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 pet’s body needs, and why, here are the six essential classes of nutrients fundamental for healthy living:

1. Water is the most important nutrient. Essential to life, water accounts for between 60 to 70 percent of an adult pet’s body weight. While food may help meet some of your pet's water needs (dry food has up to 10 percent moisture, while canned food has up to 78 percent moisture), pets need to have fresh clean water available to them at all times. A deficiency of water may have serious repercussions for pets: a 10-percent decrease in body water can cause serious illness, while a 15-percent loss can result in death.

2. Proteins are the basic building blocks for cells, tissues, organs, enzymes, hormones and antibodies, and are essential for growth, maintenance, reproduction and repair. Proteins can be obtained from a number of sources. Animal-based proteins such as chicken, lamb, turkey, beef, fish and egg have complete amino acid profiles. (Please note: Do not give your pet raw eggs. Raw egg white contains avidin, an anti-vitamin that interferes with the metabolism of fats, glucose, amino acids and energy.) Protein is also found in vegetables, cereals and soy, but these are considered incomplete proteins.Amino acids are the building blocks of proteins, and are divided into essential and non-essential amino acids.- Essential amino acids cannot be synthesized by the animal in sufficient quantities and MUST be supplied in the diet. Essential amino acids include arginine, methionine, histidine, phenylalanine, isoleucine, threonine, leucine, tryptophan, lysine, and valine.-Non-essential amino acids can be synthesized by your pet and are not needed in the diet.

3. Fats are the most concentrated form of food energy, providing your pet with more than twice the energy of proteins or carbohydrates. Fats are essential in the structure of cells and are needed for the production of some hormones. They are required for absorption and utilization of fat-soluble vitamins. Fats provide the body insulation and protection for internal organs. Essential fatty acids must be provided in a pet’s diet because they cannot be synthesized by a dog in sufficient amounts. A deficiency of essential fatty acids may result in reduced growth or increased skin problems. Linoleic acid is an essential fatty acid for dogs.-Omega-6 and omega-3 fatty acids play a vital role in healing inflammation. Replacing some omega-6 with omega-3 fatty acids can lessen an inflammatory reaction—whether it is in the skin (due to allergies), the joints (from arthritis), the intestines (from inflammatory bowel disease) or even in the kidneys (from progressive renal failure).The optimal ratio of omega-6 to omega-3 fatty acids for dogs is between 5 and 10 to 1.Please note: It is impossible to accurately determine the fatty acid ratio of a diet if the owner prepares home-cooked foods. If a dog is to benefit from the effects of these fatty acid ratios, he must be fed a fixed-formula food that guarantees these ratios.

4. Carbohydrates provide energy for the body’s tissues, play a vital role in the health of the intestine, and are likely to be important for reproduction. While there is no minimum carbohydrate requirement, there is a minimum glucose requirement necessary to supply energy to critical organs (i.e. the brain). Fibers are kinds of carbohydrates that modify the mix of the bacterial population in the small intestine, which can help manage chronic diarrhea. For dogs to obtain the most benefit from fiber, the fiber source must be moderately fermentable. Fiber sources that have low fermentability (e.g. cellulose) result in poor development and less surface area of the intestinal mucosa. Highly fermentable fibers can produce gases and by-products that can lead to flatulence and excess mucus. Moderately fermentable fibers—including beet pulp, which is commonly used in both dog foods—are best, as they promote a healthy gut while avoiding the undesirable side effects. Other examples of moderately fermentable fibers include brans (corn, rice and wheat) and wheat middlings. Foods that are high in fiber are not good for dogs with high energy requirements, such as those who are young and growing.

5. Vitamins are catalysts for enzyme reactions. Tiny amounts of vitamins are essential to dogs for normal metabolic functioning. Most vitamins cannot be synthesized in the body, and therefore are essential in the diet.-When feeding a complete and balanced diet, it is unnecessary to give a vitamin supplement unless a specific vitamin deficiency is diagnosed by a veterinarian. Due to the practice of over supplementation, hypervitaminosis—poisoning due to excess vitamins—is more common these days than hypovitaminosis, or vitamin deficiency! Excess vitamin A may result in bone and joint pain, brittle bones and dry skin. Excess vitamin D may result in very dense bones, soft tissue calcification and joint calcification.

6. Minerals are inorganic compounds that are not metabolized and yield no energy. These nutrients cannot be synthesized by animals and must be provided in the diet. In general, minerals are most important as structural constituents of bones and teeth, for maintaining fluid balance and for their involvement in many metabolic reactions.