I was on my way back to Whiterun, near the area on the outskirts of town where there is a giant camp, and a little swamp/stream, and I noticed some mudcrabs had an unusual green hue to them. I killed them, and then Aela and I were attacked by a fox, whom was also slightly glowing green. I'm unsure as to whether or not this is a glitch or a bug? Or if other people have encountered this? The fox are usually non-aggressive animals in Skyrim, so...

Let me know?

I get this sometimes. I think they're being Spriggan'd. I could be wrong.

Spriggans will summon animals to fight for them and when they do they will have the greenish hue.

Edit: Ive actually encountered a dragon with this same effect, im not sure if it was part of the dragon and they reused a texture or it really was spriggand