Blueberries are one of the better fruit treats you can give a dog. Safe, low in calories, bite-sized, and actually nutritious — antioxidants, vitamin C, vitamin K, fiber. Unlike some fruits that are "fine in moderation" mostly because they're not toxic, blueberries are the kind of treat where giving them occasionally has genuine upside.
Most dogs will eat blueberries off the ground or out of your hand without hesitation. A few dogs aren't impressed, which is fine — they're not for everyone.
Portion and practicality
A small handful — roughly 10–20 blueberries — is reasonable for a medium or large dog. They're low enough in sugar and calories that you have more flexibility here than with something like bananas or even strawberries. That said, too many at once will cause loose stools — the fiber adds up. Keep it to a reasonable amount per sitting.
Frozen blueberries work well too. They're a popular summer treat — small, cold, easy to toss a few out. For very small dogs, let them thaw slightly before serving, since a frozen blueberry is a bit more of a choking risk when it's completely solid.
Why they're a good choice for training
Blueberries are small enough to use as training rewards without adding a lot of calories to a session. If you're doing a 15-minute training session and using 20 treats, blueberries are a much better caloric choice than commercial treats — and most dogs respond well to them as rewards. They're not quite as high-value as something like cheese or meat, but for low-distraction training they work fine.
No prep, no cutting, no mess. Pull them straight from the bag. That alone makes them convenient.