The Puppy's Changing Digestive Ability
Many gradual changes occur as the puppy develops and its ability to digest foods changes. To cite only one example, the number of lactose-digesting enzymes gradually decreases, while the ability to digest cooked starch increases much more slowly. These variations explain why some puppies cannot tolerate cow's milk (which is three times richer in lactose than bitch milk), and why it is sometimes sufficient to limit the amount of cow's milk fed to stop diarrhea caused by exceeding the digestive ability of the lactases.
These changes are essentially genetically determined and depend very little on the eating habits imposed on the puppies.
Nutrition During Weaning
The beginning of weaning is naturally imposed when milk production by the bitch levels off. It is as thought the mother, having reached maximum production, gives up and admits that she can no longer satisfy the increasing needs of her puppies.
In small-breed bitches, lactation covers the most intense growth period of the puppies, and meets their greatest needs. In medium-and large-breed dogs, however, the puppies are "abandoned" by the mother's milk at a critical period in their growth. So, while gestation and lactation are more taxing in small-breed bitches than in large-breed bitches, the opposite is true for the puppies.
No matter how the puppies get their milk, weaning should be a gradual change of diet beginning at about three weeks of age and ending at seven or eight weeks, at which time the mother will begin to distance herself from the puppies, mainly by asserting her precedence at the dog dish.
The puppies should not be completely separated from their mother before this time, so as to avoid adding any stress to a period that is already sensitive to any drastic change in routine.
As an example, the puppies could be separated from their mother during the day, and reunited with her at night.
While the puppies are being weaned, their nutritional requirements are qualitatively comparable to those of their mother at the end of lactation (i.e., during the period when she is rebuilding her reserves), which makes the owner's job considerably easier.
If no weaning formula is available, the owner can put out a little puppy kibble (growth formula) mixed with warm water or puppy formula. Gradually, less and less water will be added to this food, so that at the end of weaning it is given dry.
It should be emphasized here that the use of homemade food always requires correction of mineral levels in the base food by addition of a commercial supplement, ground eggshell, or bone meal; otherwise, mineralization of the skeleton might be hindered. The daily readjustment required with such supplementation makes the practice rare this days.
In contrast, the addition of a mineral supplement to an already-balanced (commercial) base food may lead to early and irreversible calcification, even in large breeds, thus seriously compromising the growth and the futures of puppies.
Calcium requirement are calculated as a function of the puppy's weight, ranging from 400 mg/kg at the beginning of growth to 200 mg/kg, the estimated need of the adult, at the end of growth.
As an example, a growing puppy that weighs 30 kg will require six times more calcium than a 5-kg puppy at the same stage of development. However, its energy requirement will be only four times greater. This is why it is important to feed each puppy a food having a calcium/energy ratio adapted to its growth potential.
Feeding the litter dry food that is always available avoids any competition for food among the puppies, and so also any diarrhea related to overeating. When weaning, it is recommended that the puppies be fed three or four meals a day for a limited time (15 minutes) to avoid obesity.
After weaning, two meals per day are adequate for most puppies.
Any obesity appearing when fat cells are multiplying at full speed (know as hyperplastic obesity) would be much more difficult to treat than excess fat acquired in adulthood (hypertrophic obesity).
During the growth period, any nutritional imbalance affects the tissues that are forming.
So small-breed puppies, weaned right in the middle of adipose tissues formation, are predisposed to obesity if they overeat. For this reason, slight under-feeding is less harmful in these dogs than overfeeding, since slightly retarded weight gain can be compensated for afterwards, while obesity arising during the growth period is difficult to reverse once the dog reaches adulthood.
In large-breed puppies, on the other hand, weaning takes place during the period of skeletal growth. Any dietary deficiency of proteins or calcium will affect the formation of the bones (osteofibrosis). In contrast, consumption of excess energy accelerates growth, which makes the puppy vulnerable to many problems such as hypertrophic osteodystrophy and joint dysplasias.