Breast Cancer in Dogs: Understanding, Detecting, and Treating Canine Mammary Tumors

Breast Cancer in Dogs: Understanding, Detecting, and Treating Canine Mammary Tumors

Breast cancer, or mammary tumors, is a significant health concern for female dogs, particularly those who are unspayed or older. Understanding the signs, causes, and treatment options for breast cancer in dogs can help pet owners detect issues early and seek appropriate veterinary care. This article provides a comprehensive guide on canine breast cancer, focusing on symptoms, risk factors, diagnosis, and treatment.

What is Breast Cancer in Dogs?

Breast cancer in dogs refers to malignant tumors that develop in the mammary glands. These tumors can be benign (non-cancerous) or malignant (cancerous), with malignant tumors posing a greater risk to the dog's health. Mammary tumors are most common in unspayed female dogs over the age of six, but they can also occur in spayed females and, rarely, in male dogs.

Risk Factors for Canine Breast Cancer

1. Spaying Status

The risk of developing mammary tumors is significantly higher in unspayed female dogs. Spaying a dog before her first heat cycle can reduce the risk of mammary cancer by up to 90%.

2. Age

Older dogs are more likely to develop mammary tumors. The risk increases with age, particularly in dogs over six years old.

3. Breed

Certain breeds are more predisposed to mammary tumors, including:

  • Poodles
  • Spaniels
  • German Shepherds
  • Terriers

4. Hormonal Factors

Hormonal influences, such as exposure to estrogen and progesterone, play a significant role in the development of mammary tumors. Dogs that have had multiple heat cycles or have been treated with hormone-based medications are at higher risk.

Symptoms of Breast Cancer in Dogs

Early detection of mammary tumors is crucial for successful treatment. Common symptoms include:

  • Lumps or Masses: Noticeable lumps or masses in the mammary gland area. These can be hard or soft, movable or fixed.
  • Swelling: Swelling or enlargement of the mammary glands.
  • Ulceration: Open sores or ulcers on the mammary glands.
  • Discharge: Unusual discharge from the nipples.
  • Pain or Discomfort: Signs of pain or discomfort, especially when the area is touched.

Diagnosing Breast Cancer in Dogs

If you notice any of the above symptoms in your dog, it is essential to seek veterinary care promptly. Diagnosis typically involves:

  • Physical Examination: The vet will palpate the mammary glands to identify any lumps or abnormalities.
  • Fine Needle Aspiration (FNA): A sample of cells from the lump is extracted and examined under a microscope.
  • Biopsy: A tissue sample is taken from the lump for histopathological analysis to determine if it is malignant.
  • Imaging Tests: X-rays or ultrasounds may be used to check for metastasis (spread of cancer) to other parts of the body.

Treatment Options for Canine Breast Cancer

The treatment plan for mammary tumors in dogs depends on the tumor's type, size, and stage. Common treatment options include:

1. Surgery

Surgical removal of the tumor is the most common and effective treatment. Depending on the tumor's size and location, the surgery may involve:

  • Lumpectomy: Removal of the tumor only.
  • Mastectomy: Removal of one or more mammary glands.

2. Chemotherapy

Chemotherapy may be recommended, especially if the cancer has spread. It involves the use of drugs to kill cancer cells and prevent further spread.

3. Radiation Therapy

Radiation therapy can be used to target and destroy cancerous cells in specific areas, often in conjunction with surgery and chemotherapy.

4. Palliative Care

For advanced cases where curative treatment is not possible, palliative care focuses on managing symptoms and improving the dog's quality of life.

Prevention and Early Detection

Regular Veterinary Check-ups

Routine veterinary visits are crucial for early detection and monitoring of any health changes.


Spaying your dog before her first heat cycle is the most effective way to reduce the risk of mammary tumors.

Home Monitoring

Regularly check your dog’s mammary glands for any lumps, swelling, or changes, and consult your vet if you find anything unusual.


Breast cancer in dogs is a serious condition that requires prompt attention and appropriate treatment. Understanding the risk factors, recognizing the symptoms, and seeking early veterinary care can significantly improve the outcome for affected dogs. By being vigilant and proactive, pet owners can help ensure their dogs live healthy, happy lives. If you notice any signs of mammary tumors in your dog, consult your veterinarian immediately for a thorough examination and treatment plan.

Staying informed about breast cancer in dogs and taking preventive measures can make a significant difference in your pet’s health and well-being.

Retour au blog