Lactation in Dogs

Hormones that Contribute to Lactation

• Lactation simply would not occur without four hormones. Estrogen is the first hormone that comes into play because it is produced in the ovaries and is responsible for communicating to the mammary glands that pregnancy has occurred.

  Progesterone is another hormone that is secreted by the body of the mother, as it helps to activate and keep active the mammary secretions during lactation. Progesterone does not stimulate milk production until the effects of the estrogen are made known, so if there is a problem with estrogen production the progesterone will not respond accordingly, either.

  Prolactin is an important hormone in the body of the mother because it is secreted to prepare the mammary glands for milk production and will continue this process throughout lactation. This is also the hormone that is responsible for inspiring maternal behavior in a female dog.

  Relaxin is also involved in lactation in dogs. It is only found in the system during pregnancy and throughout lactation and is responsible for helping in mammary development. Relaxin is often used to diagnose pregnancy through blood work.

When Lactation Begins

• During pregnancy the four hormones mentioned previously are working to develop and prepare the mammary system for lactation but the milk production does not actually begin until labor begins. The pressure of the puppies against the cervix of the mother stimulates the body to release prolactin, which will begin milk production.

Nutrients Available to Puppies Through Milk

• The milk produced by the mother changes with the needs of the puppies. In the first few days the body will product colostrum, which is high in immunoglobulins and helps to develop the immune systems of the puppies. The milk that is produced by the mother will be able to sustain the puppies for the first four weeks of life, at which point they will begin to eat puppy food and gradually wean off of the milk by six to eight weeks of age. The protein increases over time from 4.5 percent to 6.5 percent by the sixth week. In addition, the fat content of the milk will increase from just 2.5 percent to 4.5 percent in the first three weeks.

Lack of Milk Production

• Lack of milk production is not uncommon after the puppies are six weeks of age. This is generally due to diminished frequency of suckling by the puppies. Lack of milk production is called agalactia and this can be caused by many things. If the puppies are delivered via cesarean section, milk production may be slow since labor did not occur and the prolactin was not released. Lack of milk production can also be caused by high temperatures in the nesting area, not enough food and water, or even infection. Medical intervention may be necessary.

Mastitis in Lactating Dogs

• Mastitis is relatively common in lactating dogs. This is an infection of the mammary gland and can affect one or all glands. The milk may or may not be safe for the puppies to drink, so this is something that should be avoided if at all possible. Mastitis is caused by bacterial contamination of the teats with symptoms being redness, unusual swelling, and discomfort or even pain during nursing. Symptoms should be treated immediately by a veterinarian to limit the extent of the infection.