Amigo as he was found by owner Gary Sanderson.
"It's been a rough road," Amigo's owner, Gary Sanderson, told Horsetalk from Luttrell, a town of about 2600 people in Tennessee.
Amigo, an accomplished endurance horse, suffered his terrible injury on the night of January 16 in his 110-acre pasture.
Sanderson had gone up to the pasture around 4.20pm the following day and was surprised to see Amigo standing near the barn.
"I said, 'what are you doing up here?' He whinnied at me. I walked around to the side of him and saw the stick in his side," Sanderson said.
Amigo had somehow been impaled by a five-centimetre wide branch, which entered his left side, snapped two ribs and penetrated his chest cavity, coming to rest against a lung.
Sanderson said the pasture was hilly and had a lot of trees, so it was possible Amigo had slipped and impaled himself in the process. However, there had been high winds overnight and he suspects a tree may have fallen on him.
The vet called out to see Amigo's injury suggested euthanasia might be the best course.
Sanderson wanted to give Amigo a chance at life - and that chance was 45 minutes away, at the Large Animal Clinic at the University of Tennessee.
Amigo, he says, was a seriously ill horse. "His gums were already blue," recalls Sanderson. "His breath was toxic."
He recounted how Amigo loaded on his horse trailer for the drive to the clinic, and even managed to eat some hay on the way.
Amigo unloaded and made his way to the clinic under his own steam, where he was given a local anaesthetic and underwent surgery to remove the 90-centimetre long branch.
Amigo stood through an hour or so of surgery, during which vets not only removed the stick, but excised damaged and rotting tissue from the wound.
The degree of necrotic tissue led the veterinarian who performed the surgery, Dr Nick Frank, to suspect the injury may have been suffered some 12 hours before Sanderson found him.
He had last checked on Amigo around 10.20pm on the night of the accident, meaning Amigo may have been impaled only an hour or two later.
"The stick didn't puncture his lung, but it was laying against it," Sanderson said. "His left lung collapsed during surgery, but they were able to reinflate it."
Amigo was given only a 2 per cent chance of survival after the surgery, with bacterial infection proving a life-threatening hurdle.
But Amigo fought back. The odds climbed to 25 per cent and they are now around 50 per cent.
"We're not out of the woods yet," says Sanderson. "But I do feel we've turned a corner."
Amigo, he says, is still the sickest horse at the clinic.
His wound was left open and staff pack it daily with gauze. "The wound is knitting. They are talking about sewing it up."
Amigo required drainage tubes in each lung and has gone through 11 bags of plasma from two different donor horses.
"He had an allergic reaction, causing his platelets to attack the donated plasma instead of the infections," Sanderson explained. Amigo's platelet count fell so low that it threatened to kill him, but again, he fought back.
A blood clot went to his brain and he collapsed and suffered a seizure. Staff ran to his aid. Amigo came round and stood back up.
Laminitis and colic have been an ever-present risk, but Amigo has mercifully remained free of both, although at one point his caregivers feared he was about to suffer a bout of colic.
"He is putting up the good fight," says Sanderson. "He is one amazing boy with one amazing will to live!"
His treatment has even included time in a hyperbaric chamber, to aid his healing.
"I think he has probably turned the corner. Whether he will run endurance again, we just don't know. Dr Frank said amazing things can happen."
However, Amigo's injuries mean he will finish with lung scarring, which may affect his endurance ability.
"I don't know whether he will [race again]. I don't really care. I just want him to come home."
Amigo is enjoying daily light exercise, but is still being fed twice daily through a tube to ensure he gets enough protein. Earlier, he was being tube-fed three times a day.
Amigo's recovery is being watched with interest by more than 2600 fans on his Facebook page. Sanderson says all those who leave a comment under the "Just fans" section receive a personal reply. It takes about an hour a day.
"These are people who are praying for my horse. They all get an answer," he says.
Amigo's care comes at considerable cost. His medical bills are likely to be upwards of $US13,000 to $US15,000.
"I'm willing to go into debt for him. He wants to live. I am not going to give up on him."
Sanderson says he is putting his faith in God, and is prepared to go without in order to meet his horse's medical bills. "It will be a setback, but we'll deal with it."
He says the clinic staff have pulled out all the stops to give Amigo the best possible shot at survival.
However, real risks remain. Bacterial infections continue to pose a serious problem, and staff regularly undertake blood tests to tweak what Sanderson calls Amigo's antibiotic potion. He has had at least six or seven different antibiotics, to his knowledge.
Sanderson said he bought Amigo in 2005 when the horse was aged five. He bought the gelding off his girlfriend, Kara Disbrow, who had owned him since he was two.
Amigo and a fellow equine partner in crime were causing too much damage to her property - fences and such like - and she felt Sanderson should have him.
Amigo was, he said, the cheapest horse you could hope to buy. The deal cost him a slice of cheesecake and some Mountain Dew (a softdrink) at a fast-food restaurant.
He began riding Amigo in endurance in 2005-2006 and the horse has 770 miles to his credit, most of it logged over 50-mile races. "He took to it like a duck to water."
In fields of 38 to 40, he has consistently finished in the top 10, and has a best time over 50 miles of 3 hours and 40 minutes.
Sanderson, who works in environmental safety and health in the nearby city of Oak Ridge, says Amigo owes his survival to his will to survive, and the care and attention he has received from the staff at the University of Tennessee.
Amigo may have lost weight in his fight for recovery, but Sanderson says he can see the old spark back in him. "His spirit is back up again."
That's just the kind of news Amigo's many fans will want to hear.
You can follow Amigo's care and progress here.
Cheques can be made out to:
University of TN Large Animal Clinic Patient #211197 Amigo
They can be sent to:
University of TN c/o Business office
2407 River Drive
Knoxville, TN 37996