Dogs Have Nipples for Breastfeeding Their Puppies
Female dogs have nipples in order to breastfeed their puppies after giving birth. The mammary glands located under the skin produce milk that the puppies drink for nourishment. According to the Cornell University College of Veterinary Medicine, puppies will nurse from their mother until they are about 10 weeks old [1].
Nipples develop on all puppies in the womb before sex differentiation occurs, according to the City of Austin Animal Services. Therefore, male dogs have nipples since all puppies originally develop as females. The hormones that control sex differentiation don’t kick in until a few weeks after conception. So nipples form on all puppy fetuses, even those genetically male [2].
[1] https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/health-info/how-long-should-puppies-stay-their-mother
[2] https://www.austintexas.gov/sites/default/files/files/Animal_Services/Foster_Care_Manual/Nursing_Mother_Dogs_and_Their_Puppies.pdf
Nipples Develop Before Sex Differentiation
In mammals, nipples develop in utero before sex differentiation occurs [1]. During the early stages of fetal development, mammary ridges or “milk lines” form on the torso area of both male and female fetuses. The mammary ridges eventually regress except for a few areas that become mature nipples and mammary glands.
Therefore, since nipples develop before the fetal sex organs differentiate into male and female, both male and female mammalian fetuses develop nipples. This early nipple development explains why male mammals like dogs have nipples – they formed nipples in the womb before their sex was determined [2].
Male Dogs Have Nipples Since They Developed as Fetuses
Since nipples develop before sex differentiation, male and female puppies are born with nipples. In the early stages of fetal development, all embryos have the same primitive structures that develop into nipples. It’s not until several weeks into pregnancy that the sex organs develop and hormones determine if the fetus will become male or female. But by this point, the nipples have already formed.
Male dogs retain their nipples into adulthood even though they have no function. Unlike female dogs who require their nipples for nursing puppies, the nipples on a male dog are non-functional left over from their time in the womb. While they serve no purpose, the nipples do not pose any medical problems for male dogs either. They can simply be considered a vestigial remnant of embryonic development.
Male dogs typically have 4 to 6 pairs of nipples, though the number can vary. The nipples are located along two milk lines that run from the groin area up to the torso on both sides of the belly. Even neutered male dogs retain these nipples throughout their lives. So the sight of nipples on a male dog is perfectly normal and no cause for concern.
Spaying/Neutering Prevents Pregnancy
Spaying female dogs and cats can prevent uterine infection and greatly reduce the risk of mammary (breast) cancer, as removing the ovaries eliminates estrogen production which can fuel tumor growth (https://www.avma.org/resources-tools/pet-owners/petcare/spaying-and-neutering). Neutering male dogs eliminates the risk of testicular cancer and prevents unwanted sexual behaviors.
Most importantly, spaying females and neutering males prevents dogs from becoming pregnant or impregnating other dogs. Intact female dogs go into heat and produce hormones that attract males. Intact male dogs are driven to seek out females in heat to mate with. However, when dogs are spayed or neutered, their hormone levels are significantly reduced, eliminating mating urges or pregnancy capabilities.
Therefore, spayed or neutered dogs may retain nipples from before the surgery, but they can no longer experience pregnancy after the procedure. The presence of nipples does not mean a dog was ever pregnant, especially for adopted dogs with unknown histories. As long as your dog is spayed or neutered, you do not need to worry about surprise pregnancies.
Pseudopregnancy Can Cause False Pregnancy Signs
Female dogs can experience a false pregnancy called pseudopregnancy, when hormonal changes lead to pregnancy-like symptoms without an actual pregnancy occurring. Pseudopregnancy most often happens 2 to 3 months after the female dog goes into heat. The exact cause is unknown, but it’s thought to result from hormonal fluctuations after ovulation. Some signs of pseudopregnancy include:
- Abdominal enlargement
- Mammary gland enlargement and milk production
- Mothering behaviors like nesting and mothering toys or other objects
- Decreased appetite or vomiting
- Lethargy and depression
- Aggression or other behavioral changes
Pseudopregnancy symptoms typically resolve on their own within 2-3 weeks as hormone levels return to normal. However, symptoms like lethargy and vomiting can indicate more serious conditions, so veterinary care is recommended if these develop (Source).
Mammary Gland Cancer Risk in Dogs
Female dogs have a significant risk of developing mammary tumors and breast cancer. Studies show that female dogs left intact have a risk of developing mammary tumors of around 25% if spayed after one heat cycle, 8% after two heat cycles, and just 0.5% if spayed before their first heat cycle [1]. The longer a female dog goes unspayed, the higher her risk becomes.
