My cat was about 6 weeks old and I fed her some mashed avocado that I was using to prepare guacamole. About 45 minutes later she began acting very lethargic and inactive. Keep in mind, she's a crazy ninja kitty. So the lack of energy was a shock. I called an animal poison control and was told that avo fruit can cause digestive problems in cats & dogs, mainly because of high fat/oil content. There is a toxin concentrated in the skin/pit of avocado, that is also present in a more complex form in the fruit. Apparently dogs & cats have a mild sensitivity to the toxin in the fruit. The skin and pits however are dangerous (i.e. animal chews through skin for fruit.) Horses, goats, cows, etc.. are even more sensitive to the toxin and can even sicken from exposure to fruit.