Mastitis in Dogs: Symptoms and Treatment

Mastitis in dogs is inflammation of the mammary glands in female dogs and can occur with or without infection. It typically occurs postpartum and can range from mild inflammation to severe disease.

Treatment depends on the type and severity of mastitis and may include antibiotics, supportive care, topical therapy, or surgery.

What Is Mastitis in Dogs?

Mastitis in dogs is inflammation of the mammary glands in female dogs. It can occur with or without infection.

Mastitis typically occurs postpartum due to how messy the whelping box can become and/or weaning puppies abruptly or too early. There are multiple types of mastitis in dogs.

Acute Mastitis

Acute mastitis causes sudden swelling of the mammary gland, along with heat and pain. The milk will be obviously abnormal. This type of mastitis may also cause changes in the mother, such as lethargy.

Septic Mastitis

Septic mastitis causes sudden swelling of the mammary gland associated with heat, pain, abnormal milk coloration, and changes in the mother, such as lethargy, changes in appetite, and fever.

Septic mastitis and its symptoms are typically caused by bacteria.

Chronic or Subclinical Mastitis

Chronic or subclinical mastitis is long-term inflammation of mammary tissue accompanied by a lack of obvious clinical signs, such as swelling or warmth.

Non-Septic Mastitis

Non-septic mastitis is inflammation of the mammary tissues without a cause such as bacteria or fungus.

Gangrenous Mastitis

With gangrenous mastitis, the teat and possibly the surrounding tissues appear black or bruised. The milk may be blood-tinged or bloody.

The mother will also be very ill, with symptoms such as vomiting, decreased appetite, fever, and changes in blood pressure.

What Are the Symptoms of Mastitis in Dogs?

Symptoms of mastitis in dogs vary depending on the type of mastitis. Affected mammary glands may be swollen, warm, firm, discolored, painful, or ulcerated (skin broken open), while milk or fluid from the glands may appear discolored, bloody, or pus-like.

Acute and Septic Mastitis Symptoms

Acute mastitis may cause mammary glands to become hot and painful. This condition may progress to septic mastitis if it's not treated in time.

Signs of septic mastitis may include:

• Fever
• Depression
• Anorexia
• Lethargy
• The mother neglecting her puppies

Chronic or Subclinical Mastitis Symptoms

The only clinical sign observed with chronic or subclinical mastitis is failure of the puppies to thrive.

Non-Septic Mastitis Symptoms

Non-septic mastitis commonly occurs at weaning, about three to four weeks after birth. Common signs include swollen glands that are painful to touch, even though the dog is relatively healthy and alert.

Symptoms of Severe Mastitis

In severe cases of mastitis, the mother may be sick and show symptoms such as:

• Fever
• Refusal to eat
• Vomiting
• Listlessness
• Rapid heart rate
• Depression
• Severe drop in blood pressure

What Causes Mastitis in Dogs?

Mastitis in dogs is most commonly caused by bacteria, such as E. coli, enterococci, staphylococcus, and streptococcus spp. 

Other causes include:

• Fungus, such as blastomycosis and mycobacterium
• Trauma, such as a wound caused by sharp edges of the whelping box or, rarely, a puppy scratching the teat while nursing
• A damp and unsanitary environment
• Prolonged milk stasis, or a buildup of milk
• Septicemia, or sepsis
• Death of newborn puppies

How Is Mastitis in Dogs Diagnosed?

Mastitis in dogs is typically diagnosed using a physical exam and medical history. Additional testing, including blood work, cytology, milk or fluid culture, X-rays, ultrasound, or biopsy, may be used to determine the type and severity of mastitis and guide treatment.

Physical Exam and Medical History

Your veterinarian will begin with a physical exam and any information you can provide about your dog.

After the physical exam and history are taken, further diagnostic testing may be done to confirm the severity and type of mastitis so an appropriate course of treatment can be selected.

Blood Work

Blood work, such as a CBC and biochemistry, may be done to evaluate:

• Elevated white blood cell count (WBC), which can indicate a severe case of mastitis
• Platelet abnormalities, which can indicate gangrenous mastitis and sepsis
• Dehydration

Cytology and Culture

Cytology may reveal an increase in white blood cells and either bacteria or, rarely, fungus. During cytology, the veterinarian examines groups of cells to detect abnormalities.

