Cats can eat pecans, but it is not advisable to feed them to cats. Pecans are not toxic to cats, but they can cause health issues such as upset stomach, vomiting, diarrhea, and in some cases, choking or gastrointestinal blockage if swallowed whole. Pecans are high in fat, which can contribute to obesity and potentially lead to pancreatitis. They can also be contaminated with mold, which may cause serious health problems like neurological issues or liver damage. Additionally, there is a very small chance that a cat could be allergic to pecans. Overall, while pecans are not outright poisonous to cats, it is best not to feed them pecans or leave pecans where cats can find them to avoid these risks.