Hair thinning/loss on pink skinned horses

[casskerf]

My horses as well as my coaches horses hair seems to be thinning across their bodies. It isn’t coming out in clumps at all, and just seemed to gradually happen for us to really notice that we can see their pink skin through the hair now. They are both pintos, mine only has a medicine hat, and hers has some more brown patches, but both are losing hair on the pink skinned areas. Both horses wear flysheets to prevent sunburn and also wear flymasks in the day, which my horse seems to also be losing hair around her eyes.
This is the first time this has happened for both horses! Both horses had allergic reactions, we think from different things, though(mine had recently started a new supplement, once taken off the reaction cleared up). Both got hives that turned to scabs, but my coaches horse had a worse reaction
They both are somewhat more itchy than normal as well.
We aren’t quite too sure what this could be? Our thoughts have been dry skin from the heat, it’s been quite hot this summer for them. And we are getting a lot of smoke from the northern BC fires. Or maybe even the flysheets are breaking the hairs causing the hair to thin.

I hope that all makes sense and I’ve posted this in the correct area! I’m new to the forums Ask anything if i’ve made this confusing!
Thanks!

[Scribbler]

This is the time of year horses start to shed their summer coats. My paint has lost hair around her eyes but you see black skin, a bit like Arabs when they shave and Vaseline them for shows.

[casskerf]

We know horses start shedding this time of year, but we have never been able to see this much pink on the before. And have both had these horses for multiple years. It’s very strange. If I can get a good picture I will post it asap!

[atr]

My appy is very pink and thin haired in his white parts right at the moment. He always does this to some extent, but this seems more than in the past. He seems to shed out a bit too much before he starts growing in the next layer. He’s getting a bit older, so I wondered if that was having an effect.

[candyappy]

My mare ( in my avatar) had that last year in places along her back. I had started using a non neoprene saddle pad and I think that had something to do with it.

It was not itchy but seemed sensitive to the touch.
I added a skin / coat supplement to her diet and it didn’t come back.