So far, all the ones I've seen are external and require a largish (for small dogs) battery that has to be kept recharged. There's talk of small GPS chips like the ones used in cellphones being implanted, but I don't think anyone's marketed it yet for dogs. I'd do that in a heartbeat.
__________________ Mike ~ Doting Dad to Jillie, Harper, Molly, Cooper, Eddie (RIP), Lucy (RIP), Rusty (RIP) and Jack (RIP). Check us out on YouTube |