Purina PRO PLAN Medium Puppy with OPTISTART is a complete food for medium-sized puppies, formulated to develop their immune system and strengthen natural defences, while helping to maintain healthy joints for long-term health. It contains a combination of nutrients that supports an active lifestyle for your puppy. It is also suitable for pregnant or lactating bitches. OPTISTART helps to strengthen the puppy's natural defences to combat daily challenges, especially during the "immunity gap" in the first year of life, when the puppy is more vulnerable to infections and needs specific nutrition to develop strong teeth, muscles, and bones.