Didn't happen to me, but there's this story in the company about a first officer on a 747F who went for a walk and didn't return for a long time. When he finally did, he said that while he was on the main deck he found a dog, a sheperd that had managed to escape from his box. He then put that dog back into the box. The captain, checking the freight papers found out they didn't have a single sheperd on board - just wolves..