We do not monitor this page on a daily basis. If you are questioning your dog’s behavior, CALL YOUR VET! Foods That Are Toxic To or Just-Plain-Bad for Dogs. 1  Alcohol – Can cause intoxication, coma, and death. 2  Avocado – The fruit, pit and plant are all toxic.3  The toxic ingredient in avocado is called persin. Milk and other dairy products – Some adult dogs do not have sufficient amounts of the enzyme lactase, which breaks down the lactose in milk. 2  This can result in diarrhea. 3  Lactose-free milk products are available for pets.