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Causes of Nipple Discharge in Dogs

Adrienne is a certified dog trainer and former veterinarian assistant who partners with some of the best veterinarians worldwide.

Nipple discharge in dogs isn't always cause for alarm, but it should never be ignored.

Nipple discharge in dogs isn't always cause for alarm, but it should never be ignored.

If you noticed nipple discharge in your dog, you might be concerned because you may have heard that this can be cancer. While cancer is always a possibility, there are several other causes for nipple discharge in dogs.

You will therefore need to see your vet for proper diagnosis and treatment. This article is only meant to give an idea of what can cause nipple discharge in dogs as only your vet can determine exactly what your dog has.

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?

What causes nipple discharge in dogs?

Understanding Nipples 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 they're located, consider that large breeds generally have the following:

  • 1 pair of cranial thoracic teats
  • 1 pair of caudal thoracic teats
  • 1 pair of cranial abdominal teats
  • 1 pair of caudal abdominal teats
  • 1 pair of inguinal teats

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 don't 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, it's quite normal to be alarmed when you notice a discharge that takes place when dogs aren't lactating.

A case of mastitis in sheep.

A case of mastitis in sheep.

Why Does My Dog Have Nipple Discharge?

Nipple discharge is more commonly seen in intact female dogs, but spayed female dogs and male dogs may also develop conditions that may cause discharge.

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.

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Remember the openings we talked about where milk is secreted for the pups when they suckle? While these openings have an important purpose, one must consider that these same openings may also allow bacteria to enter.

It's a good idea to keep an eye on the mother dog's nipples. It's not uncommon for the mother dog to develop mastitis, the medical term for an infection of the dog's milk-producing glands. It's often caused by the puppy's nails scratching the nipples or unsanitary conditions.

Symptoms include hot, painful mammary glands, and a pus/bloody discharge from nipples. Mother dog may also become reluctant to nurse.

If you suspect your nursing dog has mastitis, see your vet and make sure the puppies don't nurse from the affected nipple as in severe infections the milk can cause serious illness and even death of the puppies. Left untreated, mother dog may develop a fever, loss of appetite, and lethargy.

False Pregnancy

A phenomenon owners of intact female dogs must keep in consideration is what is known as "false pregnancy." After an intact female dog goes into heat, she may develop maternal behaviors such as nesting along with physical signs that are strikingly similar to a real pregnancy.

The physical signs include enlarged mammary gland along with nipple discharge, and in some cases, even abdominal distension. This occurs because after a dog's heat, the dog's body will produce high levels of progesterone regardless if she is pregnant or not.

Generally, signs of false pregnancy develop about a month or two after the dog's heat. Typically, in a dog undergoing false pregnancy, the discharge is seen from multiple nipples at the same, which is quite different from mammary cancer which mostly affects only one.

See your vet to rule out a possible pregnancy or a possible pyometra (infection of the uterus).

An Abscess

In this case, we are talking about an abscess that could have developed as a result of an injury or intrusion of a foreign body. For instance, an abscess may form as a result of a foreign body such as a thorn or small stick that may have introduced bacteria into the skin by the dog's nipple/mammary gland. Then, the puncture closes over, trapping the bacteria inside. This causes local swelling, warmth, and sometimes discharge.

Mammary Gland Cancer

Intact, non-spayed dogs are more commonly affected than spayed dogs as they undergo hormonal changes that rise and fall.

In dogs who were spayed before the first heat cycle, the chances of developing breast cancer are significantly low, just about 0.5%. Chances are also extremely rare in male dogs. However, the statistics grow higher in female dogs spayed after 2 years of age.

When it comes to statistics, 50 percent of dog breast cancer cases are benign, while the remaining 50 percent are not. Non-benign breast cancer in dogs is cancer that has spread to other locations such as the lymph nodes, lungs (causing coughing, labored breathing), or other body parts. Generally, the larger the growth, the bigger the chances that cancer has spread, explains Dr. Daniel A. Degner, a board-certified veterinary surgeon.

Symptoms of breast cancer in dogs include a straw-colored, pus-like, or bloody discharge from the nipple and the presence of small or large nodules within the dog's breast. Mammary tumors are most often seen in the inguinal glands close to the legs. Breast cancer is diagnosed by fine-needle aspiration.

  • Here are some typical findings:
    • Fibroadenoma: A benign glandular tumor
    • Mixed Mammary Tumor: as the name implies, these can be either benign or malignant.
    • Adenocarcinoma: malignant
    • Inflammatory Carcinoma: a highly malignant ulcerated tumor that spreads quickly and produces pus and discomfort, but luckily, not very common

As seen, discharge from the nipples in dogs can be caused by various conditions. Some conditions may be easily treated; others are more serious. See your vet if your dog has fluid coming from her nipples.

