The Jackalope is a very real creature. Here in South Dakota they can be seen all the time. What was originally a Jack Rabbit gets infected with the cottontail papilloma virus (aka: the "Shope papilloma virus" virus) and then it grows horns.

This is why I can't allow my little Havanese dog off the leash to catch one, so that she doesn't get infected with the virus and grow antlers, herself.

The image itself is romantisized, but the upshot is that Jackalopes are real.