When I got to the barn today I learned that Mezza had been lying down in the sun for more than 1 hour, and several people were concerned. I went out to have a look--it was really hot, and Mezza uses her shelter as a bathroom, so it's not unusual to see her lying down. However the temp today was about 100 degrees. Two friends of Dawn's (Mezza's owner) had been concerned enough to try giving Mezza water from a squirt bottle, but she wasn't getting up. I took her halter and went in. The barn manager showed up, and we checked her gums. She got right up with the halter on, so I took my hat off to listen to her gut. She promptly spread her legs and peed on it! Her gut sounded good, she didn't seem dehydrated, so I called Dawn and told her we'd like to give Mezza some electrolyte paste, and I took her into the barn where it was cooler to do that. After the paste, I wet her down with a sponge, and Dawn asked me to wet her pen down as well.
In the end, Mezza was fine--fared better than my hat, which had to be sprayed down too, but took twice as long to dry!
Jill and John (who board horses at the same barn) told me later this evening that their new mare had been put beside Mezza the evening before, sometime after I'd left the barn. Apparently Mezza had run a lot along the fence line between them, and Jill thinks Mezza could have been quite tired today.
I am not sure why Mezza's water got moved. I took note of the depth and will recheck tomorrow. She was doing that mouth tapping at the new mare today. Hopefully she's not intimidated by her. If she is, the water may need to be moved away from the shared fence line.
Tomorrow I'll get her out for a bit. We may do more water again. She was curious about the hose today and kept sticking her muzzle in the spray when I wet down her pen!