Have you tried a spray in conditioner? Alpaca isn’t so hard to take care of. Most dust comes out with brushing and if you would like to wash it, you certainly can. The hair washes easily in any temperature water. The important things to know, to resist felting, is to keep the water temperature the same throughout and not to agitate while washing. I let mine air dry. In this weather, you should have no problems there-lol!
If you are having a great deal of shedding are you making sure that all your hair is lined up even at the knot end. Or, perhap, you are cutting the hair when you are threading it through the scalp. I’ve done this before during lock and loop using fishing line to thread the needle. The fishing line was cutting some of the hairs…not all, but it sure made it shed. Also, have you tried a spray in conditioner? You might have little tangles that break as you brush the hair.
The hair can be combed or brushes, as you wish. Just do NOT comb/brush it WET!!
I hope this helps.