Quinoa (cooked) — Food safety facts
Safe to share · Dogs · full breakdown on the linked food page
Plain cooked and rinsed quinoa is safe in small amounts — rinse first to remove saponins.
Short answer
Yes, that small amount of plain, cooked quinoa is safe for your dog. It's important that the quinoa was rinsed before cooking to remove natural saponins, which can irritate the stomach. As with any human food, it should only be an occasional, small addition to their regular diet. A little bit like this shouldn't cause any issues, but if your dog seems unusually thirsty or has loose stools later, it's a good idea to mention it to your vet.