Boo was always a quiet cat who never, ever meowed — but that changed when his family's house began to fill with a deadly gas.
The black-and-white house cat was adopted by his Ohio family about seven years ago, WKRC reported, and he may have been saving those meows for when his family needed him most.
"He never meows. He usually just squeaks or doesn't meow at all," Ariana Kecskes told WKRC. "It's actually kind of a joke in our family."
But on Tuesday, when Boo's family was asleep in their beds, he began to meow — a lot.
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David Kecskes told FOX19 that as his family was sleeping, Boo began meowing so loudly that it woke everyone up.
"I woke up slowly and my wife had woken up at the same time and Ariana had woken up from her bedroom. . . and we just saw Boo fall and pass out right here," he told KTVU. "And then Ariana came out of her room, it's her cat kind of, and she passed out right here."
Ariana Kecskes told WKRC that Boo was stumbling down their hallway, but he continued to meow.
"He passed out so many times trying to wake us all up and that's just amazing because he's never really meowed before," she said. "It's like he's been waiting his whole life to do this one heroic thing."
But Boo wasn't the only cat who helped save the Kecskes family.
While Boo was passed out, the family's other cat "walked in and kind of revived him," WKRC reported. "Our other cat kind of sniffed him like, 'Hey, get up, '" Ariana Kecskes said.
After everyone was awake, they rushed out of the house and David Kecskes called 911 at about 7:30 a.m. on Tuesday.
"My daughter fainted in the hallway, my son fainted on the back porch and our cat fainted in the living room," he told 911, according to FOX19. "And I'm dizzy and my mom's dizzy. And my wife's dizzy."
Fire crews who responded detected a potentially-lethal level of carbon monoxide in the house, KTVU reported. The family was taken to the hospital.
"Had this situation gone on much longer the outcome could have been different," the assistant Green Township fire chief told FOX19. "It's colorless, it's odorless, it's tasteless, so it is a silent, it's a silent killer if you will."
Fire investigators said the carbon monoxide was leaking from a malfunctioning boiler.
More than 400 Americans die from unintentional carbon monoxide poisoning that is not linked to fires every year, according to the Centers for Disease Control and Prevention. More than 20,000 people visit the emergency room with carbon monoxide poisoning each year, and more than 4,000 are hospitalized.
The CDC recommends installing a carbon monoxide detector in your home and checking the batteries twice a year.