Can dogs eat Avocado? Dogs should not eat avocado – both fruit and plant contain a substance called persin that is toxic to many animals. Dogs and cats are resistant to persin, but can still suffer an upset stomach. The seed is a danger due to its size and can get stuck in a dog’s esophagus, stomach, or intestines. Other animals such as cattle, horses, birds, and rodents can suffer organ failure and die from avocados. Birds are particularly sensitive.