The phrase "to lose a pet" means that a pet you loved and cared for has passed away or gone missing, and you are no longer able to be with them. Full definition
Our doctors and staff have reunited dozens of lost pets with their owners over the years, aided only by their microchip number. (aerowoodanimalhospital.com)
Over the years we've had some truly amazing stories of lost pets reunited with their owners. (lostmydoggy.com)
It's much harder for pet owners to find lost pets with no form of identification in place. (fresnohumane.org)