Sam's home from the vet. He's on Metronidazole (aka Flagyl) for the next 6 days (at least), and Panacur for 3 days. Panacur (aka Febendazole) is a powder you mix with the dog's soft food, so Sam's getting canned food once a day for a while (he doesn't mind the taste of the Metronidazole in the food); Jacey gets to have the canned food, too, and she's delighted.
Panacur is used to fight parasites, and the fecal test from 18 May didn't show any signs of parasites. But Panacur also tends to give a quick kick to a dog's immune system, so in that sense it should be good for Sam.
The working theory is that the dogs picked up some bad bacteria from the chicken that sickened both of them in March. Jacey kicked the bad bugs, Sam didn't--quite. We need to get this under control before Sam suffers permanent damage (like thickening of the intestinal walls) that would cause more serious health issues. Inflammatory bowel disease in dogs can be a nightmare.
The Metronidazole can be extended if necessary, but if it seems not to be working, we'll change to Tylan (aka Tylosin). I'm hoping to avoid this since Tylan tastes nasty (so I've heard), and dogs hate it. It also is a powder, and if you can't get the dog to eat food you've mixed it in, you've got a problem getting it down a dog's throat. Determined pet owners have had to buy empty capsule shells and make their own pills for their dogs. I'm hoping we don't have to go that route.