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This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Here are 10 facts about breast cancer (also called mammary cancer or neoplasia) which is common in dogs.

  • Breast cancer is the second most common tumour type, and the most common malignant cancer in dogs
  • It affects 2.6/1000 sexually entire (non-neutered) bitches
  • Some breeds have a relatively  high risk of developing breast cancer including the English Setter, English Spaniels, Poodles and Terriers
  • Some breeds have a relatively low risk of developing breast cancer including the Boxer* and Chihuahua
  • Breast cancer is influenced by sex hormones and neutering bitches significantly reduces the occurrence of breast cancer:
    • Before the first oestrus - reduces risk to 0.5%
    • After first oestrus but before second oestrus - reduces risk to 8%
    • After second oestrus - reduces risk to 13-26%
  • Bitches that are thin/"lean" at the end of their growth period (9-12 moths) are less likely to develop breast cancer than bitches that are overweight
  • About 50% of breast tumours in dogs are benign
  • About 25% of malignant tumours result in death of the patient
  • The larger the tumours at the time of diagnosis the worse the prognosis - likelihood of recurrence increases after removal of larger lumps - so breast tumours should be removed as early as possible.
  • Surgical removal with ovariohysterectomy offers the best prognosis when treating breast cancer in dogs.

* This is interesting because in general the Boxer has a high risk of developing other forms of cancer.


Updated October 2013