WSVN — Every day thousands of animals are lost. Their owners search for them and never find them.

Claudia was lucky Diesel jumped out of a car window and disappeared. Four days later she got a call to come and get your dog.

Diesel is back home because of a microchip the size of a grain of rice that was put under his skin.

Dr. Michael Fusco: "It's a very tiny capsule. It goes under the skin. It doesnt irritate. It usually never hurts."

And when a veterinarian checks an animal a scanner should reveal the owner.

Dr. Michael Fusco: "If they escape, if they get lost, it's a good way to prove legal ownership and a good way to insure that most likely you will get your pet back."

The chip enabled fusco to re-unite Claudia and Diesel.

Dr. Michael Fusco: "This is the way it works in a perfect world."

These tears show you the way it works. In a perfect world, these tears show you how it also works in the real world.

Katherine Coombs: "I don't want this to happen to anyone else. We don't think this should have to happen to anyone else ever."

The coombs cat O'malley had a microchip. Earlier this year, he got out an open door. Five weeks later a Broward County animal shelter technician picked him up, scanned him and concluded O'malley did not have a chip.

Debbie Coombs: "They said that the scanner was broken when they picked him up and they had him for four days. They put him to sleep."

23,000 animals a year are brought into the Broward County Animal Shelter. If they have a chip, most of the time it shows up, but not in O'malleys case.

Officer Stan Harvey: "It's not fullproof. In that chips will occasionally wander in the animal or migrate in the body. The scanner itself can malfunction. There can be a problem with the batteries. So there are it's not 100 percent.

Not foolproof for so many reasons.

Patrick Fraser: "This is one of my dogs. Gabby has a chip, but there are at least eight companies that sell microchips. Each only keeps track of their own customers. Some of their scanners won't recognize another company's chip, and if it does, it wont tell you who that owner is, and that's assuming the owner keeps updating their phone number and address when they register the chip."

Daniella Ramos: "A lot of pet owners get the microchip but they never take it home and register it. If its not registered it's like not having a chip at all. There is no information to get back to, we can't find the owner."

And if the owner can't be found, and the animal ends up at the shelter it could wind up dead. Thats why the animal experts consider the chip a backup that your pet should have a collar and tag.

Lisa Mendheim: "It let's people know that might find your pet. It is indeed an owned animal it's not some stray. In Broward both your cat and your dog need to be registered and have the pet license on their collar."

The Coombs bought a chip and registered it. It did not save O'malleys life…

Debbie Coombs: "It's a piece of equipment. If it's not used properly by the people that get the animal then it's useless it's a waste of money."

The Acostas bought a chip and registered it it brought Diesel back home to them.

Claudia Acosta: "Yes, yes. I tell people if you have your dog you love your dog you have to do it please put a microchip because he is home again."

Sometimes it bring them home, sometimes it doesnt.