Pete The Vet: My dog is eating the post - what can I do?

Pete the Vet answers your questions

The post - an illicit part of a complete breakfast for dogs around the country

Our dog keeps running at the door and snatching the post as it comes in the door. I even ordered a felt detachable post box - but he chewed that up as it was delivered! What's the best way to dissuade him to do this - he is a Jug - part Jack Russell, part Pug. I can report that roaring at him and throwing the chewed up post at him does not work. 

- Caroline, Cork.