One concerning symptom for dog owners is when their dog’s nipples become red and swollen. This abnormal appearance of the nipples often raises alarm and dog owners want to quickly determine the cause. Red and swollen nipples in dogs can indicate an underlying medical issue that requires veterinary attention. It’s important for dog owners to monitor their dog’s nipples and understand what is normal versus abnormal. This article will summarize the common causes of red and swollen dog nipples, when to see the vet, and steps owners can take to prevent nipple issues.
Normal Nipple Appearance
Normal healthy dog nipples are small, pink, and flat. They usually blend in with the surrounding skin and fur. The number of nipples can vary, but female dogs typically have 8-10 nipples, while males have 4-6. When a female dog is not pregnant or nursing, her nipples will appear small, round, and flattened against her belly.
According to one source, “Once your dog has nursed puppies, her nipples will be more prominent, longer, and darker. When a mammal is pregnant, their nipple color darkens…” (https://a-z-animals.com/blog/normal-dog-nipple-appearance-vs-pregnant/).
Here is an example of what normal healthy dog nipples look like:
As you can see, they are small, flat, and blend in with the surrounding fur and skin color. This is considered the normal appearance for non-pregnant, non-nursing female dogs as well as male dogs.
Common Causes
There are several common causes of red, swollen nipples in dogs:
False Pregnancy
One of the most frequent reasons for nipple swelling in female dogs is a false pregnancy. This occurs after a heat cycle when elevated progesterone levels cause physical and behavioral changes that mimic pregnancy even though no mating occurred. The dog’s nipples may enlarge and become red and swollen just like they would if she was actually pregnant. This usually resolves on its own within 2-3 weeks.
Mastitis
Mastitis refers to inflammation and infection of the mammary glands. It is most common in female dogs who are nursing puppies, but can also occur in dogs who aren’t pregnant or lactating. The skin around the nipple becomes red, painful, and swollen, and there may be discharge coming from the nipple. Mastitis is usually caused by a bacterial infection that enters through cracks or trauma to the nipple skin. It requires antibiotic treatment and warm compresses to resolve [1].
Trauma
Injuries from scratches, bites, cuts, or blunt trauma can cause swelling and bruising of the nipples. This type of trauma often leads to infection as bacteria are introduced into the delicate nipple tissue. Careful cleaning and antibiotics are necessary to treat nipple trauma.
Mammary Tumors
Though not as common as other causes, mammary gland tumors can also lead to swelling, redness, and pain of the nipple area. These may feel like a firm lump underneath or around the nipple. Mammary tumors tend to occur in older, unspayed female dogs. Seeking prompt veterinary care is important for diagnosis and treatment.
False Pregnancy
A false pregnancy, also known as pseudopregnancy or phantom pregnancy, occurs when a female dog shows signs of pregnancy even though she is not actually carrying puppies. This happens because her hormones mimic the cycle of pregnancy and birth without an actual conception taking place.
The hormonal changes that occur during a false pregnancy are the same as those of a normal pregnancy. Following the heat cycle, progesterone levels remain elevated which signals the body to prepare for pregnancy and nursing. Even though no puppies have been conceived, the dog’s body doesn’t realize this and begins producing milk and enlarging mammary glands in preparation for nursing. Hormone levels eventually drop off causing the mammary glands to swell as they fill with milk, which is a normal part of the pregnancy cycle. However, since no puppies will suckle and relieve pressure in the mammary glands, they become engorged and swollen.
Common symptoms of a false pregnancy include:
- Enlarged, swollen, or reddened nipples
- Mammary glands producing milk
- Lethargy or depression
- Decreased appetite
- Nesting behaviors like digging or collecting toys
- Mothering behaviors like carrying toys around as if they were puppies
A false pregnancy typically lasts 2-3 weeks from start to finish. Most symptoms subside on their own without treatment, though gently expressing excess milk from the mammary glands can provide relief. Unspayed dogs may have recurring pseudo-pregnancies with each heat cycle.
To treat or prevent false pregnancies, veterinarians may recommend spaying to stop the hormonal fluctuations of the heat cycle. They may also prescribe hormones or other medications to correct the imbalance triggering pseudopregnancy symptoms.
Mastitis
Mastitis is an inflammation of the mammary glands caused by a bacterial infection (VCA) . It most commonly occurs in female dogs who are in the nursing stage or who were recently nursing puppies. The mammary glands can become engorged with milk, allowing bacteria to thrive and causing infection. Bacterial mastitis can affect one or multiple nipples/mammary glands. Risk factors include trauma to the nipples, lack of nursing by puppies leading to milk stasis, and immune system issues.
Symptoms of mastitis include hot, painful, swollen nipples and mammary glands, and abnormal discharge. The areas may appear red or bruised. Dogs may act lethargic, lose their appetite, run a fever, and be reluctant to nurse. Diagnosis is made through physical exam, palpation, and bacterial culture. Treatment involves antibiotic therapy, anti-inflammatories for pain and swelling, warm compresses, and gentle massage to promote milk drainage. In severe cases, the infected mammary tissue may need surgical removal. Prompt veterinary care is crucial so that the infection does not spread. With appropriate treatment, the prognosis for recovery is good (The Spruce Pets).
