I've seen this pic a couple of places. I think the photo is legit but its the way its posed that makes it appear out of proportion.

If you set your camera speed slow enough images in the distance will be in focus just like the images up close. Since photos are 2 dimensional, its hard to see that one image is closer than another image.

I think the hog in this picture is probably a normal boar at a normal distance from the camera. The man and the vehicle are not only several yards beyond the boar but downhill giving the illusion that the boar is much bigger than it actually is. Kind of like any picture where close images are big and distanct images appear small.

Just my two cents.