We don't know what is wrong, but he's not quite himself. I hadn't seen him since this morning, but that wasn't anything unusual until it got to be dinnertime and he hadn't come in. When it got to bedtime and he hadn't appeared, I started to worry a bit. A and I called him, and he didn't come, but Pounce did. I thought maybe I heard something, though, so after the kids were in bed I got a flashlight and checked under the deck. Shadow has a favorite cool spot under there, in amongst the ivy - a patch of bare dirt where he can keep cool.
I brought him in, and checked him over as best I could. I didn't feel any problems, but he didn't want to head into the kitchen to eat. That is unusual. Usually he would head in to eat if he hadn't been in in several hours - or at least would head into the kitchen when I went in there.
He did jump off the chair and then back on a few minutes later, so he seems to be moving ok, if not speedily. I brought him one of his treats and he sniffed it, but didn't eat it.
At this point, I called the vet (of course, what I got was a phone number for an emergency vet). The on-call vet is not anywhere near here (of course not, that would be too handy!). They didn't have any real helpful advice, but said I could either bring him in tonight or take him to our vet in the morning. D wasn't home yet at this point, so I couldn't leave. Once he got home a few minutes later, we both checked him out - still no problems we can find.
I had asked the vet if there were any reasons not to give Shadow food or water and they couldn't think of any. So we gave him a bit of water with a syringe. He wasn't wild about it, but didn't mind too much. I feel better, as I worry he could be dehydrated. Dr. Google seems to say that it would take more than 12 hours without water to cause any real problems.
At this point, I think we're going to wait until morning. Shadow thought about jumping into my lap, but didn't - he took himself over to lie in front of the AC. That's another of his favorite spots in this hot weather. He seems to be resting comfortably (and isn't throwing up his water - that's a good sign).
Looks like we'll be heading to the vet's in the morning, though. Even if he's feeling ok in the morning, he's due for his shots.