Yes, it can be dangerous for cats to eat pine needles from a Christmas tree. The needles are sharp and can puncture the cat's mouth or intestines, causing irritation and even serious illness. Additionally, the oils in the needles can be toxic if ingested in large amounts. It's important to keep a close eye on your cat around the tree and keep it out of reach if possible. If you see your cat chewing on the needles, remove them immediately and monitor for any signs of distress.