Most berries, but not all berries, are safe for dogs and are an excellent source of nutrients. Berries can be messy though so make sure you give them to dogs away from the carpets in your house. Berries contain antioxidants and can help boost the immune system for dogs. Strawberries have a high Vitamin C content and are great for your dog’s teeth. Of course you don’t want to give your dogs too many berries but keeping a bag of frozen berries in the house as treats are a great, healthy option for training.