Personally I don't trim any whiskers from my horse and wouldn't under any circumstances.
I've heard removing feelers and whiskers is to a horse a similar feeling to that when you burn the pad of your finger and lose the feeling. I am not sure if it's true or not but you wouldnt cut the whiskers off a cat or a dog. In some countries doing so constitutes animal cruelty.
So in answer to your question I don't know but even if you could I wouldn't!!
It's part of the correct turnout for American Quarter Horses to be fully trimmed - ears, jaw, 'feelers'. I tend to do it as late as possible - if she's stabled at a show overnight, I leave it the morning of the class so's she's had chance to find her way round a strange stable.
I would only do it with a horse which was very quiet with clippers or use round ended scissors - not my favourite task but it never seems to worry my mare.
In the winter she is left completely natural, well until her 'beard' starts to get tangled in her noseband or curb chain!
