If a dog is stolen and then bought in good faith by an unknowing person, or lost, the rightful owner has to pursue the matter in the civil courts. Many owners regard dogs as family members, so failure to return a dog should be made an offence, to make it easier to reunite dogs with their owners.
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Dogs are chipped with owner details, but this is not currently enough for you to be reunited. If a dog is lost or stolen and bought It becomes a civil matter to get them back. This should be changed.