Supplements are needed when feeding commercial pet foods because the nutrients are lost in the processing.

If you feed an AAFCO feeding-trial proven pet food, no nutritional supplementation is needed. Pet foods are complete and balanced, meaning they contain all of the known nutrients required by cats or dogs in the proper concentration and have been shown to be bioavailable. The heat involved in processing pet foods does destroy some vitamins, but more so vitamins are destroyed while the product sits on the shelf or in storage. However, most vitamins are only partially destroyed, and pet food manufacturers know exactly how much extra vitamin to add prior to processing to account for expected losses.

In fact, the final pet food product contains between five and ten times more of each vitamin than is required by the cat or dog. Additionally, pet food processing does not destroy minerals; they may actually become more readily available as the food is made more digestible by cooking. Therefore, adding a vitamin or mineral supplement to your pet’s diet is not necessary. Most supplements in fact contain only a fraction of the pet’s actual daily requirement and do not correct most deficiencies.

If you have more specific questions - Ask the Nutritionist.