Every device sold for finding a dog works on a different principle, and each one has a place where it stops working. Knowing which is which matters more than the price.
A microchip does not track a dog. The American Veterinary Medical Association states plainly that a chip is not a tracking device. It has no battery and no transmitter, and it surrenders its number only to a scanner held within a few inches of it. A chip identifies a dog that somebody else has already caught. But it can help reunite dogs and owners, especially if the dog is taken to a shelter where dogs are routinely scanned for chips. Having your dog chipped gives you a chance of reuniting.
An AirTag has no satellite receiver either. Apple says the tag sends out a Bluetooth signal that nearby iPhones and iPads pick up and relay back. On a crowded block, that works. On an empty road there is nobody to relay anything. In a city, it could be useful.
Cellular collars, the PetPhone among them, send a real alert the moment the dog crosses the line, over the same towers a phone uses. Where cell service is limited, so is the alert, and a warning that never arrives looks exactly like a dog that never left.
The fourth is marketed to dog trainers, hunters, and adventurers traveling over remote terrain. Garmin's Alpha collars talk straight to a handheld receiver over VHF radio, rated at roughly nine miles with no towers and no monthly fee. It costs from $300 to $1200 and it means carrying a second device on every walk. It is also the only one on the list that still works when there is nobody else around.
Rick Good spent ten years in the newspaper business, including with The News & Observer (Raleigh, NC) and The Greenville News (Greenville, SC). He co-wrote, with Melinda Coleman, Rutledge to Riley: Governors of South Carolina, 1776–Present (Published by The Greenville News), and is the author of Mind Games Trivia #1 (Amazon). He has recently spent 15 years creating original trivia content through Sounds Good Mobile Entertainment and continues that with his new company, SGME Software. He edits The Smart Reader’s money, real estate, and business coverage.