Nutrients are substances obtained from food and used by an animal as a source of energy and as part of the metabolic machinery necessary for maintenance and growth. Barring any special needs, illness-related deficiencies or instructions from your vet, your pets should be able to get all the nutrients they need from high-quality commercial pet foods, which are formulated with these special standards in mind. If you would like to learn about what your petβs body needs, and why, here are the six essential classes of nutrients fundamental for healthy living: