It's frickin' CG deer.

This is not a plague, per se. At least not yet... However, I have yet to see a horror movie make good use deer in any way, shape, or form*. I understand that using live deer would be tricky and animatronics are too expensive, but good lord do CG deer just look awful. Like, "you really couldn't have just written this scene out of the movie?" awful. They always movie in a jerky, cartoony sort of manner that absolutely kills tension.

Two flicks that come to mind: I Am Legend and The Ring 2. Both films use CG deer, both deer scenes are cringeworthy (less so in the case of the former), and both movies would have been better off without them.

Bottom line: good horror producers say 'no' to deer.

*The Evil Dead 2 could be a noteworthy exception. However, its deer is more for darkly comedic effect to emphasize that Ash had lost his mind.