Madeleine, I'm going to agree and disagree with you. Most people don't feed raw, and they don't know what kefir is, let alone have it in their refrigerator. But, everyone knows how to cook rice. Rice stops diarrhea. I don't have a problem using it medicinally.
However, we need to think about how and why it stops diarrhea. I think it gums up the works, so to speak. We certainly don't want this on a regular basis. I do not feed rice but if the dogs get some in leftovers I don't worry about it, and at least it doesn't give them the runs. Grains, as you stated, are not natural in a carnivore's diet or in ours. Our ancestors fermented grain into a beer, which changes the grain's physical properties, improving its digestibility and nutrient level. Carnivores simply do not eat grain.
Just because feral dogs eat pasta at the dump does not mean that it's good for them, and it certainly isn't the best. Feral dogs at the dump do not stay alive because they are eating pasta, it's simply a filler. They are also eating other garbage and possibly hunting rats and mice.
Madeleine, maybe you could start another thread explaining what kefir, spinurale, etc. are.