Implanting pets with a microchip is becoming standard for most pet owners. But just how well do those chips work?

For Lois Wilson it works just fine. Her dog Bullet is more than a just a pet, he’s been a form of therapy for her since she lost her husband two years ago.

“I’ve had Bullet about three years. My husband got him right before he passed away with a heart attack and he’s been my little buddy ever since,” she said.

To make sure she can always find her buddy, Wilson had him implanted with a microchip.

It’s a device that gives out a frequency and has a number that will lead to her contact information.

“I wouldn’t have a dog without one because you invest a lot of time with your dog and a lot of money and you definitely want to make sure he’s safe,” she said.

But sometimes the chip doesn't work.

Just this week the Hillsborough County Sheriff’s cattle dog "Doc" went missing. And when a vet scanned the lost pooch, no chip showed up.

Veterinarian Donna McWilliams says it could've been a number of things.

“There are occasions where we know a chip is implanted and maybe for whatever reason the frequency is no longer giving off so then when the scanner is wanded or waived over the animal, no identification is noted,” McWilliams said.

The chip may have also moved. But in most cases, the microchip does its job. And that's enough to give Lois Wilson the security of knowing her dog "Bullet" will be returned if he's ever lost.

Veterinarians say one of the common misconceptions about the micro chip is that it has a GPS. it does not. It will only scan and give a number to track down its owner.