Did you ever watch the film "Dean Spanley"? When the Dean gets a tot of Imperial Tokay, he recalls his existence as a dog. I believe the original story was by Lord Dunsany and he obviously knew dogs very well. Peter O' Toole stars as an embittered old man who cannot get over the death of his first son and does not get on with his second. But acquaintance with the Dean and his recovered memories eventually brings about a happy reconciliation. Highly recommend and available very cheaply from Amazon. People to whom I have given it have bought copies for their friends.
I don't know the film. Thanks for pointing it out. I shall try to track it down.