A culture of milk or fluid from the gland may be sent to a laboratory to help the veterinarian determine which medications to prescribe.

X-Rays and Ultrasound

X-rays may be used to confirm or rule out gangrenous mastitis.

An ultrasound may also be performed to determine whether there are abnormal changes in blood flow or tissue definition.

Biopsy and Histopathology

Samples of tissue may be taken and sent to a laboratory for evaluation (biopsy/histopathology) to confirm mastitis and rule out cancer.

How Is Mastitis in Dogs Treated?

Treatment for mastitis in dogs depends on the type and severity and may include antibiotics, intravenous (IV) fluids, pain medication, topical therapy, drainage of the affected glands, or surgery.

Treatment for Severe Mastitis

Severe cases require hospitalization along with IV fluids, pain medication, and antibiotics.

Surgical therapy may be needed for necrotic (dead) tissue, which must be drained, flushed, and removed. Antibiotic therapy tends to last for two to three weeks.

Antibiotics

Acute mastitis is treated using broad-spectrum antibiotics, while chronic mastitis is treated based on culture and sensitivity results.

Because mastitis affects both the mother and puppies, the mother is started on antibiotics based on the pH of the milk or fluid expressed from the gland until culture results from the cytology come back from the laboratory.

It is important to know the age of the puppies and whether they are still nursing, as some antibiotics may be harmful to them.

Hand-Milking and Warm Compresses

In addition to oral medication, topical therapy may be needed.

If the mother is still nursing, infected glands are milked by hand every six hours until signs of inflammation, such as heat, swelling, redness, and pain, improve.

Before milking, warm compresses may be applied to encourage drainage.

Massage and Cold Laser Therapy

If the gland is minimally painful, massage may be used to encourage blood flow and help break up congested tissue.

Cold laser therapy may be recommended to help reduce pain and inflammation. Cold laser therapy is a noninvasive procedure that uses a specific frequency of light to stimulate tissue healing and improve blood circulation to areas such as the skin and mammary tissue.

Cabbage Compresses

Cabbage compresses may also be used to decrease inflammation. Not much is understood about what makes cabbage helpful, but it is believed that a cabbage compress may be beneficial because it acts as a cold compress to relieve mild inflammation.

This therapy may be done in the clinic if the mother is hospitalized or recommended as part of at-home care. After treatment with cabbage compresses, puppies can nurse from affected glands when the wraps are removed.

Nursing and Puppy Nutrition

Continuing to nurse puppies prevents milk stasis and helps with drainage.

If the mother is taking antibiotics, probiotics may be helpful to the mother and puppies to help maintain gut flora and prevent diarrhea.

In some cases, puppies must be weaned early or provided with an alternative source of nutrition, including when:

• Multiple glands are abscessed
• An antibiotic is needed that is unsafe in neonates
• The mother is systemically ill
• The mother refuses to nurse

Treating Mastitis Associated With Phantom Pregnancy

Treatment of mastitis associated with a phantom pregnancy may include antibiotic therapy and cabbage leaf therapy.

Phantom pregnancy is also known as pseudopregnancy or false pregnancy. This occurs when a dog displays maternal behavior in combination with the physical signs of heat followed by signs of pregnancy without being pregnant.

This behavior can occur in an intact female dog and is treated by removing the object, such as a toy or blanket, that is being “mothered.”

Recovery and Management of Mastitis in Dogs

Dogs diagnosed with acute or chronic mastitis generally have a good prognosis. Clinical signs should clear up within about two to three weeks in response to treatment.

If mastitis does not respond to treatment or if a dog has gangrenous mastitis associated with septicemia, the prognosis is guarded.

How To Reduce the Risk of Mastitis in Dogs

The following steps can help reduce the risk of mastitis in dogs:

• Trim puppies' nails to reduce wounds to the mother that may lead to infection.
• Monitor puppies to make sure they are nursing from all glands to avoid sudden and prolonged milk stasis. If they are not nursing from all glands, it is OK to move them around.
• Keep the area where the mother and puppies are housed clean, dry, and free of sharp edges to prevent an environment where bacteria can thrive.
• Change bedding in the nursing environment at least one to two times per day and scrub the box daily to reduce bacteria.