A female dog has eight to 12 teats with 10 being the average for larger breeds. Placed evenly on either side of her chest, teats run down her trunk to her groin where the largest are found. Each teat is part of the underlying mammary gland system.
The mammary glands secrete fluid during and after pregnancy that allows puppies to nurse for approximately 50 days. During nursing, milk glands can become infected or blocked when the skin around the teat is cracked, although bacteria can also enter a teat through the pores. Puppies can continue to nurse if the infection is being treated at home with hot compresses rather than antibiotics.