In the previous installment of this excerpt from the new book Equine ER, Piaff, a Dutch warmblood, was diagnosed with a devastating case of EPM that was worsening despite treatment. His owner proposed treating him with the human drug interferon as a last resort, a decision her vet supported. Below, the final installment:

The interferon was ordered Friday, but couldn’t arrive until Saturday. I found Dr. Stephen Reed, Piaff’s vet at Rood & Riddle Equine Hospital, in the admissions building Saturday morning waiting for the medication. It was supposed to be there by 10:30 a.m. and wasn’t. He was upset. “The client is looking at me expecting me to do something,” he said. “I’m really discouraged.” He went down to the barn to check on the horse. The winter’s first snow had come the night before, and the rooftops of the light brown barns were frosted; they looked like gingerbread barns. The cold was bullying.

In the barn, Piaff leaned against the wall. He looked like a war victim. The pressure sore on his right hindquarter was bigger, the skin now gray and flaking off. His right hoof was in what’s called a soft ride boot for support because of concerns about laminitis Ð he was leaning on his left side too much, putting little weight on the right. The pressure sore under his armpit now looked like a shark bite; occasionally he tried to lick it. He was now having respiratory problems. The night before I had read a magazine article about the rise in America’s fondness for pets. It said the French call their dogs btes de chagrin Ð beasts of sorrow, recognizing that to love a dog is eventually to mourn it. To my eyes, Piaff seemed to be turning into a horse of sorrow.

Reed needed to leave. He had promised his wife and out-of-town family that he’d spend time with them that weekend, actually since Thursday, and had barely done it. Like many veterinarians, he was in trouble with the ones he loved over his work schedule. He’d have his intern, Dr. Birthe Pegel, give the horse the medication when it came. But just as he was driving out, he got a call from the pharmacy that the interferon had arrived