Deer fur is very short and tight. I would say if you want it to be realistic looking, use a rough bristled paint brush and gently stroke the icing in one direction, starting from the bottom (as if you were putting fish scales, or roof shingles, so the next row overlaps - does that make sense?) HTH!
I also forgot to mention - you might want to color the icing brown, first, and then airbrush after you have your textured look. Airbrushing can give it more dimension, but if you do not have an airbrush it is not necessary.
it would be bc because fondant wont move as she is telling you
Sorry - yes, buttercream would be the best medium for a realistice fur look IMHO. Fondant is too smooth and it will look fake, airbrushed or not. You can use fondant for the antlers, eyes, nose and use impression mats for texture of those (or I have heard of people making their own "impression mats" using every day items that have the desired effect.) But for the fur I would highly recommend BC.
hi, i foudn this tutorial, will look for others. hth
http://family.go.com/contests/cake-recipes/cakes/deer-mount-8350/
http://www.flickr.com/photos/sandrascakes/3224435052/
It looks great! Looks like real fur! So how did you do it?
I'm glad this came up, I have some dress and boots cookies that need fur accents on them -- this info will help a lot!! Thanks for posting! 
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