This summer, she reunited with Opie — thanks to a Craigslist ad.
When Pool first learned of Opie's disappearance, she reported it to the authorities and embarked on her own investigation.
A neighbour told her he saw a horse trailer at Pool's father's place that night. He thought it was hers, MSNBC reports.
Pool visited every house alone Interstate 10, asking if anyone recognized the white-and-tan horse in the fliers was she handing out.
"When he was missing, I posted his photo on every website I could find," Pool told Your Houston News. "I handed out flyers all around San Antonio and I hoped for the best."
She posted a Opie's photo and stats on NetPosse.com, the website for Stolen Horse International, checking the site frequently for leads on stolen or recovered horses.
She found nothing.
"There was no sign of him and I was heartbroken," Pool told MSNBC. "I had to explain to my kids that there are people in the world who take things that don't belong to them. They were scared one of the other horses was going to get taken. I said, 'We'll find him, we won't stop looking.'"
Pool's father, Andrew, was confident that Opie hadn't been slaughtered: "He's too valuable for that."
Years went by. Pool divorced and left Texas for Arkansas. Still, she never gave up the hope that she would see her horse again.
A few weeks ago, Debi Metcalfe, the woman behind Stolen Horse International, called Pool.
"We found your horse," she said, adding, "I'm 150 per cent sure."
Opie had been listed for sale on Craigslist. A Dayton, Texas, woman named Della Brade was selling the horse, renamed War Bonnet, that her pastor had given her eight years earlier. The pastor told her that the horse had been wandering on the I-10, and that he couldn't do anything with the shy animal exhibiting signs of abuse.
"War Bonnet was scared, wild-eyed and thin. I let him go in a small pasture for two days…once we joined up and started building up some trust, I decided to saddle him and was going to tie him to a hitching post. That's when he went down to his knees and began shaking. I realized that the horse had been through some serious abuse," said Brade. "He was deathly afraid of ropes of any kind."
Brade worked with the horse and "he blossomed into a wonderful riding horse." She decided to sell the horse this summer, after months of deliberation, so he could bless another family as he did theirs.
Just because I was selling him doesn't mean I didn't love him," she told the Houston Chronicle.
Deanna Bordelon answered the Craigslist ad and asked Brade questions about War Bonnet's background. She went home and looked up the story, expecting to find something about a wandering horse. Instead, Stolen Horse International's site, NetPosse.com, popped up.
She found a thumbnail of Opie on the site. It was identical to the photo of the Craigslist horse she had seen earlier.
Bordelon immediately called Debi Metcalfe. Within a day, Pool had been contacted, the officer first assigned to the case confirmed the theft, and contract cowboys from the sheriff's department seized Opie from Brade, who was unaware that the horse had been stolen.
"It was a good day when all the pieces of the puzzle fell in place quickly," Metcalfe told MSNBC. "It rarely happens like that."
Pool drove through the night to be reunited with her horse.
"I will see him, kiss his face and blow in his nose soon. The shattered dreams I had are being put back piece by piece and glued together all with the help of two AMAZING people....the tipster DeAnna and Debi with Stolen Horse International - netposse.com THANK YOU!" Pool told the group after Opie was located.
Watch their touching reunion here.
Pool and her boyfriend are currently looking to buy a property well-suited for Opie and their two other horses, which are currently boarding at a friend's property.
"I plan to use Opie to train other young girls to ride. I think he will like that," Pool told Your Houston News.
[ More Good News: Cancer and stroke survivor to take on gruelling obstacle course challenge ]
(Photo courtesy Michelle Pool)