The study population was 29 intact males, 26 neutered males, 24 intact females, and 37 spayed females, for a sample size of 116 cases. The occurrence of at least one joint disorder was seen in 7 percent of the intact males and in none of the intact females. None of the neutered males or females had a noteworthy occurrence of a joint disorder. The occurrence of one or more of the cancers followed was 11 percent for intact males and none for the intact females. There was no evident increase of cancers in males with neutering, and in females, there was an increase of cancer to 40 percent in those spayed at <6 mo., which may have reached significance with a larger sample size. For females left intact, 4 percent were diagnosed with MC, and 16 percent were diagnosed with PYO. Of females spayed at 6–11 mo., 13 percent had UI. Lacking a noticeable occurrence of increased joint disorders or cancers in neutered males, those wishing to neuter a male should decide on the appropriate age. For females, given the apparent risks of cancers with spaying at <6 mo. and UI with spaying at 6–11 mo., the guideline is to delay spaying until the female is a year old.
8. Hoffman JM, Creevy KE, Promislow DEL. Reproductive capability is associated with lifespan and cause of death in companion dogs. PLoS ONE. (2013) 8:e61082. doi: 10.1371/journal.pone.0061082
The study population was 92 intact males, 87 neutered males, 84 intact females, and 113 spayed females for a total sample of 376 cases. As in other small dogs, joint disorders were rare; none of the intact males, and just 2 percent of intact females had one or more joint disorders. Neutering was not associated with any increase in this measure in either sex. In intact males, 3 percent, and in intact females none, had one or more of the cancers followed. There was no evident increase in cancer occurrence in either sex with neutering at any age. In females left intact, MC was seen in 1 percent, as was PYO. In those spayed at 2–8 years, MC was diagnosed in 3 percent. UI was not diagnosed in any females. Lacking a noticeable occurrence of increased joint disorders or cancers in neutered males or females, those wishing to neuter should decide on the appropriate age.
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The present study examined the occurrence in both sexes of the joint disorders: HD, CCL and ED. Also examined in both sexes were the cancers LSA, HSA, MCT, and OSA, because these had been shown in some multi-breed studies to be increased in risks with neutering. In addition, mammary cancer (MC), pyometra (PYO), and urinary incontinence (UI) were examined in female dogs. Of interest was the possible association of early neutering and the occurrence of intervertebral disc disorders (IDD) in the Corgi and Dachshund, two breeds known to be at risk for these diseases. All of the above diseases were examined with regard to dogs neutered in one of the age periods of: <6 mo., 6–11 mo., 1 year (12 to <24 mo.) or 2–8 years, or left intact. The diseases were tracked until the dogs were last seen at the hospital, or through 11 years of age, if seen past their 12th birthday.
Weight
Spaying and neutering have long been implicated in weight gain and the studies confirmed there is moderate increase in the risk of obesity for dogs who have been spayed and neutered. However, the studies did not show the age of spaying or neutering to change the risk of obesity. It is also important to note that while spaying and neutering decrease metabolic rate, environmental factors such as lack of exercise and excessive calorie intake play much bigger roles in the obesity epidemic and dogs who have been spayed or neutered will still maintain a healthy weight if fed and exercised appropriately.
I graduated from veterinary school in 1982. As I look back, I don’t recall hearing the words “pet overpopulation” or “shelter medicine,” which is likely because I was not listening. Most of us were zeroed in on pharmacology, pathology, physiology, and dermatology—and bracketology during March Madness.
I saw that the tears shed for injured, abused, and homeless animals were not, for the most part, from crazy people, but rather from normal dedicated, hard-working, caring individuals. They did their best without many supplies, no room to spare for animal housing, and little money.
Many terms are associated with surgical sterilization of dogs and cats. While neutering is often associated—especially by the general public—with male pets, it technically applies to both female and male animals. For this article, neutering is used to describe surgical sterilization of male and female dogs and cats—castration and spaying, respectively.
My request is that we, as veterinarians, consider the devastating effects of waiting too long to neuter an animal. Mammary cancer—which can be prevented by spaying prior to first estrus—leads to premature death in cats and dogs every day. Hormone-related behavioral issues that develop as puppies and kittens sexually mature commonly lead pet owners to part with their pets.
As I gradually became more involved with the local humane society, I realized that no matter how many unwanted pets were given to good homes, the supply of new homeless pets was continually overwhelming. As a result of this hopeless situation, my specialty became pet population control, specifically neutering.