"I guess you could call them best friends; sisters. They came out at the exact same time. They've been together every single day for five years," said Courtney Laxton, who owns the horses.
Two weeks ago, Laxton got a call from a neighbor saying something was wrong.
"She said, 'Well, you have a horse down. Some of the other horses are around her, and she's not moving. She's just staying still.'"
Laxton rushed out to the ranch and found Mitzi dead on the ground.
Her horse, who was perfectly healthy 24 hours earlier, now had a deep cut right between the eyes.
The veterinarian told the family it looked like someone hit her with a hammer.
"It cut her scalp, and it cracked her skull with the same line as the crack in her skin, and it went straight to her brain," said Laxton.
The family had to carry Mitzi's body past Spirit on the way to bury her.
"She started running up and down that fence line, almost like she wanted to get out of that corral to go see Mitzi. It was just really hard," said Laxton.
Now, the family is offering a $10,000 reward.
They're hoping to find who did this, so they can protect the animals who are still around.
If you have information, please call the Collin County Sheriff's Department at 972-547-5100 or (metro) 972-424-4797.