Further Reading

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

Questions & Answers

Question: Why does my female Bullpit treat her toy duck like a newborn puppy?

Answer: Is your dog intact? Has she been spayed? If not, then this might be a sign of a false pregnancy.

© 2015 Adrienne Farricelli


Adrienne Farricelli (author) on August 02, 2020:

Sorry to hear about your dog having blood and and puss from her nipples. A vet check would be important here to see what may be going on. Are you sure your dog was pregnant? Was the pregnancy confirmed by a vet? The blood can be sign of an infection or even tumor which is important to rule out.

H on August 01, 2020:

My whitey, shes a cokerpoodle has blood coming from some nipples and puss from others. She has a small lump on one. Other than that shes healthy happy and semi active. Shes 6 yrs old and has had 2 litters. Im worried she may have had a misscarriage

Adrienne Farricelli (author) on July 25, 2020:

Hi Milo,

This can be a sign of false pregnancy. This can occur after a normal heat cycle, even without a male being anywhere near her, but since she is older and it sounds like something you have never seen happen to her before, it's best to be safe than sorry and mention it to the vet.

Milo on July 25, 2020:

My dog who is around 14 or 15 years of age has a clearish-white discharge coming from all her nipples, we don't know if she's had puppies before but we're pretty sure she has and she hasn't been in heat for the three years we've had her.

Samuel on June 03, 2020:

I was looking at me female dogs nipples when I was petting her and some sticky stuff came out of her nipple it wasn’t a lot but I don’t know what it was

Adrienne Farricelli (author) on May 09, 2020:

Lona, please see your vet for this.It could be an injury requiring just plain Neosporin or an infection requiring antibiotics. Another concern is the risk for cancer which you want to have ruled out.

Iona on April 25, 2020:

My dog has a blueish coloured nipple and bloody discharge coming from it but it is only on one nipple two others are completely flat and have a black substance on them and the last two are completely fine and look normal I’m a bit worried since the vets aren’t open,do you know what the problem could be and how to treat it

Adrienne Farricelli (author) on February 06, 2020:

Kami, if the milky discharge is truly milk, this can be due to false pregnancy which tends to develop about a month or two after the dog's heat. This should subside with time. You mention though that your dog hasn't gone recently in heat, so it may be worthy of seeing the vet in case there is something else going on such as a hormonal imbalance. It could also be an infection or abscess and the discharge you are seeing is pus.

Kami on February 05, 2020:

My almost 14 yr old female pit bull is producing a milky substance from only one nipple. And i just took her to the vet less than a month ago for labored breathing, and coughing. Shes only had one litter and that was over 6 yrs ago. She also hasnt been in heat but should be sometime soon now.. i rly cant afford to keep taking her to the vet i just dont have the money for it..but i guess ur gonna tell me to do just that. So i will work on getting some extra money up..

Jackie on January 06, 2020:

Yesterday I noticed my Kona 11 month Shepherd had yellowish-white dry on the tips of her nipples she was in heat about four five weeks ago she acts perfectly normal I keep checking and nothing is wet whatever it's dried on there help please

Adrienne Farricelli (author) on November 30, 2019:

Abbey, please describe what you mean by "milk spots."

Adrienne Farricelli (author) on November 30, 2019:

Hi Tegan,

The purpose of using the term "cancer spread" versus metastasis and non benign versus malignant is to help readers understand since not all people are familiar with such terms.

Abbey on November 27, 2019:

My female pit bull has milk spots like we do correct? If so why would they be black instead of white? Im worried she may be ill in some way tho she acts perfectly fine...

Tegan on November 22, 2019:

You used the word benign to describe cancer that hasn't spread and non benign for cancer that has spread to other organs. The correct term is malignant for a tumor that is cancerous and benign for a tumor that is not cancerous. Metastasis is the process of cancer spreading to secondary organs. Please fact check the information you post.

Adrienne Farricelli (author) on October 03, 2019:

Regina, there is no treatment to stop the milky discharge that is safe as hormones which can be given can cause more problems than anything else. The good news is that the false pregnancy will regress on its own in one to two weeks time.

Regina on September 17, 2019:

How do I treat the milky discharge due to false pregnancy?

Adrienne Farricelli (author) on August 04, 2019:

If you are taking her to the vet ASAP, then you are doing the right thing to remedy the situation. I wouldn't worry. If this is mastitis, with the right type of antibiotics, your dog will heal and all will go back to normal.

