PlasticCabDriver
White dog poo was developed by the Ministry of Health during WW2. Dog owners were urged to add a tablespoonfull of Fuller's Earth to a dog's food, in order that the dog's stools would be more visible to pedestrians during blackouts.
The Ministry of Information published a poster, which shows an apoplectic Hitler, with his jackboot landing in a large, dark, steaming pile (a guilty looking Goering-faced Doberman pinscher cowers nearby), while a smiling Churchill is featured, deftly avoiding a neat, white deposit. Even after the War, people continued the habit of adding Fuller's Earth to dog food, but, with the introduction of tinned dog food, the custom died out.