Canine mastitis

By Dr. Mikel Delgado, PhD

Mastitis is when your dog has inflammation in one or more of her mammary glands. It is usually seen in dogs who are nursing or who recently stopped nursing. 

The most common cause is a bacterial infection, as bacteria can enter the mammary glands from any injury to the nipples. Mastitis can also be caused by a fungal infection, or occur if milk is not flowing properly. 

Prevention of mastitis

The best way to address canine mastitis is to do your best to prevent it! Be sure to:

• Keep the nursing area clean and disinfected, and free of obstructions that could cause injuries
• Change whelping box bedding frequently
• Keep puppy nails trimmed to prevent scratches
• Check your dog’s mammary glands daily for swelling, redness, temperature changes, discharge, and sensitivity
• Weigh puppies daily to ensure they are growing

Signs of mastitis

Early signs of mastitis can include puppies that are not gaining weight. You may also notice that your dog has swollen or painful mammary glands and may refuse to allow her puppies to nurse. Mastitis can progress to visible redness, or even wounds and discharge of pus or blood. When mastitis is severe, dogs may become lethargic, have a fever, or stop eating. Mastitis can progress quickly and even be deadly (to both mom and puppies), so don’t ignore early signs, and be sure to contact your veterinarian if you suspect your dog has mastitis.

Diagnosis of mastitis

Many cases of mastitis are diagnosed by physical examination by a veterinarian. In addition to a physical examination, your veterinarian may examine your dog’s milk under a microscope or do a bacterial culture. A complete blood count (CBC) can assess the increase in white blood cells that indicate infection. Radiographs or ultrasound may also help your veterinarian rule out gangrene (dead tissue) or other structural problems.

Treatment of mastitis

Mastitis is generally treated at home with antibiotics and pain medication. 

In addition, you can provide supportive care via:

• Encourage milk expression via gentle hand-milking, or by allowing puppies to continue to nurse
• Apply a warm compress for a few hours, alternating with removing for a few hours before re-applying
• Cabbage leaf compress: apply raw cabbage leaves to the mammary glands and keep in place for 2-3 hours at a time with a t-shirt or loose bandage

Severe cases of mastitis may require hospitalization, intravenous fluids and supportive care, or even surgery to remove dead tissue.

Outlook for dogs with mastitis

With treatment, most cases of mastitis usually resolve in two to three weeks. Severe cases of mastitis have a more guarded prognosis. Puppies can usually continue to nurse, but should be checked for weight gain and given supportive care, such as supplemental feeding, if needed.

Resources

VCA: Mastitis in Dogs

Kaszak, I., Ruszczak, A., Kanafa, S., Piłaszewicz, O. W., Sacharczuk, M., & Jurka, P. (2018). New insights of canine mastitis—A review. Animal Science Papers and Reports, 36(1), 33-44.