Breast cancer: Estrogen is one of the primary causes of canine breast cancer, the most common malignant tumor in dogs. Animals that are spayed prior to one year of age very rarely develop this malignancy. However, it is very common in unspayed females. The chances of reaching 10 years of age without developing this potentially fatal tumor is less than 11% in some breeds with normal hormone production. If the dog is spayed later in life, it may still decrease the chances for this cancer to develop. The best way to insure your dog is spared from breast cancer is to have an OHE performed before her first heat
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