CHATTANOOGA (WRCB) -- After waiting 10 days to be reunited with his dog, a local college student learned the family's pet had been euthanized by mistake.

The Lab mix was being held at McKamey Animal Center, where administrators say a paperwork mix up led to the dog's death.

"My mom always told me, everybody has that one dog, and Zion is that one dog for you," says Matthew Sadler.

Matt Sadler adopted the three-year-old Lab mix when he was just a puppy.

"That was my best friend," Sadler says. "He was there for me through my parents' divorce and a lot of really hard tough times in my life."

It was hard for Matt when Zion was quarantined last week, after jumping on a pizza delivery driver.

"The lady didn't want to press charges, it wasn't anything serious, but the law has a 10-day quarantine period," he says.

Because Zion was a month past due on his yearly rabies vaccine, he was held for the full 10 days at McKamey Animal Center.

Thursday, Matt eagerly returned to the facility to take Zion home.

"She says, ‘I'm sorry, Matt, we accidentally euthanized your dog'," Sadler says.

"We've made a horrible, terrible mistake," Karen Walsh says. "There is no worse mistake a shelter can make than that."

Executive Director Karen Walsh says two employees missed a step filing paperwork.

When the quarantine ended, despite calls and visits from Matt, it was not known that Zion was to be reclaimed. He was euthanized in error.

With teary eyes, Walsh explained how devastated her staff is by the mistake that she calls an isolated incident.

"We apologize from the bottoms of our hearts," Walsh says. "This is not what we do. We've had over 32,000 animals come through the center, and this kind of mistake just can't be explained away."

"It makes me feel good that they care," Sadler says. "But at the same time it contradicts the fact that if they cared so much they would take the necessary administrative steps to prevent stuff like this from happening."

McKamey has offered to cremate Zion, and allow Matt to adopt any dog he chooses.

Matt says he just wants assurance this won't happen again.

"I'd definitely make sure you get your rabies vaccination, and make sure they are documenting things if your dog does get picked up."

According to Walsh, McKamey euthanizes on average about five dogs a week. Most of those have shown aggression.

Walsh says the two employees who made the mistake will go through extensive retraining.

Walsh also adds that the center offers discounted rabies vaccines every Wednesday for all pet owners.