This year seems to be a drought year.
One of the relatively overlooked problems for a horse is Fungi. There are many, many different types of fungi out there and, while not exact, a common thread can be found in a lot of them. Dust.
The dry conditions are a breeding ground for fungi (not so much molds) and can be easily ingested by a horse as it picks at morsels in a pasture. A common haven for fungi is in feces. I'm learning about this as I write because one of my horses got it.
On a recent ride he was super agitated and I was trying to find the cause ? It felt like his mouth ... then his stomach ... then I was sure I was in for a rodeo ..... but all the while he kept "looking" behind him. Once I (thankfully) got him back to the trailer, I noticed very small bumps on his hinds and face. Hives ?? Stress ?? Nervousness ??
I called my vet and had him looked over. He got a clean bill of health. Photic Syndrome came up in conversation and, that night, I pored over information about that. That led me to many other possible causes - but none that really exactly fit. In short, I was fairly sure what it wasn't but stumped when it came to what it was.
Last week, I mentioned it to a lady and described the symptoms, reactions and 'bumps'.
"He's got a fungus".
I came home and looked up Fungi in horses. There are dozens, and while I was unable (without blood screening) to determine which fungus he had, I now knew what I was looking at. Among other symptoms, the fungus becomes super agitating while the horse is exercising and, with my horse, this caused his hind quarters and face to be inflamed. That explained his "ready to blow' demeanor.
Two suggestions were given to me. A topical application that took a bit longer than expected to work (but did) and to put a trace amount of apple cider vinegar in the water as a mild preventative to fungi in the stomach. I did both and ten days later that boy is ready to 'rock n' roll' in the mountains again.
This may, or may not, be an isolated case, but it was a new one on me. And it may be something we see more of as the summer progresses. Just an FYI.