The gator likely ate the horse, which was about the size of a Labrador retriever, she said.
"Don't mess with Nana", said Cochran, laughing as she spoke with a reporter.
Livingston Mayor Judy Cochran believes the gator she found on her family ranch along the Trinity River in Goodrich, Texas, is responsible for her miniature horse who went missing three years ago, she told ABC Houston station KTRK-TV.
Polk County is one of only 12 in Texas with an alligator hunting season, she said, and its limits gave her barely a 20-day window to take care of business, between September 10-30.
Residents in Polk County are only permitted to kill alligators 20 days out of the year, according to KTRK-TV.
The mayor of Livingston, Texas, was in a meeting when she received a call that the gator had taken the bait on a hook.
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"That's a monster", her son-in-law, Scott Hughes, can be heard saying over a video he posted to Facebook of Cochran aiming her shotgun at the animal.
Judy Cochran, a great-grandmother and mayor of a small town in Texas, finally got her gator.
"The horse just disappeared, so we're thinking the gator got it", said Cochran.
But Mrs Cochran said she had a permit and met all legal requirements. "None of him will go to waste".
The excited great-grandmother plans to process the 12-foot long alligator by having the head mounted, ridgeback part of the tail in her office, make boots from the gator's stomach and eat the meat with her family.