The greater the size of the adult dog, the more limited the proportional weight of the puppy. A newborn Yorkshire terrier (3 to 4 ounces) is 5% of the weight of the dam. In comparison, a Great Dane weighs only about 1 ½ lbs at birth, which is around 1% of the weight of its mother.
Large breed dogs will weigh between 55 and 100 pounds at adult status, while giant breeds will weigh over 100 pounds.
The puppy's weight increases very rapidly. It doubles within seven to ten days, triples within three weeks and is four or five times its birth weight after a month.
A giant breed puppy is half its adult weight by five months. It continues to put on weight until the age of 18 to 24 months, by which time it has multiplied its weight by a factor of 80 to 100 (compared with 20 to 30 for a small breed dog). This means that its growth is a particularly delicate phase, subject to many nutritional errors.
There are two distinct phases in the growth of puppies, which are especially important in large and giant breed puppies. The first phase occurs from birth to approximately four or five months of age, depending on anticipated adult size. This growth phase is exponentially fast, during which the main part of the skeleton is developed. The rate of growth peaks between three and five months in large and giant breed pups. During this peak, a large breed pup can regularly gain five to seven ounces a day, which is more than two pounds a week. The larger the dog, the later the growth peak and the longer the growth phase. A Great Dane pup will typically reach 50% of its adult weight by month five.
The second growth phase is much slower, and when muscles develop, continuing until adult weight has been reached. A large or giant breed puppy will reach 80% of its adult weight around the age of eight months, at which time the growth rate slows very noticeably.
The energy requirement of a puppy is much greater than that of an adult, because the energy requirement for growth and maintenance are added together. . In the early months of growth phase one, the total energy need is at least double that of an adult dog. As growth advances, the factor gradually falls. At five months of age, when a large or giant breed pup reaches 50% of adult weight, the energy requirement is 1.75 times that of the adult dog. At eight months (80% of adult weight), the energy requirement of the same large or giant breed puppy is only 1.3 times that of the adult dog.
It is important to adapt the energy level of the puppy food to the growth phase. In phase one, when the growth rate is at its most rapid, and energy needs are easily twice that of an adult dog, an energy dense food that is balanced for all nutrients according to the kilocalorie (kcal) content is the best choice. Puppies have limited digestive capacity, and insufficient digestive enzymes, requiring a food that has optimal digestibility in a limited ration volume. This prevents the puppy from having to consume a large volume of food in order to take in the required nutrients appropriate for its age. Growth needs to be monitored by weekly or more frequent weighing. The puppy must not exceed 50% of its estimated adult weight at the age of 5 months. If it does, the ration will have to be reduced.
Growth slows down from month five, the energy requirement falls and the digestive tract is ready to receive a larger quantity of food. The risk of over-consumption is greater, though, as the puppy's appetite grows. This second growth phase is the time to offer food that is physically less dense and lower in energy, to avoid the need to ration the puppy too strictly. Several studies have shown a significant correlation between over-consumption of energy by large or giant breed puppies and the higher incidence of joint complaints observed in radiographs (hip dysplasia, osteochondritis etc). The rhythm of growth is directly influenced by the energy supply. Surplus energy consumed accelerates the attainment of adult weight. The resulting overload on still immature joints increases the risk of joint damage. Large and giant breed puppies are more susceptible to premature osteoarthritis than other breeds. Their larger weight imposes mechanical constraints on their joints. These puppies often have a very active lifestyle and dysplasia of the hip or the elbow can be stimulated by certain genetic predispositions.
Generally, while exercise is essential to develop young puppies' muscles, it is necessary to be prudent with large breed puppies. Do not allow them to jump about and do not subject them to endurance exercise before the bones have stopped growing.