Michelle Olson and her husband had taken 8-year-old Sophie to Suburbia North Animal Hospital in Houston, Texas, for her regular checkup and rabies vaccination.
Everything seemed fine, until they received a frightening call on their drive home.
The couple rushed back to the hospital to try and save their beloved cat.
"I immediately took her out of her cat carrier and I held her, talked to her, because I knew that was going to be the last thing she would remember," Olson said. "I knew she wasn't going to come back at that point. I just knew it. She pretty much was dying in my arms."
Suburbia North Animal Hospital did not return CNN's request for comment.
Olson said while the hospital staff was extremely sorrowful and apologetic, it was simply an "accident that should have never happened."