Nutritional requirements of the dog and cat: growth

The mass of an animal increases for a finite period after birth. This increase in mass is accompanied by differentiation and evolution of the shape and structure of various organs and apparatuses: consequently the different parts of the body grow to varying degrees, so that the proportions between them change gradually as the animal approaches maturity.

Each species and breed, just like each individual, has its own size in an adult state and, within certain limits, a characteristic growth rate. A proper diet enables an animal to reach its potential, genetically determined size. Optimal growth is, however, something more than reaching an adequate size, in that it must give rise to healthy, adult subjects that are capable of reproducing._¹ This aspect is of fundamental importance because the sensitivity of a growing animal to dietary imbalances and deficiencies is much greater than that of adult animals: thus, particular care must be given to designing diets for puppies. Furthermore, young animals usually have only very limited reserves of energy and nutrients given the high needs for these dictated by their growth. Gender, diet, genetics and environmental factors influence the trend of the growth curve and the body composition.

The growth rate is highest in the period of life from birth to weaning and gradually decreases until puberty; this decrease is progressively more marked after puberty until the growth arrest associated with reaching adulthood; the time taken for this process is, usually, directly proportional to the mass of the adult dog.

The neonatal puppy requires very digestible food (colostrum, milk and milk substitutes) because of the high nutritional requirements in proportion to the capacity of the digestive system. Since the composition of the animal’s body varies during growth (the water content decreases notably, the protein content also decreases but to a lesser extent, while the percentage of fat increases), the demand for different food stuffs required to achieve the weight increase also varies over time in relation to the growth rate and the composition of the increased weight accumulated.

It has already been mentioned how harmful food deficiencies and imbalances can be for growing puppies, but this is especially the case for dogs belonging to large breeds. Puppies of these breeds have a greater predisposition to developing orthopaedic disorders if their diet is excessive or deficient in energy, vitamin D, calcium or phosphorus or if it provides an imbalanced supply of calcium and phosphorus._²

It is, therefore, very important to calculate the energy requirements of a puppy in order not to under- or over-provide. As a basic rule it should be appreciated that a deficit in the energy supply slows the rate of growth but although the adult weight is, therefore, reached later, once reached it is the same as that of dogs that received a more energy-rich diet. In contrast, administration of an excess of energy is responsible for the development of skeletal pathologies._^5,6The methods of calculating energy requirements proposed by various authors do not always yield equivalent results, but nevertheless allow satisfactory outcomes to be obtained._^4,7,8 The data needed to calculate the requirements are:

• current weight of the puppy;
• the indicative weight of the dog once growth has been completed (the weight of the parents can be used, or the average weight of the breed);
• coefficients of multiplication of the metabolic weight, which vary depending on the stage of growth (Table 1).

Table 1. Changes in energy requirements during the growth of a dog. (*Multiplication factors of metabolic weight (body weight_^0.75) to use to obtain the energy requirement).

As far as concerns the cat, the lesser variability in size of this species simplifies the calculation of the energy requirements. It is, however, important to appreciate that there are currently few data available concerning breeds with a high adult weight (for example, Maine Coon). A broad rule is to supply 200 kcal/kg of body weight from weaning until the tenth month of life and then switch to the ration necessary for maintenance requirements._⁹

Table 2 and Table 4 report the minimum levels of the other nutrients for growing dogs and cats, respectively, as established by the AAFCO. The maintenance requirements can be referred to for the maximum levels. Given the predisposition of puppies of large breeds to develop orthopaedic disorders, there are specific values for the nutrient requirements for these breeds; these are summarised in Table 3.

Table 3. Recommended levels of nutrients for the growth of dogs of large breeds (per 1000 kcal of metabolisable energy (ME) or kg of dry matter._⁴

References

1. Ladetto G. Dispense di Nutrizione ed Alimentazione Animale. CUSL Facoltà di Medicina Veterinaria di Torino (2002).
2. Hazewinkel HAW. Nutrition in orthopedics. In: Disease mechanisms in small animal surgery (1993); Bojrab MS ed (2nd ed). Lea & Febiger, Philadelphia (USA): 1117-1128.
3. Association of American Feed Control Officials. Official Publication, 1999; 122-144
4. Biourge V., Sergheraent L., Pibot P. -Nutrition et croissance du chiot- Besoins particuliers des grandes races. Rec. Med. Vet., 1996, 172, 485-493.
5. Hazewinkel HAW- Skeletal disease. In « the Waltham Book of Clinical Nutrition of the dog and cat» Wills JM & Simpson K. W. Eds. Pergamon Press: Oxford. 1994, 395-424.
6. Kallfelz FA. e Dzanis DA.- Overnutrition: an epidemic problem in pet animal practice. Vet. Clin. North Am. Sm. An. Pract., 1989, 19 (3), 433-436.
7. National Research Council - Nutrient requirements of dogs . Washington DC: National Academy Press, 1985.
8. Paragon G., Grandjean D - Elaboration du plan de rationnament du chiot . Rec. Med. Vet. 1996, 172, 511-518.
9. Gross KL, Becvarova I, Debraekeleer J. Feeding growing kittens:postweaning to adulthood. In: Small Animal Clinical Nutrition 5_^th Ed. Topeka (KA): Mark Morris Institute, 2010; 49-105.