Trauma
Nipple or teat injuries are one of the most common causes of mastitis in mother dogs nursing puppies. The trauma allows bacteria to enter the teat canal and infect the mammary gland. Puppies may inadvertently damage their mother’s nipples while nursing due to their sharp teeth. The trauma can lead to cracked nipples, puncture wounds, scratches, or other injuries that compromise the integrity of the skin.
Other sources of trauma include sharp toys, sticks or branches in the environment, scratches from other animals, wounds from grooming tools, etc. Even minor injuries are enough to allow bacteria inside the teat. Signs of a nipple injury include swelling, redness, pain, oozing, and the mother dog crying out when the puppy nurses from that nipple.
Treatment involves keeping the wound clean to prevent infection. Veterinarians may prescribe antibiotics and recommend warm compresses on the nipple. Prevention involves monitoring nursing sessions closely and using gentle restraint on puppies to control biting. Filing down puppy teeth regularly can reduce damage. Providing safe toys and clearing sharp objects from the environment also helps prevent nipple injuries.
Sources:
https://vcahospitals.com/know-your-pet/mastitis-in-dogs
https://www.thesprucepets.com/mastitis-in-dogs-4846628
Mammary Tumors
Mammary tumors or mammary gland tumors are abnormal growths in a female dog’s mammary glands. Approximately 50% of mammary tumors in dogs are malignant or cancerous [1].
There are several types of canine mammary tumors. Adenomas are benign while adenocarcinomas are malignant. Other types include fibrosarcomas, osteosarcomas, and inflammatory mammary cancer. Mixed mammary tumors contain both benign and malignant cells.
Risk factors for mammary tumors include older age, intact female dogs, and breeds like Poodles, Spaniels, Boxers and Brittany Spaniels. Obese female dogs also have a higher risk.
Symptoms include single or multiple palpable masses or swellings in the mammary gland area. Nipple discharge may also occur. Mammary tumors can often be detected via palpation during annual exams.
Diagnosis involves a physical exam, fine needle aspirate or biopsy. Staging tests like bloodwork, imaging and lymph node samples help determine if the cancer has spread. Treatment includes surgery, chemotherapy, radiation and anti-estrogen therapy.
Early detection and treatment is key to better prognosis. Spaying dogs before their first heat cycle greatly reduces the risk of mammary tumors.
Other Causes
While false pregnancy, mastitis, and trauma are the main reasons for nipple swelling in dogs, there are some less common causes as well:
- Insect bites or stings – Bites from fleas, mosquitoes, or other insects can cause irritation and swelling of the nipples.
- Allergic reactions – Dogs can have allergic reactions to foods, medications, shampoos, or other substances that lead to skin inflammation and nipple swelling.
- Dermatitis – Skin conditions like contact dermatitis can spread to the nipples.
- Abscesses – Bacterial infections of the skin or mammary glands can form abscesses that affect the nipples.
- Medication side effects – Some medications like corticosteroids may cause swelling as a side effect.
If the nipple swelling seems unusual or persists for more than a few days, it’s a good idea to see the veterinarian to identify the underlying cause and provide appropriate treatment. Mild cases often resolve on their own, but medications may help reduce swelling and discomfort.
When to See the Vet
It’s important to have your dog’s swollen or discolored nipple examined by a veterinarian to determine the underlying cause and appropriate treatment.
You should make a veterinary appointment right away if the nipple is red, inflamed, hot, or oozing fluid. These signs indicate infection or inflammation that requires medical care.
Also see the vet promptly if the nipple is ulcerated, bleeding, or has an abnormal growth or lump. These may be signs of a mammary tumor that needs diagnostic testing.
Even if your dog is not spayed and the nipple swelling seems related to a false pregnancy, it’s a good idea to have her evaluated to rule out other issues.
Monitoring changes in your dog’s nipples at home is important, but a veterinarian can perform an exam, run tests, and prescribe any necessary medications to properly diagnose and treat the condition.
According to the VCA Animal Hospitals, you should seek veterinary care for any abnormal nipple swelling, discharge, pain, or change in appearance in your female dog.
Prevention
There are some steps dog owners can take to help prevent nipple injuries and problems:
- Spay your dog if she is not intended for breeding. Spaying removes the hormones that cause false pregnancies and mammary tumors. [1]
- Make sure nursing puppies latch on properly when feeding. Improper latching can cause nipple trauma. Gently readjust the puppy’s mouth if needed.
- Keep nursing areas clean to prevent mastitis infections. Gently clean nipples with warm water and avoid using harsh soaps.
- Prevent excess chewing and licking of nipples. Use an Elizabethan collar if necessary.
- Limit rough play and pestering from other pets. This can irritate nipples.
- Trim nails regularly to prevent scratches.
- Visually inspect nipples daily for any changes. Look for swelling, reddening, discharge or sores. Contact your vet if you observe any abnormalities.
Staying alert to nipple health and taking preventative measures can help avoid many common nipple problems in dogs.
