What you need to know to make an informed decision

A spay surgery is an informal way of describing an ovariohysterectomy. This procedure removes the ovaries and the uterus from the female dog.

An ovariohysterectomy is recommended for female dogs not intended for breeding. The incidence of mammary tumors can be decreased when the procedure is performed early in life. This surgery has a "sparing" effect if performed prior to 2.5 years of age. The incidence of mammary tumors in dogs is 1 per 500 for dogs that have been intact for over 2 years. Of these 50% are malignant. Unlike humans, pregnancy did not show a protective effect.

A more study has indicated that the risk increases substantially after the 1st heat. Their information states that if a female has an ovariohysterectomy prior to her first heat, she has an 0.05% risk of occurrence; for one heat the risk increases to 8%; and if two heats the risk increases to 26%. Later spay surgeries reduced the incidence of benign tumors but had no effect on malignant tumors.