Prescription Diet™ b/d™ Canine is a complete pet food for the nutritional management of pets with behavioural changes associated with brain ageing. Key Benefits · With special antioxidants and omega-3 fatty acids to maintain brain function and improve learning ability in older dogs. · Reduced protein, salt and phosphorus to help maintain heart and kidney health in the older dog.. Please consult your vet for further information and guidance on what is best for your dog.