I would not wash my horses mane in this weather for anything, doubly so if she is outside. I just got my mothers gelding to keep for the winter and he has not seen a comb for about a year. I used cowboy majic detangler, I knew it was good but it worked great, took about an hour and a half.
Whew! What a relief! Haha deffinatly thought he was going to lose alot of length. Maybe this wont end in doomness after all
I just undid my mare's wind knots today and her mane is like a foot and a half long now! You can definitely do it without washing. I did half of them just by spraying a diluted detangler on them and pulling them apart with my fingers. When I got to the last one I just went ahead and washed it just because it was so dirty and dusty, but you wouldn't have to :) Here is her mane after I got a knot out!
Snuggle or Downy fabric softener diluted 50/50 in a spray bottle...works wonders and they smell great after.
I just got a draft mare and the top of her tail is absolutely solid matted. This past weekend I got her mane and forelock untangled, to which I then braided to keep clean. I am going to work on her tail this week! It was 21 today and a driving snow, can't wash, so she's filthy.
There is no need to wash just be prepared to spend some time untangling them. Most dreads can be easily sorted if you gently tease the tangles out with your fingers. Spray on the detangler if you want but I find if the mane gets wet it's harder to untangle.