That poor horse's neck and mane looks entirely covered in thistle heads. Mollie had some in her mane and tail recently, but I didn't find that "brushes and combs" would shift them. The only way I've found to get them out is to wriggle each one out with my fingers. It's tedious but combing would probably just cause a tangle.
I wonder whereabouts these poor dumped ponies are?
I seriously doubt the horses give a crap about how their manes and tails look. They'll be toasty and warm in winter coats, mudded and burred up to the max, I can't believe anyone is concerned for their welfare because they're grubby...they're HORSES!!