It could be some mythic creature from a countries lore or it could just be a piece of fiction. There are mythic animals attributed to the different elements and the wolf is a very popular animal, so I could see how someone could make such a concept up. A quick Google search finds a combination of quizzes to determine what element wolf you would be and people writing fiction involving them. The only other time I've come across this term is a faint memory of some fluffy spell posted on this site about conjuring an element wolf which implied that one could do the impossible and summon a flesh & blood wolf empowered by the chosen element. They say all myths are rooted in fact so someone may know much more about this as I rarely do research into myths myself as the only creature that matches this remotely I know of is the Japanese fox spirit which has recently surfaced in modern media.
The concept of a animal or a human having a element is quite ridiculous, for instance humans sometimes ask what is their element or somthing along those lines on this site, while all the responses clearly state that a human has no one element but is a mix of all the elements, but can have a dominant element, the same should go for animals, ofcorse some animals are associated with elements, but thats mostly like a fox is in a red like color so a fox is fire, the point is that animals according to me dont have a element