My dog was dying, perhaps from old age, he's about 12 years old. It refused to eat for 3 days and was dying. What I did was instead of using apple cider vinegar, I used ordinary vinegar about 2 tablespoon on the water and bathed the dog with pure vinegar. Within 2 hours, the dog defecated ... and was back to normal within 2-3 hours. I recommended my friend's dog who was dying from some kind of insecticide poisoning and recommended the same, the dog licked some vinegar and vomited, and was cured. So ordinary vinegar works just as well.
My friend's dog drank some bad water and she believed she needed to take both of her dogs to the vet which she could not afford, so I recomended she give them some ACV to drink and it helped them almost immediately.