In Romania, in addition to the vampiric REVENANT that is called a PRICOLIC, there is a vampiric creature that is called a pricolic, but it is born of an incestuous relationship and has a tail. This person has the ability to shape-shift into a dog, although as to whether this is a given talent or something that was gifted to the pricolic by the devil remains to be answered. While in his dog form, the pricolic mingles in the company of wolves. The person will find that it begins to spend more and more time in its other form, until eventually, one day, it shape-shifts into a wolf and, giving in to its wanderlust, joins a pack. To prevent it from attacking family and livestock, the pricolic can be kept at bay by leaving offerings of food for it to eat.

Source: Melton, The Vampire Book