Veterinary Wellness Blog

Spaying and Neutering-What is it and Why do it?

July 3, 2012

A neuter, or castration, is a surgical procedure in male pets where both testicles are removed.
A spay, or ovariohysterectomy (OHE), is a surgical procedure in female pets where both ovaries and the uterus are removed.

There are many benefits to having your pet spayed or neutered including both health and behavior benefits.  These include:

• Neutered and spayed pets are less territorial and are less likely to roam.  Research indicates that 80% of dogs hit by cars are non-neutered males.
• Spayed females typically stay healthier and live longer.  They have a lower incidence of mammary tumors (breast cancer) and no uterine or ovarian cancers.
• Neutered pets can’t develop testicular tumors, which are the second most common cancer in males, and they also have a lower incidence of prostate cancer.
• Dogs spayed before their first heat cycle have a less than 1% risk of developing mammary tumors, dogs spayed after 1 heat cycle have an 8% risk (or about 1 in 10 will develop a tumor), and dogs spayed after 2 heat cycles have a 26% risk of developing mammary tumors (or about 1 in 4).
• Unspayed females have a 7 times higher risk of developing mammary tumors than their spayed counterparts.  Mammary tumors are the most common tumors in female dogs, and are the third most common type of cancer in female cats, and in cats more than 90% of them are malignant, or likely to spread.
• One quarter of unsprayed females will develop an infection of the uterus, called a pyometra, and spaying greatly decreases the potential for this sometimes fatal illness.
• Neutered and spayed pets are less aggressive, less likely to fight, and less likely to bite, as documented in multiple studies.
• Neutered pets such as dogs, cats, and rabbits are less likely to mark furniture, walls, and rugs.
• Female rabbits over the age of 4 have a 1 in 2 up to 90% chance of developing uterine cancer.
• Female guinea pigs that get pregnant after 6 months of age will likely require a C-section to give birth, as their hips bones mature after this age and make the birth canal too narrow.
• Female ferrets that go into heat can develop a fatal problem where the hormone estrogen causes the bone marrow to stop producing red blood cells, leading to a severe anemia that is not reversible.
• Sometimes we may tell you that your male pet is cryptorchid.  During development, testicles are formed near the kidneys, and gradually make their way into the scrotum.  If for some reason this does not occur, the patient is called cryptorchid.  The testicle(s) can be anywhere from inside the abdomen to almost in the scrotum.  This is a heredity problem, so these animals should be neutered to prevent passing this trait on.  Internal testicles could also render the pet infertile.  Lastly, testicles that are retained inside the abdomen are 13 times more likely to develop cancer.

Due to these factors, we recommend spaying and neutering all pets.   We generally recommend performing these surgeries when your dog or cat is 4-6 months old, although health and behavior benefits may be seen at any age.  For other pets, we recommend spaying or neutering before they reach sexual maturity (see table below).
pet                 age at sexual maturity
dog                  4-12 months
cat                   4-12 months
rabbit               4-8 months
ferret                4-8 months
rat                    6-8 weeks
mouse              6-8 weeks
guinea pig        2-3 months
chinchilla          2-14 months
sugar glider      8-15 months
gerbil                9-18 weeks
hamster            6-8 weeks
hedgehog         2-8 months

Don’t leave your pet at risk, ask us today about getting them fixed!