Pregnancy and nursing are not only responsible for many changes in a dog's body, but for changes in her lifestyle as well. If your dog is pregnant or nursing, pay special attention to her changing nutritional needs as she carries, delivers and nurses her puppies.
If you're planning to breed your female dog, it’s important to assess her body condition well in advance of breeding. Because of the physical demands of pregnancy and nursing, a dog with less-than-ideal health can experience problems:
Be sure to feed the proper amounts of a complete and balanced diet. This will support the mother's healthy weight and body condition before breeding and help maintain her health and that of her babies throughout pregnancy and lactation.
The gestation period for dogs is nine weeks. Pregnant dogs gain weight only slightly until about the sixth week, and then gain weight rapidly.
The energy requirements of pregnant dogs are reflected in the pattern of weight gain. Pregnant dogs will need to consume 25% to 50% more than their normal food intake by the end of pregnancy, but energy requirements do not increase until about the sixth week.
The best diet for pregnant and nursing dogs is a high-quality, nutrient-dense pet food formulated for all life stages or for growth. Although puppy diets are generally recommended for pregnant or nursing dogs, large-breed puppy formulas may not be appropriate for this use due to their adjusted energy and mineral content.
Pregnant dogs lose weight after giving birth, but their nutritional needs increase dramatically. Depending on litter size, nursing dogs might need two to three times their normal food requirement to nourish their pups. Be sure your nursing mom has plenty of water so she can generate the milk volume she needs to feed the litter.
To help your nursing dog get enough nutrition, you can try several tactics:

By four to five weeks after birth, most puppies are showing an interest in their mother’s food. Gradually, the puppies will begin eating more solid food and nursing less. At the same time, the nursing mother will usually begin eating less. Most puppies are completely weaned around age 7 to 8 weeks. By this time, the mother's energy requirement is back to normal, and she should be eating her normal pre-pregnancy diet.
Wheat is a grain used as a high-quality carbohydrate source in dry dog foods and biscuits. It provides energy for daily activity, as well as processing characteristics for the food. IAMS™ research has shown that including wheat in a complete and balanced diet results in a moderate glycemic response in dogs, which is lower, in general, than the response observed when a rice-based diet was fed. 1,2
A common misconception is that feeding wheat causes food allergies. The facts are:
Gluten (a protein found in wheat) is responsible for wheat-sensitive enteropathy, occasionally found in Irish Setters from the United Kingdom. Gluten enteropathy of Irish Setters is a malabsorption syndrome, which responds to the removal of wheat (gluten) from the diet. This condition is very rare, and the reason some dogs develop it is not yet clear.
1 Sunvold GD. “The role of novel nutrients in managing obesity.” In: Recent Advances in Canine and Feline Nutrition, Vol II: 1998 IAMS Nutrition Symposium Proceedings. Carey DP, Norton SA, Bolser SM, eds. Wilmington, OH: Orange Frazer Press, 1998; 123–133.
2 Bouchard GF. “Effect of dietary carbohydrate source on posprandial plasma glucose and insulin concentration in cats.” In: Recent Advances in Canine and Feline Nutrition, Vol III: 2000 IAMS Nutrition Symposium Proceedings. Reinhart GA, Carey DP eds. Wilmington, OH: Orange Frazer Press, 2000; 91–101.
3 Jeffers JG. “Responses of dogs with food allergies to a single-ingredient dietary provocation.” J Am Vet Med Assoc. 1996, vol 209(3): 608–611.