Well, Bay did fine during the afternoon, browsing on dry weeds in the pasture, but this evening once the medication wore off, he started looking dumpy and laying down again. He even refused to eat grain that was offered to him, which I have never seen him do before. So we called the vet back.
After checking his (Bay's) vital signs again (which are still fairly normal) and administering another dosage of medicine and a slight sedative, he (the vet) put on a long glove and proceeded to perform a rectal examination... inserting his arm up to the shoulder, checking for obstructions, pulling out lumps of poo and checking the consistency. He (the vet) said it (the poo) seemed a little harder and drier than is normal, like he's (Bay's) getting a touch dehydrated. They (the horses) have plenty of water that we (ecurbh and Hair) keep filled up, but it (the weather) has been so dang hot lately.
He (the vet) pulled out a 6-foot section of plastic hose, got it lubed up, and started feeding it (the tube) up through his (Bay's) nose, all the way down to the stomach. Bay seemed rather nonplussed at the whole procedure, but then, if I was in his situation, I would be too. Anyway, he (the vet) pumped in a couple gallons of an oily-watery mixture to try to clear out whatever has him blocked up.
Looks good so far, he (Bay) ate a couple bites of grain and nibbled some hay, and hasn't seemed to be in a hurry to lay back down. We'll see if he eats breakfast in the morning, and take it from there. He (the vet) isn't worried about a serious episode tonight, so we shouldn't have to stay up with him (Bay) all night.
Thanks for your prayers!
I'm glad Bay is doing better. I'm also glad I'm not a vet. ;-)