The theory of blood-thirsty dogs terrorising the land is a longstanding one. They were most famously immortalised in the Sherlock Holmes mystery, 'The Hound of the Baskervilles', the vampire dog, or hellhound, appears from nowhere and with much ferocity and feeds off the living.

More shocking than you might think. A pack of the blood hounds have reportedly been killing goats and chickens in Texas, just to drink their blood, leaving the bodies untouched aside from some fang marks on the neck. Three dead dogs were discovered around the scene with blue skin, no hair and fang-like teeth. Scientists are currently testing to see if these dogs are a new breed or a mutation.