Mammary gland (or breast) tumors are the most common types of cancer in unspayed female dogs. About half of these tumors are benign and half are malignant. At the time of diagnosis, half of the malignant tumors would have metastasised.
Mammary Cancer in Dogs: Causes & Risk Factors
While the cause of mammary cancer in dogs is unknown, there are several factors that may influence the development of mammary gland tumors.
1. Sex hormones
Intact female dogs are 7 times more likely to develop mammary cancer than spayed females. Sex hormones such as estrogen and progesterone may contribute to the development and progression of mammary tumor. Spaying removes the reproductive organs, which are the source of these hormones.
Early spaying significantly reduces the risk of mammary cancer. The risk of developing mammary cancer in dogs, if spayed:
before 1st heat = 0.05%
after 1st heat = 8%
after 2nd heat = 26%
Obesity at 12 months of age increases the risk of mammary cancer in dogs, even at a later age.
Dogs have a higher risk of developing mammary cancer if fed a diet high in fat or red meat.
Breed & Age Predisposition
Mammary tumors develop with age. The affected dogs are usually over 6 years of age, with the highest incidence in the age group of 10-12 years. This type of cancer rarely occurs in dogs younger than 2 years of age.
Small and large breeds can develop mammary cancer. Some of the breeds at high risk are Poodles, English Cocker Spaniels, Daschunds, Terrier, Samoyed/White Spitz, Doberman, German Shepherd and Retriever.
What are the warning signs of canine mammary cancer?
See –>Breast Cancer in Dogs Symptoms
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