Guinea pigs will eat almost anything put in their food bowl, but pumpkin seeds and other types of large seeds are choking hazards. While pumpkin seeds may be nutritionally dense, there are better things to feed a pet guinea pig.
Guinea pigs can subsist on a diet that's composed mostly of timothy hay. This hay not only aids digestion but provides the guinea pig with the nutrition it needs. Other acceptable foods include fresh fruits and vegetables like spinach, kale, lettuce, strawberries, tomatoes, cabbage and blueberries. Guinea pigs can have small amounts of fresh pumpkin a couple times a week, but all seeds should be removed.