It was a horse named Betsy, after all, that Isaacson credits with helping to heal his son Rowan, who was diagnosed with autism just after his second birthday in 2004. The toddler's uncommunicative, tantrum-ridden state devastated his concerned parents.
"Rowan would have as many as 12 tantrums a day," Isaacson, 42, told ABCNews.com. "Everyone knows what a regular toddler tantrum is, but add a deep distress where the child is just inconsolable and unable to communicate the pain that they're in."
"All you can do is try to hold them and stop them from hurting themselves," Isaacson said of he and his wife Kristin's consistent attempts to soothe their son. "When you see your child suffering like that it tears you to pieces."
Isaacson said that he quickly learned that Rowan, who is now 7 years old, would calm down if he was allowed to roam and explore the woods outside the family's home in Elgin, Texas, just outside of Austin.
"One day Rowan went where I wasn't expecting him to go and before I could grab him he was in my neighbor's pasture, right next to a group of horses that happened to be grazing right there," remembers Isaacson. "Rowan dived right under the horse -- every parent's worst nightmare."
While Isaacson said he expected his small son to be trampled by the horse, what came next was life-changing.
"The old boss mare -- who we'd later learn was named Betsy -- walked over and pushed the other horses off," said Isaacson. "Betsy dropped her head and started making a chewing sound that horse lovers know as a sign of acceptance."
"I've never seen a horse offer that to a babbling two-and-a-half-year-old," he said. "Rowan and Betsy obviously had some sort of connection."
It was that connection that Isaacson would later discover held the key to his son's happiness. Isaacson, a horse trainer for most of his adult life, began horseback riding with Rowan, finding that the rocking rhythm of the animal's stride soothed his son. Throughout his horseback riding, Rowan continued with more orthodox therapies, including applied behavioral analysis, one of the most commonly used therapies for kids with autism.
"Whenever he was on a horse he wouldn't tantrum," said Isaacson. "When I put him on Betsy that would be the only time his tantrums would stop, any other situation and he could turn at any point. We wanted to keep him on a horse as long as possible."
In the summer of 2007 when the boy was 5, Isaacson and his family went on a horseback trip in Mongolia, spending four weeks where Rowan was happiest: on the back of a horse.
"Before we went to Mongolia, Rowan was incontinent and subject to neurological fits and tantrums and was cut off from his peers," said Isaacson. "We came back with a child that was toilet trained and no longer having tantrums. He made his first friend on that trip, too."
"It was the most extraordinary thing," he said.
"Rowan is not cured of autism, but healing is a different thing," said Isaacson, who has chronicled his son's adventure in a book titled "The Horse Boy" and a 2009 film called "Over the Hills and Far Away." "He was healed of these three terrible dysfunctions that were impairing his and our quality of life."