Mastitis in Dogs

Mastitis is an infection of the mammary glands that can affect lactating or recently weaned female dogs. It can be painful, serious, and occasionally life-threatening if left untreated. Early recognition and veterinary care are key to preventing complications and ensuring your dog’s comfort and safety.

What Is Mastitis

Mastitis occurs when bacteria enter the mammary tissue, typically through a small wound or cracked skin around the nipple. This leads to inflammation, swelling, and sometimes abscess formation. It most commonly affects dogs who are nursing puppies but can also occur in females with false pregnancies or after weaning.

Signs to Watch For

Dog owners should be on the lookout for the following signs:

• Swollen, firm, or painful mammary glands

• Redness or heat around the nipple area

• Reluctance to nurse puppies

• Discolored milk (yellow, green, or bloody)

• Fever

• Lethargy or decreased appetite

• Crying out when touched

In severe cases, the dog may become systemically ill, showing signs such as vomiting, weakness, or collapse.

Is Mastitis an Emergency?

Mastitis ranges in severity. Mild cases may be uncomfortable but manageable with prompt veterinary care. However, if your dog is showing signs of pain, fever, or systemic illness, it should be treated as an urgent veterinary concern. Mastitis can progress quickly, so do not delay evaluation.

Home Care and Monitoring

While treatment should be guided by your veterinarian, supportive care at home may include:

• Gently applying warm compresses to the affected area to promote drainage

• Ensuring puppies are nursing evenly, if safe to do so

• Preventing trauma to the area

• Keeping the environment clean to reduce bacterial exposure

Do not attempt to express or massage the gland forcefully, as this may worsen inflammation or introduce more bacteria.

Veterinary Treatment and Follow-Up

Your veterinarian will examine your dog and may:

• Perform a physical exam and assess each mammary gland

• Evaluate a sample of milk for infection

• Prescribe antibiotics and anti-inflammatory medication

• Recommend temporary weaning if the infection is severe or milk is no longer safe for puppies

In rare cases where an abscess or tissue death occurs, surgical intervention may be necessary.

Nutrition and Recovery Support

Proper nutrition is essential to support your dog’s immune system during recovery. Nursing mothers require a high-calorie, high-protein diet to maintain body condition and milk production. Your vet may recommend:

• A specific lactation or puppy food

• Vitamin or mineral supplementation, if needed

• Close monitoring of weight and hydration status

For dogs with mastitis unrelated to nursing, caloric needs may differ. Always follow veterinary guidance.

Preventing Mastitis

Prevention focuses on maintaining good hygiene and monitoring nursing dogs closely:

• Keep bedding and whelping areas clean and dry

• Inspect mammary glands daily during lactation

• Prevent puppies from favoring or damaging a single gland

• Address any injuries or cracked skin promptly

The Bottom Line

Mastitis in dogs is a medical condition that can escalate quickly without proper care. By recognizing the signs early and seeking prompt veterinary attention, most cases can be treated effectively. With proper treatment, nutrition, and monitoring, affected dogs usually make a full recovery and can safely continue caring for their puppies.

If you suspect your dog may have mastitis, especially during or after nursing, consult your veterinarian as soon as possible.

Gal Chivvis, DVM

Founder of Critter Care Collective, LLC

Emergency veterinarian, author, independent publisher