Dried mare pee leaves yellow spots

[Tanga]

I'm not worried or anything, but just wondering. I couldn't find anything in a search. I'm supposing it has an association with being in season.

Right now I have three mares who seem perpetually in season and are unendingly flirting with the boys and peeing so much at them I'm surprised they are not dehydrated. The spots where the pee dries out sometimes have what looks like dried yellow powder, usually in a concentrated area. I assume it's something with hormones?

[piedmontfields]

I've had a few mares and have never noticed this. Curious to what others think!

p.s. My mare demonstrates that she is in season not by peeing excessively but by spooking excessively. She is trying to protect the next generation, I assume.

[Tanga]

It's interesting I can't find anything when searching. I don't see it all of the time, but have noticed it a lot lately. Since I have three in the same space, I'm assuming all three are doing it once in awhile. I'm assuming it's some hormone thing.

[Canyon]

When my geldings pee, their urine is clear yellow to start and ends up looking milky yellow at the end. I think this is normal, with calcium carbonate concentrated at the end of the void. When the urine dries on the pea (haha) gravel in their runs, there is a chalky yellow area where the milky urine landed. Is this kind of what you are seeing?