So awful for the owners too. It reminded me of the time I went to collect my last cat, Jones, from the vet. He was only in for some dental work but the nurse brought out the wrong cat! Didn't even look like Jones either. When I told her, she looked mortified and went off to get mine - then she came back with no cat, saying that the vet wanted to speak to me. I went frantic, I really thought they'd done something to him! Those few minutes of waiting for the vet to come out felt like an hour (fortunately she only wanted to tell me that he was still drowsy from the anaesthetic).