Calcium is the most abundant mineral in the body. It constitutes 1.5 to 2 % of the total body weight, with more than 99% of the calcium being present in the bones. In addition to its major function in building and maintaining bones and teeth, calcium is also important in the activity of many enzymes. The contraction of muscles, release of neurotransmitters, regulation of heartbeat and clotting of blood are all dependent on calcium. Most dog breeders are unaware of the large quantity of milk produced by lactating female dogs. For example, milk intake of Beagle puppies is about 5.5 ounces per day each. With an average litter of pups, a Beagle female dog will need to produce about one quart of milk per day! Larger breeds will be required to produce substantially more milk each day. For conscientious dog breeders, the challenge is to provide nutrition for the dam that will allow her to not only feed her puppies, but also to maintain her own condition.
When calcium is suddenly needed for lactation, the body's regulatory mechanisms are unable to adapt quickly enough to the sudden calcium loss. If calcium is lost in the milk faster than it is absorbed, or than it can be mobilized from the skeletal system, hypocalcemia results. In dogs, the most common disorder of calcium metabolism is puerperal hypocalcemia. Other names for this condition include postpartum hypocalcemia, periparturient hypocalcemia, and puerperal tetany. A common finding in female dogs producing copious amounts of milk, eclampsia results when heavy lactation depletes the dog's calcium reserve. Although hypocalcemia usually occurs after giving birth, clinical signs can appear before or during the act of giving birth.
Another cause of low blood calcium is malfunction of the parathyroid gland, which produces a parathyroid hormone (PTH) that controls blood calcium levels. In addition, animals poisoned with antifreeze may have a very low blood calcium. Eclampsia is seen at the height of lactation (2-3 weeks after whelping), and occurs more commonly in small- than large-breed dogs. Normally, by 40 days after whelping, the danger of eclampsia has passed. Signs include whining, excessive salivation, restlessness, muscle tremors and rigidity, disorientation, aggression, and, eventually, stiff gait, high fever (>104°F), and convulsions. Some dogs with eclampsia may have not manifest typical clinical signs.
Immediate veterinary treatment is needed for dogs with this life-threatening condition. Therapy consists of intravenous calcium and if needed sodium bicarbonate and glucose. Following initial treatment after the acute crisis, calcium supplements are given for the rest of the lactation. The puppies should be removed from the female dog and hand nursed until weaned. No further treatment should be required for the female dog other than a well balanced diet and close monitoring. Prevention of eclampsia is based on solid nutrition using a diet suitable for the pregnant and lactating female dog. The addition of calcium supplements or diets excessively high in calcium may exert a negative biofeedback on the secretion of hormones by the parathyroid glands that control calcium metabolism. This effect can cause a decrease in both the body's capabilities to mobilize calcium stores from bone and its ability to increase calcium absorption in the intestine.
Lactating Dogs Need Special Foods
The large amounts of healthy milk required by most litters necessitates a very high level of nutrition for a successful nursing process. Many female dogs cannot consume enough calories to ensure adequate milk production and the maintenance of her body condition in one or two meals per day. Total food quantity should be divided into four or more servings per day. Often, the easiest method of providing this large number of calories plus the high digestibility required of the lactating female dog is to offer a "performance" type dog food. Designed for hardworking dogs, these foods have very high energy potential in a dense, highly digestible matrix. The best choice uses fat as the primary energy source. Since fat has over twice the calories per gram as carbohydrates, this allows the nursing mother to get large quantities of energy in a few bites of food.
- Drobatz KJ, Casey KK. Eclampsia in dogs: 31 cases (1995-1998).
- Martin Coffman, DVM. Care and Feeding of the Lactating female dog.