Female dogs have nipples for the biological purpose of nursing puppies, just like human females have breasts and nipples. While the number of nipples can vary by breed, the average is 8-10 nipples. Dog nipples develop early on, well before sexual maturity, so you may notice them on your young female puppy. Though non-pregnant female dogs still have nipples, they become more pronounced during pregnancy and lactation as the mammary glands prepare for milk production. While it’s normal and expected for intact female dogs to have nipples, you’ll still want to monitor them for any concerning changes. This guide will walk through everything you need to know about your female dog’s nipples.
Anatomy of Dog Nipples
Female dogs have two rows of nipples that run along their abdomen on each side of the midline. The number of nipples can vary by breed, with smaller breeds tending to have fewer nipples compared to larger breeds. Most female dogs have 8 to 10 nipples, though some breeds can have up to 12 (AKC).
A dog’s nipples are made up of a lactiferous duct system and secretory units called alveoli. The lactiferous ducts connect the nipple to the mammary glands, which produce milk during pregnancy and nursing. When a puppy nurses, it stimulates the mammary gland to produce milk, which then moves through the ducts and exits the nipple. The puppy’s suckling causes the release of oxytocin, which stimulates milk letdown. Outside of pregnancy and nursing, the nipples remain small and flat against the abdomen.
While male dogs also have nipples, the mammary glands are not developed like they are in females. Male dog nipples serve no functional purpose. The anatomy of nipples in female dogs enables them to nurse puppies after giving birth.
When Do Female Puppies Develop Nipples?
Female puppies develop nipples while still in the uterus, before they are born. The nipples begin forming around day 35 of gestation and are present at birth. This nipple development occurs regardless of the puppy’s sex, so male and female puppies are born with a set of nipples along their abdomen.
Newborn puppies typically have around 8 to 10 nipples, though the number can vary. At birth, the nipples are small and flat. They will remain in this immature state unless the female puppy goes through puberty and starts cycling. Spaying a puppy before her first heat cycle will prevent the nipples from enlarging or becoming more pronounced.
According to Cuteness, the nipples of male and female puppies are indistinguishable at birth. It is the hormonal changes during the heat cycle that stimulate the mammary glands and cause the nipples to become more noticeable on a female dog.
Why Non-Pregnant Dogs Have Nipples
All female mammals, including dogs, are born with mammary glands and nipples as part of their normal anatomy. The nipples and mammary tissue develop while the dog is still a fetus in the womb. This occurs whether the dog will eventually get pregnant and nurse puppies or not.
Mammary glands and nipples are not just for nursing. They serve an important purpose in the dog’s hormone cycle. The mammary glands have receptors for the hormones estrogen and progesterone. The interaction between these hormones and the mammary tissue causes the nipples to swell and become more prominent at certain times.
According to PetMD, these hormonal cycles happen about every six months in intact (non-spayed) female dogs. The nipples enlarge evenly on both sides of the abdomen. This is sometimes called a “false pregnancy” because the physical changes resemble those of early pregnancy, even without conception occurring.
The nipple development that happens with each hormonal cycle allows the mammary glands to function properly if the dog does become pregnant in the future. So don’t be alarmed if your non-pregnant dog exhibits enlarged nipples. It’s simply a natural part of her anatomy.
Changes During Pregnancy and Nursing
A dog’s nipples go through significant changes when she becomes pregnant and starts producing milk to nurse her puppies. According to Rexipets.com, around the fourth week of pregnancy, increased blood flow to the mammary glands causes the nipples to swell slightly and become pinker in color.
As the pregnancy progresses, the nipples continue to enlarge and protrude more. They also become darker in pigmentation and firm to the touch. This helps the newborn puppies locate the nipples and latch on for nursing. The nipples reach their maximum size right before whelping when they are engorged with milk.
During nursing, the mother dog’s mammary glands produce milk that the puppies extract by suckling. This stimulation causes the milk to be released through ducts behind the nipples. According to Wamiz.co.uk, the mother’s nipples may appear enlarged and discolored from all the suckling activity. They often remain enlarged for a while even after weaning the puppies.
