Avocado — Food safety facts
Feed with care · Dogs · full breakdown on the linked food page
The flesh is not strongly toxic to dogs or cats, but it is very high in fat and the pit can cause blockage. Never give the pit, skin or leaves.
Short answer
It's generally safe in very small amounts, but you should be careful. Avocado flesh is high in fat and can cause stomach upset or pancreatitis if too much is eaten. Watch for vomiting, diarrhea, or loss of appetite over the next day, and call your vet if you notice these signs.