I respect the advice of ShopForum members and know you are well researched - - -
This is a (approximately) 1989 Beagle.

Well, somewhere between 12 and 15 years old - my Mom's dog - which I now have for nursing back to health.
Usually is very active and healthy. He went out with me while I was doing some field mowing work and ran off. Probably with some other dogs since it is hunting season. Anyway, he got lost and was gone over two very cold nights. When he got back, he was sick and stiff-muscled.
He ate at first, but developed a tough breathing problem (like a badly swollen throat) and stopped eating. I have him inside the house in a warm room and his breathing problem has cleared up.
He drinks plenty of water and is not dehydrated. He gets up and walks around - took a good walk outside this afternoon.
Won't eat.
I have force-fed a little salted chicken-noodle soup broth and some gravy from canned dog food. Sometimes that has had the tendency to upset his stomach and he later throws up (much later, maybe five to eight hours).
Does not have a bloated stomach that I can tell.
Has not eaten anything that was not force-fed for nearly a week.
How serious is this? Any recommendations for anything good to force down him? He seems to be making good progress but I know he has GOT to have nourishment....
I'm also interested in any good canine health-care web sites you can recommend....
Thanks,
Ken300D