The ideal time to spay your pet is before her first heat cycle, which is typically at 5 months of age. Spaying at this age will virtually eliminate the chance of mammary tumors but her risk will increase as each heat cycle occurs (generally having one every 6 months). Mammary cancer in dogs is more common than it is in people and is frequently malignant. Unfortunately there is no benefit for the risk reduction of mammary tumors when spaying after the age of 2 ½. BUT is still strongly recommended for older dogs to prevent the above mentioned conditions, ovarian and uterine tumors and pyometra. We believe early spays also benefit cats in relation to mammary tumors, similar to dogs, but most all mammary tumors in cats are malignant.