End of Pregnancy
When dogs are nearing the end of pregnancy, their nipples may develop a discharge. The discharge is typically clear or milky in color. The onset time of milk production in dogs varies from one another. Some start developing milk even a week prior, others a day or two prior to giving birth and others right after giving birth.
When a dog gives birth, oxytocin, the primary hormone associated with labor and delivery, is what triggers lactation and the “let-down” of milk, explains Dr. Gen B., a retired veterinarian.
How Do Mammary Glands Develop?
Mammary glands are modified sweat glands that are present in both male and female embryos during fetal development. The nipples remain indistinguishable at birth until sex hormones kick into high gear. The female hormones contribute to the development of mammary glands and their secretory function.
What causes nipple discharge in dogs?
First of all, a lesson in dog anatomy. Consider that all dogs have nipples—male dogs, female dogs, spayed dogs, neutered dogs and, of course, intact dogs. In female dogs, the nipples have an important function; that is, to deliver milk that is produced in the mammary glands so to nourish a batch of hungry puppies.
The mammary glands in dogs are arranged in two rows starting from the chest area all the way up to the groin. While in general, dogs may have anywhere between 8 to 12 glands, with 4 to 6 on each side, large breeds are known for having about 10, while smaller breeds are known for having about 8.
There are no rules written in stone, though, as you may sometimes encounter dogs with extra nipples or dogs with nipples missing. If you want to learn more about where theyre located, consider that large breeds generally have the following:
Each nipple is surrounded by several openings that are meant to allow milk to excrete when the puppy suckles.
You would assume that since male dogs dont have to whelp, Mother Nature would have deprived them of nipples. Instead, just like human men, male dogs have nipples, but they are typically in a rudimentary state. So since the primary purpose of nipples is to excrete milk, its quite normal to be alarmed when you notice a discharge that takes place when dogs arent lactating.
A case of mastitis in sheep.
Causes of Mastitis
The most common cause of mastitis is trauma to the teat, which can allow bacteria to enter the mammary gland. This condition can also occur simply from too much milk in the gland. Nursing dogs are more likely to develop mastitis because of repeated trauma while feeding puppies.