The adverse effect of one medication (donepezil) was misdiagnosed as a novel medical condition (gastrointestinal distress), which lead to further medication use (Pepto-Bismol). This could have been prevented by correctly identifying the cause and decreasing the donepezil dose. He would have never needed the Pepto-Bismol in the first place.
Use Pepto Bismol to help with an upset stomach and vomiting. Use this only for dogs, though; it contains an aspirin-like substance, which is bad for cats. The dose for a dog (either liquid or tablets) is a child's dose for every 40 pounds of body weight every six hours. For example: A 10-pound dog would receive one-quarter of a child's dose, and an 80-pound dog would receive twice the amount of a child's dose.