Is Avocado (persin) safe for dogs and cats?

All parts of the avocado plant (Persea americana) — leaves, fruit, seed, bark — contain persin, a fungicidal toxin produced by the plant as a defense mechanism. In dogs, the primary clinical concerns are: (1) GI toxicity — vomiting and diarrhea from fruit pulp consumption, dose-dependent; (2) myocardial damage — persin causes fluid accumulation in the thoracic cavity, pericardium, and abdomen (hydrops) in birds and some mammal species; the cardiac concern in dogs is less severe than in birds but has been documented in cases of large ingestion; (3) seed (pit) hazard — the large avocado seed poses a life-threatening mechanical obstruction risk if swallowed by dogs. The ASPCA APCC receives hundreds of avocado-related dog calls annually. Most dogs experience GI signs after consuming moderate amounts of flesh/peel; severe myocarditis is most commonly documented with very large quantities. The skin and leaves contain higher persin concentrations than the flesh. Guatemalan varieties are believed to be more toxic than West Indian varieties, though all should be treated as potentially hazardous to dogs.

Cats appear somewhat less susceptible to persin toxicity than dogs based on reported case frequency, but are still considered at risk from avocado ingestion. Cats are less likely to voluntarily consume avocado than dogs due to dietary preferences. When exposure occurs — typically from access to avocado pulp or guacamole — GI signs (vomiting, diarrhea) are the most common presentation. The cardiac concern documented in birds and reported in dogs at high exposures applies in principle to cats, but well-documented feline cardiac toxicity from avocado is less common in the veterinary literature. The avocado seed remains a GI obstruction hazard for cats as for dogs. Essential oil content in leaves and skin may contribute additional hepatotoxic risk in cats given their metabolic sensitivities. Exposure to concentrated avocado leaf or bark (e.g., herbalism contexts) may carry higher risk than incidental fruit flesh ingestion.