Sylvia on July 29, 2019:

My girl has pups 3 weeks ago I bottle fed but now the moms Nipples when I squeeze blood n milk or puss com s out has any one had this I’m thinking of taking to vet ASAP should I wurry

bugga on May 04, 2019:

My dog has had nipple discharge and I'm worried about her health. But the problem is that we also do not have enough money for a vet visit!! Do you have any answers?

Lianna Moch on April 28, 2019:

I was stroking my nearly 13yr old Staffie whilst she was laying on my bed and felt wetness, on inspection it was one of her nipples - it has a slightly rose tint to it, which I assume is blood! There is a small lump also in that area! I fear it could be cancer! Apart from a few health issues she’s otherwise healthy and loves her food and exercise, and is of a good healthy weight!!

Angela on March 03, 2019:

My female boxer has had 3 litters was keeping her inside but there is a chance she is pregnant cuase she got out one night for abt an hr she is very fat full of milk and she has a dark brown puss coming from one of her nipples only out of one hole the other two holes it looks like collostriaum

Joseph on November 04, 2018:

Why is my female pitull producing blood instead of milk??

Grayson Morris on July 19, 2018:

Why is my dog have milk coming out of her breast and she's not pregnant swollen breasts

Priya verma on July 11, 2018:

My 4year lhassa apso have nipple discharge she faced dis problem after 20 days Dr advice surgery to remove uterus she in very pain and don't eat anything from last two days I can't afford surgery please advice me

Michael on May 09, 2018:

My three-year-old Shih Tzu was and he about a month ago a couple weeks later her tits started filling up with milk she’s not pregnant I know what should I do?

Adrienne Farricelli (author) on March 07, 2018:

Erica, I would get that discharge checked out by the vet to play it safe.

Adrienne Farricelli (author) on December 09, 2017:

Naomi, your best bet is to have her see your vet, it can something as innocent as a skin tag to something more serious like a cancer. Too many variables that are not worth the risk of waiting. Best wishes.

Naomi Clemts on December 07, 2017:

Can you please tell me what I can do for my female Chihuahua. She has some kind of a long head coming out of her nipple . She is in no pain she is eating normally and acts like she is fine there is some bruising a round the nipple but the bruising is starting to heal while the head is still in there. Can you tell me what I should do for her I want to take good care of her. Please help me. Thanks ,Naomi

Justin on November 07, 2017:

I’m thinking my dog’s nipple disscharge is from a false pregnancy, but the thing is she hasn’t went into heat just yet. Her next heat should be coming up. I don’t see any signs of blood I’m the discharge.

Jessr on October 20, 2017:

I have a female yorkie,she has yellow crust on all her nipples...Have you heard of this???

Adrienne Farricelli (author) on October 19, 2017:

Can be a sign of false pregnancy or mammary gland infection or tumor.

Jessica on October 07, 2017:

My 11 year old Chihuahua is having discharge from one of her nipples she’s never mated before does this mean she has cancer ?

natasha on August 24, 2017:

my American bulldog has discharge coming from nipples but she aint pregnant wot does this mean

Mike on August 14, 2017:

My pregnant retriever just has a green discharge from her nipple. Is this regular?

Barb on July 15, 2017:

I'm a little worried, my almost 9 year old female unfixed Siberian/Malamute cross, I was petting her belly earlier and noticed what felt like her one breast was feeling full. I know she's not pregnant I'm very careful with her so she don't get pregnant with her age and she don't let the males near her anyway. But I was just checking on her now and it looks like a milky substance is coming out of that nipple. She has been tired a lot lately and a bit moody the last couple days but she seems to be in no pain, even when I put slight pressure on that breast earlier when I first noticed it she didn't squirm away or whimper or anything. Could someone please help explain... I can't afford to take her in to the vet right now.

Adrienne Farricelli (author) on July 09, 2017:

Deborah, it may be a sign of a false pregnancy.

Deborah on July 06, 2017:

My dog. Never been with another dog but she has milk coming out of her breast what do that means

Latrice on June 06, 2017:

I still don't understand why my dog had white stuff come out I am like a kid learning.

What should I do please I do not understand :)

Latonya Aponte on April 30, 2017:

My dog has blood discharge from her nipple for about 2 months she seems to be in no pain.. Eating well still active.. Is she in pain what can I do at home.. no money for vet...

Sthefany on May 31, 2016:

Omg,, thank u so much. I was freaking out that something was wrong with my little girl. Thank god it is just a false pregnancy. ;-)

Devika Primić from Dubrovnik, Croatia on October 09, 2015:

Interesting and most informative. I learned a lot from here on this topic.

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