Well, I can tell you my dog went 14 days without food. She had several things wrong with her that I ended up taking her to the vet twice for. Even after both vet trips she STILL wouldn't eat, though she was and is taking water (I am presently dealing with this situation, this isn't something from the past). My dog, Coco, looked emaciated, like a dog you would see on that show with the animal cops that find homes with dogs that aren't being fed. Skin pulled tight into her rib cage.
Excepting, I have been trying to feed her - chicken; beef; dog biscuits; canned dog food; all kinds of treats that she always likes: wouldn't even think about it.
Yesterday, she could barely get up and when she did, she was wobbling and almost falling over.
That was enough for me. If you can force feed prisoners in jail, then by golly, I was going to force feed my dog and that's exactly what I did. Took half a can of dog food: a whole leg of chicken - meat and skin removed from the bone of course; some leftover chicken and rice casserole and dumped it all into a blender and also dumped a can of beef broth on top of it, salt free.
I let'er rip for a long time, wanted that concoction to be as watery as possible. Poured it into a large bowl, got out my turkey baster and proceeded to delve into unknown territory: basically shoving food down a dog's throat in the form of a liquid. Would she choke? Would she puke it back up? Well, I hoped not but I HAD to try, she was otherwise going to die of starvation. Several cups later and she was sitting there, looking at me.
I waited it out - 20 minutes, an hour, 2 hours. After 3 hours, I decided that she was not going to puke it up and also decided that if she was not going to eat tomorrow (which is today), I would do it all over again. Come home from work today and offered a smorgasbord of different types of food - none of it dog food, all human stuff that I KNOW would normally appeal to her. She would have none of it. I proceeded to make much more of the concoction today than yesterday. 20 minutes later, it's all down her throat. But to a dog, it tastes good, or it should anyway, it should all taste like chicken with rice.
BTW, yes the vet did blood panels at the animal hospital and tested the kidneys and whatever else - she was urinating blood - nothing turned up positive. She did an extremely severe urinal tract infection, which the antibiotics, after 2 days now, are finally getting in there and getting somewhere as the excessive bleeding has stopped. But it matters little if the dog survives the infection but dies due to starvation.
Anyway, she is holding down the rather large amount of liquid food I gave to her about an hour ago, and for that? Extremely happy doggy owner.