Are avocados harmful to dogs?

The leaves, fruit, seeds and bark of avocados contain persin, which can cause vomiting and diarrhea in dogs, and more serious signs in other animals due to a wide range in sensitivity across species. Birds, horses and rodents are especially sensitive to avocado toxicity.

How much avocado can hurt a dog?

One avocado should be fine for a medium-size dog, but two or three in a day? That is far too many avocados for a dog. Also, keep in mind the nutritional make-up of avocados. One medium-sized avocado contains roughly 320 calories and 29 grams of fat.