Spay and Neuter Surgery: Why and When?

By: Michael Lamping, DVM

I am frequently asked why pets should be spayed or neutered and at what age the surgery should be performed.  I recommend that cats and dogs be surgically spayed or neutered when they are 5-6 months old if there is no serious intention to breed them.  Most juvenile cats and dogs enter puberty when they near 7-9 months old.  Females show symptoms of their first heat and males begin to show interest in females at that time.  It is best to spay and neuter before the first heat and before problem behaviors become ingrained habits.  Male dog and cat behavior is often aided by early sterilization.  Since they are not motivated to find "in-heat" females, they are less likely to roam, fight, or mark their territory, and they are not distracted during training.

One of the risks in waiting to "fix" pets later in life is that intact (non-spayed) female dogs are highly susceptible to mammary cancer.  It is the most common cancer of female canines. The risk of mammary cancer is reduced by 99.95% if they are spayed prior to the first heat.

Though older dogs bring about more concerns regarding anesthetic safety, surgery is still recommended to prevent illness.  I once spayed a 13 year old poodle with a life-threatening infection called pyometra (an infection within the uterus).   She was so weak she could not stand, and she was not eating.  Without the surgery, she would have died within a week.   Fortunately, she recovered well.  If the owners had come in one year earlier when she was 12 years old, the surgery and anesthesia would have been less risky and less expensive.

I have performed surgery on several older male dogs with testicular cancer.  Invariably there are other problems present such as prostate infection, prostate cysts, or even bone marrow suppression.  These disorders complicate the treatment and recovery and are avoided by neutering at a young age.