Dog nutrient requirements: new knowledge

Dog nutrition was based on anecdotal knowledge from domestication until the beginning of last century. In 1943, McCay, in his book “Nutrition of the dog” quoted published studies and underlined that there was a real lack of information on this topic; more so than for other species. The result of this was that many animals grew old quickly and died early. The last 30 years have been characterised by a substantial increase in research into dog nutrition, particularly concerning nutritional requirements. The National Research Council (NRC) of the United States, considering this new information, has developed a new edition of Nutrient Requirements of the dog and cat. When comparing the four editions of this book (issued in 1972, 1974, 1985 and 2003), several differences, both in form and in substance, are noticed. The earlier editions supplied general advice, while the 1985 edition specified minimum requirements of essential nutrients. Both these systems have advantages and disadvantages: improvements in the new edition include determination of minimum levels (to avoid lacks) and maximum levels (to avoid toxicity) of different nutrients and energy and providing a safety range. This concept is already being applied by pet food companies, but misunderstandings are still common about energy requirements. The main doubt is related to maintenance energy requirements (energy consumed by an adult animal with moderate physical activity in thermic neutrality conditions). Different results have been found by authors in this area. These differences are due, in part, to the extraordinary heterogeneity among canine breeds; only horses are almost comparable. For example, weight can vary between 1 and 100 kg; the coat can be very long or almost nonexistent; and character and spontaneous physical activity are highly variable. Finally, it is important to consider the life style imposed on the animal by the owner. The aim of this paper is to compare the different systems for evaluating nutrient requirements, to obtain general rules useful for practical feeding and nutrition of dogs.