Foods That Are Toxic To or Just-Plain-Bad for Dogs. Can Dogs Eat& Alcohol Can cause intoxication, coma, and death; Avocado The fruit, pit and plant are all toxic. The toxic ingredient in avocado is called persin. They can cause difficulty breathing and fluid accumulation in the chest, abdomen and heart, vomiting, diarrhea, death, inflammation of mammary glands, cardiac failure, respiratory distress, generalized congestion, abdominal enlargement.