I can sure relate to having the vet on speed dial. I told my vet if he ever gets big enough to "go public and sell stock", I had better be in the top five of the first people he informs
Back in the early 80's my Morab had ragweed allergies. Thankfully I could keep his pasture clean but back then all I could do was keep his eyes clean and not do any trail riding until ragweed season was over. I couldn't even do much road-diding because some fields by the roads were polluted with rag weed.
Fast forward to today's world:
After we moved/retired to the Tennessee Valley, my now 18 yr old TWH developed dust/mold/pollen allergies to add to his oat/corn/soy intolerance - ain't it great?
I had him on TriHist for three seasons. It did help some but it seemed to amp him up and make a nut case out of him more than it helped his allergies.
Then I discovered Equine Science herbs4horses "allergy herbal blend". Equine Allergy Herbal Blend: stronger immune system for horses Herbal Remedies for Horses including Natural Equine Supplements for Laminitis and Founder in Horses- Herbs For Horses
This is the fourth summer Rusty has been on this stuff. Not only does it work miracles but it really mellows him out. He still itches because I don't think anything's going to be 100% given that we live in The Basin, a/k/a allergy purgatory BUT his problems have been reduced by 95%.
We're in the height of allergery pollution so, right now he's on 1-1/2 doses. Don, the owner of Equine Science, said it's ok to up him to a double dose if I have to. He is 16/1H and weighs around 1,150.
This stuff's expensive because it's pure. I also buy the Chastetree for my metabolic horses from this company, and I buy other stuff too - lol lol
They are honest, ethical, trustworthy and 99.9% of the time, I get my products practically before I hang the phone up. They're in Memphis, I'm several hours east below Nashville.
I use Bausch & Laumb saline solution for the horses, or just plain B&L eye water.
Vetericyn now makes an eye wash as well.
If your mare would wear one of those Guardian Fly Masks, and you could afford one, you might consider one of those until ragweed season passes.
Even though regular fly masks have a certain amount of UV protection, the Guardian is made specifically for that and for eye protection due to health issues. Meaning this type of mask would help keep the strain off her eyes Guardian Mask - Uveitis, Glaucoma, Cataracts, Eye Cancer & Eye Injuries
I am so wore out from all the health issues this weather has heaped upon us, metabolic issues, arthritis issues, all of which are exacerbated by the heat/humidity. Unless we get the Siberian winter of winters, I will be ecstatic for winter to get here. I've just about had IT - lol lol lol
I had thought winning the Big Fat Lottery and "summering" some place cooler like MN or VT would be the answer but I see the OP lives in MN so there goes that theory down the terlet