I would avoid avocado at all costs. I once tried growing an avocado tree indoors and my dog ate the small seedling down to the root. She showed no ill effects but I researched the plant's (and fruit's) toxicity. I found that other than to humans all parts of the plant and fruit are highly toxic to most domestic and wild animals.
"Avocado: Avocadoes are high in fat content and can trigger an upset stomach, vomiting or even pancreatitis. Avocado contains a toxic element called persin, which can damage heart, lung and other tissue in many animals." (
http://www.selfgrowth.com/articles/Toxic_Foods_for_Dogs.html)
"The avocado fruit is toxic to most birds. Even a nibble of your Aunt Millie's Guacamole could kill your house pet. Use caution when growing miniatures indoors." (
http://davesgarden.com/pf/atgo/2092/)
"Ingestion of avocado ( Persea americana ) has been associated with myocardial necrosis in mammals and birds and with sterile mastitis in lactating mammals. Cattle, goats, horses, mice, rabbits, guinea pigs, rats, sheep, budgerigars, canaries, cockatiels, ostriches, chickens, turkeys, and fish are susceptible. Caged birds appear more sensitive to the effects of avocado, while chickens and turkeys appear more resistant. A single case report exists of 2 dogs developing myocardial damage secondary to avocado ingestion."
(
http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/211102.htm)
