Trends in companion animal nutrition often reflect trends in human nutrition. Some keepers use a raw food (primary) diet for their animals, believing that it may provide better health benefits for their animals. Others, basing their diet on products of plant origin, will feed dogs a vegetarian or vegan diet. Recently, products containing protein from insects have become increasingly popular on the food market. Dog nutrition is very often related to the owner's lifestyle, which leads to nutritional mistakes that, if repeated over a long period of time, may cause behavioral disorders or diseases. Knowledge of the specificity of the digestive tract, digestive behavior and energy needs of a dog allows us to optimize the nutrition of this species. Current knowledge about the nutritional requirements of dogs is the result of decades of research, and dog nutrition should be based on it. Due to the constantly growing interest in dog nutrition among guardians, as well as the growing empathy towards companion animals, owners want to feed them well so that their animals live longer in the best possible condition. The article presents the nutritional requirements of dogs based on the recommendations of the National Research Council (NRC) and The European Pet Food Industry Federation (FEDIAF), and provides an up-to-date review of research on the optimal nutrition of dogs, especially in particularly demanding physiological or health phases/periods of their lives, with particular attention to indicators such as:: age, castration, obesity, pregnancy and lactation, or behavior.