Microchipping provides permanent identification that dramatically improves reunion rates for lost animals and is mandatory for dogs in the UK — but welfare benefits extend beyond individual reunion to population-level outcomes.
Microchipping prevents the welfare harm of prolonged shelter stays, euthanasia of animals whose owners are untraceable, and the distress of both animal and owner during separation. The brief discomfort of chip implantation is trivially outweighed by the lifetime protection it provides. Maintaining up-to-date database registration is as important as the chip itself — an outdated address defeats the purpose of the identification system.