There's been a few comments like this about horses 'left' in fields, no rugs coats and no stimulation.
My horse is the happiest and most relaxed he's ever been since being permanently turned out in a field with a small herd.
They are checked daily, have water checked and topped (and will drink out of a puddle instead when it's fresh and clean!) And the field poo picked/fencing checked. They get the farrier 4 times a year on average and are wormed according to worm counts and have an annual vet check when vaccs are due.
Two are not rugged because they don't need it, they grow adequate coats for the climate (mine is actually 3/4 tb) and have natural shelter as well as a structure. We feed hay in winter if they seem hungry (using their energy to keep warm and therefore start to lose condition when there's nothing in the grass) and they do have a really large field with hilly parts, flat areas and some different ground to walk over.
They are really low maintenance and the change in my horse, even since not rugging him and allowing his body's natural mechanisms to work with regards to eating almost constantly, losing and gaining weight naturally with the seasons and the grass being constantly grazed, but not over grazed so there's much less risk of laminitis or colic in spring, has been amazing.
He's happy, relaxed and more importantly, healthy and a different horse from the bolshy, grumpy and most importantly, stressed stabled horse I had for years. We haven't had a vet except for the annual routine for the 5 years he's a been out, it was at least twice a year for laminitis or colic, injury or a virus etc in the 10 years previous.
I always thought he loved his stable because he wanted to be in as soon as he saw me, he was routine bound and got stressed when he was expecting something to happen. He doesn't have that now.
It's taken me back to that feeling of someone who just loved looking at these magnificent animals and being around them instead of being all caught up in what we 'should' do to supposedly enjoy our horses.
They need to be managed but managed well and with relatively little intervention, they can thrive. None of them have vices (my horse used to box walk, bang his door, another crib, another weave)
Compare that to a racehorse cooped up in a stable 20 odd hours a day, clipped, high energy food and restricted forage, restricted turn out, little opportunity to experience natural herd behaviour, high impact exercise to make sure they're super fit and rugged. I think many people are 'schooled' into thinking that that is well cared for, because it costs a lot more than the way my horse lives, but it's about as far from natural as you can get.
But, I'm still cynical about the motivation not only of the protestors, but of many others claiming to have animal welfare at heart - I bet in 6 months time there'll be posts about fireworks and their effect on horses (and other animals) and I would reckon that many making those claims and some of these strongly worded comments here under different user names will be defending their 'fun' of having fireworks and any issues faced by the animals are the issue of the owners. Animal welfare is a drum to beat for some.