Problems with Dog Nipples
Like any other body part, dog nipples can sometimes develop problems that require medical attention. Two common nipple issues in female dogs are:
Mastitis
Mastitis is inflammation and infection of the mammary glands. It often occurs when bacteria enters the teat canal and spreads to the glands. Mastitis causes the mammary glands to become swollen, firm, and painful [1]. Other symptoms include redness, heat, and discharge from the nipples. Mastitis requires prompt veterinary treatment with antibiotics and anti-inflammatories. Hot compresses can also help soothe inflammation.
Trauma
Injuries to the nipples or teats can allow bacteria to enter and cause infections. Cuts, bites, scratches or other wounds should be cleaned and monitored for signs of infection like swelling, pus, or redness. Veterinary care may be required for serious trauma. Preventing nipple injuries can reduce the risk of mastitis. Signs of nipple trauma include bleeding, scabs, and sensitivity [2].
With prompt care and treatment, most nipple problems can be resolved. Pet owners should monitor their dog’s nipples and contact their veterinarian if any abnormalities develop.
Caring for Your Dog’s Nipples
Keeping your dog’s nipples clean and preventing injury are important parts of nipple care. Here are some tips for caring for your dog’s nipples:
Gently wipe your dog’s nipples with a warm, damp cloth 1-2 times per day to keep them clean. Avoid using harsh soaps, chemicals, or scrubbing, which can cause irritation (Source).
Inspect your dog’s nipples daily for any signs of injury, redness, sensitivity, or infection. Contact your veterinarian if you notice any changes or concerns.
Trim the fur around the nipples if needed to prevent matting or trapping dirt. Be very careful not to nick the skin when trimming.
Apply a small amount of purified lanolin cream to soothe and protect sore, cracked nipples. Check with your vet first (Source).
Prevent your dog from traumatizing her nipples by removing collars, dangling tags, rough play, or jumping during nursing. Provide a soft whelping area.
Allow nursing puppies to feed freely to keep the milk flowing well. If engorgement occurs, cold compresses, gentle massage, or your vet’s advice may help.
When to See the Vet
If you notice any abnormalities with your female dog’s nipples, it’s important to have her examined by a veterinarian. Here are some of the signs that indicate a need for veterinary care:
Signs of infection or inflammation include redness, swelling, pain, and heat coming from the nipple or mammary gland. Your dog may act lethargic and show signs of illness. Infection of the mammary glands is known as mastitis and requires prompt veterinary treatment with antibiotics and possibly draining of abscesses [1]. Left untreated, mastitis can lead to sepsis.
Abnormal nipple discharge in a non-nursing dog can indicate a health problem. Any bloody, pus-like, or unusual discharge should be evaluated by your vet, as it could signal an infection, tumor, or other issue [2]. Benign conditions like galactostasis may also cause discharge.
Swollen or enlarged nipples can sometimes indicate breast cancer, cysts, or other mammary gland tumors [3]. Your vet will examine your dog and may recommend tests like mammograms, ultrasounds, biopsies, or bloodwork.
It’s always better to have your vet evaluate any nipple changes early. Prompt treatment will give your dog the best chance at recovery.
Spaying and Nipple Development
Getting your female dog spayed (ovariohysterectomy) before her first heat cycle prevents enlarged nipples from developing. According to PetMD, spaying a dog removes her ovaries and uterus, eliminating heat cycles and preventing pregnancy. Without fluctuating reproductive hormones, the mammary glands do not enlarge and nipples stay small.
However, if a dog is spayed after maturity, the nipples have already enlarged from hormonal changes. Even without ovaries, residual hormones can still circulate and cause mammary changes like swelling. According to veterinarians, spaying prevents false pregnancy, but does not reverse enlarged nipples already present. While swelling often diminishes after spaying, some residual nipple enlargement may persist.
Summary
All female dogs have nipples, even if they are not pregnant or nursing puppies. Nipples start developing when female puppies are embryos and become more prominent around puberty. While the number of nipples can vary, this is completely normal. Male dogs also have nipples, which serve no reproductive purpose but are retained as an embryonic remnant from before sex differentiation. It’s important to monitor your dog’s nipples regularly for signs of problems like infection, trauma, or cancer. Swelling, discharge, redness, lumps, and pain can indicate an underlying condition needing veterinary attention. With proper care and awareness, most nipple issues can be treated successfully. In summary, dog nipples are a normal part of anatomy, but their appearance and health offers important insight into your dog’s overall wellbeing.
