Absolutely, guinea pigs can enjoy blueberries, but moderation is key! Fresh, organic blueberries are best since they are free from pesticides that could potentially harm your little friend. However, you should avoid feeding them any dried or processed blueberries which may contain added sugars or preservatives that are not good for guinea pigs. Blueberry leaves and stems should not be offered to guinea pigs. They can be tough to digest and might cause some digestive upset. As for the benefits, blueberries are packed with antioxidants and vitamin C, which are excellent for guinea pigs, as their bodies can't produce vitamin C on their own. This makes blueberries a great choice for an occasional treat. Regarding serving sizes, moderation is again crucial. For a small guinea pig (under 1.5 pounds), one to two blueberries once or twice a week is sufficient. An average-sized guinea pig can handle up to three blueberries two or three times a week, while a larger guinea pig (over 2.5 pounds) might enjoy three to four blueberries up to three times a week. Always watch how your pet reacts to new foods and adjust accordingly. Introducing anything new into your pet's diet should be done slowly to monitor any adverse effects.