The risk of malignant mammary tumors in dogs spayed prior to their first heat is 0.05%.

It is 8% for dog spayed after one heat, and 26% in dogs spayed after their second heat.

This is Betty, a 10+ year old dachshund that has been bred for many years and never spayed. She lived outside with 32 other dachshunds in a backyard, having learned how nice it is inside only after she was rescued. What does she get for producing so many puppies? Mammary cancer.

All of Woofs & Whiskers funds are currently going toward Betty's $600 radical mastectomy surgery. UPDATE: We have earned enough money to proceed with Betty's surgeries and she has had a full recovery! See photos here.

Aside from the obvious fact that there is a massive problem with overpopulation, spaying and neutering:

greatly reduces the risk of breast cancer and completely eliminates the threat of uterine and ovarian cancer.

prevents testicular cancer and prostate problems, and helps him avoid serious health problems like hernias and perianal tumors.

makes a pet far less likely to develop dominance or aggression-related behavior problems, including possession and food guarding, territory marking (lifting his leg on everything in sight), aggression toward other dogs, and "humping" inappropriate objects.

* From Adopt-a-pet.com

Free and Low-Cost Spay/Neuter Database