running loose near a road, an ambulance service spokeswoman said.
Kay Davies was reportedly leading the animal to a pen at Churchfield Farm, Whittlesey, when the incident happened.
Ms Davies owns the firm Wedding Horses, which supplies horses and reindeer for weddings and Christmas parties.
She was taken to hospital suffering head, chest and leg injuries. The reindeer was put to sleep by a vet.
A spokeswoman for the East of England Ambulance Service said: "We were called at 1142 BST on Tuesday.
"Reports were of a reindeer on the loose and, initially, that the woman had injuries to her head, chest, groin, legs and ribs, but these turned out to be superficial.
"The crew needed to call for urgent back-up, as the animal was very angry and wouldn't let them near the patient.
"But it was eventually captured and the woman treated at the scene.
"She was later conveyed to hospital."
A Cambridgeshire Police spokesman said: "The animal was running loose near to the road and was thought to belong to a nearby farm.
"Officers found the reindeer and called a vet, who put the animal to sleep."