The reason for this is that mammary gland tumors are hormone-dependent cancers. The ovaries produce estrogen, progesterone and other hormones that stimulate cell growth in the mammary glands. When a female dog is spayed and has her ovaries removed, these hormonal influences on the mammary tissue are eliminated, greatly reducing the risk of mammary cancer [2].
Therefore, veterinarians strongly recommend spaying female dogs before their first heat cycle, which usually occurs around 6-10 months of age. Spaying at this early age provides the maximum protection against mammary cancer later in life [3]. While spaying at any age reduces risk somewhat, the preventative benefits are greatest if done before the first heat cycle begins.
Puppy Formula Can Supplement or Replace Nursing
Orphaned or rejected puppies can be hand-raised with commercial puppy formula. Formula provides complete nutrition if the mother cannot nurse. According to VCA Animal Hospitals, orphaned puppies should be fed every 2-4 hours on a strict schedule for adequate nutrition and development (https://vcahospitals.com/know-your-pet/feeding-orphaned-puppies). The general rule is to feed puppies every 2-3 hours in the first weeks. Hand feeding can be phased out starting in the 3rd-4th week as the puppies transition to moistened solid food.
Brands like PetAg Milk Replacer Plus for Puppies, Esbilac Puppy Milk Replacer Powder, and Royal Canin Babydog Milk are specially formulated to provide complete nutrition for orphaned puppies. According to Best Friends Animal Society, formula should contain 22-30% protein and 10-15% fat for proper growth (https://resources.bestfriends.org/article/caring-orphaned-newborn-puppies-feeding-socializing-and-more). Care should be taken not to overfeed puppies to avoid digestive issues.
While challenging, hand-raising orphaned puppies can be done successfully with dedication to their frequent feeding and care. High quality commercial formula provides the nutrients they need to thrive when nursing from their mother is not possible.
Adopting Dogs with Unknown Histories
Many adopted dogs come from unknown backgrounds, so pregnancy history is uncertain. Shelters and rescue organizations often don’t have information about a dog’s history before arriving at the shelter. Stray dogs may have lived on the streets for some time before being brought to a shelter. Even owner surrenders often lack thorough medical records.
Without knowledge of a dog’s history, it’s impossible to know for certain if female dogs have had a litter before. Physical signs are not definitive indicators of past pregnancy. Some female dogs develop enlarged nipples or stretched abdominal skin without ever being pregnant. The only way to know a dog’s pregnancy history for certain is through medical records from a previous owner.
Since most adopted dogs lack this verified background, veterinarians recommend health screening when adopting a new dog with an unknown history. Screening tests like bloodwork, urinalysis, skin scrapings, and fecal tests can identify medical conditions a dog may have. These tests establish a health baseline to monitor going forward. Preventive care plans also help keep adopted dogs healthy. With regular veterinary care, adopted dogs can live long, fulfilling lives in their new forever homes. https://www.aaha.org/publications/newstat/articles/2018-12/preventive-care-screening-tests-why-now/
Consider Dog’s Entire Health, Not Just Pregnancy
When caring for your dog, it’s important to consider their entire health history and veterinary needs, not making assumptions based only on physical traits like nipples. An annual veterinary wellness exam allows for a thorough review of your dog’s health and the creation of an individualized care plan.
According to the AAHA-AVMA Canine Preventive Healthcare Guidelines, every dog should have a veterinary exam at least once per year. This wellness visit includes a physical exam, review of vaccination status, laboratory tests, and discussion of preventative care recommendations. Your veterinarian will evaluate your dog’s current health status and risk factors to determine an appropriate plan for wellness, disease screening, and treatment.
Components of the wellness exam may include (source):
- Complete blood count
- Biochemistry profile
- Thyroid testing
- Urinalysis
- Fecal examination
- Heartworm test
- Dental examination
- Dermatological evaluation
Don’t assume your dog’s health status based only on physical traits. Work with your vet for appropriate wellness care, preventative medicine, and prompt treatment when needed. This comprehensive approach is the best way to support your dog’s overall wellbeing.
Love Your Dog Unconditionally
One of the most special aspects of our relationship with dogs is the unconditional love and loyalty they show us. Unlike humans, dogs don’t judge based on superficial qualities – they love us fully for who we are on the inside. While we may fixate on physical details or imperfections, our dogs offer complete acceptance.
When it comes to something like your dog having nipples, it’s important not to let that impact how you feel about them. Male or female, nipples or no nipples, votre chien est parfait! Dogs don’t care about our “flaws” so we should extend them the same loving treatment. Nurture your bond by loving your dog wholeheartedly, just as they love you.
By embracing your dog unconditionally, you allow the profound human-animal connection to deepen. Studies show pet owners experience reduced stress, loneliness, depression and anxiety thanks to the unconditional support dogs provide [1]. Cherish your faithful companion by loving them for exactly who they are.
