Early Spay And Neuter

Dear Reader,
Please be aware that the photographs of tissues below are graphic, which is why we have put them at the bottom of the page. Squeamish readers may elect to read the text and forego scrolling all the way down to the pictures.


Bob Barker and many other spay/neuter advocates, as well as the popular press, emphasize the importance of spaying and neutering pets for reasons of pet population control. Of course, with an estimated one to three million dogs and cats euthanized in the United States alone each year (depending on whose statistics you use), and seven dogs and cats born for each new human born, this is certainly a good reason to help control pet overpopulation.

Today, however, we will look at a real-life case that exemplifies two of the most common health complications that occur when pet owners fail to have dogs and cats spayed when they are young.


Mammary gland tumor growth in dogs and cats is greatly influenced by failure to remove the source of sex hormone from the patient while young. Dogs and cats spayed before their first heat cycle have a virtually zero risk of mammary cancer later in life. Those spayed after the first heat cycle still experience a significantly reduced incidence of mammary cancer. After the second heat cycle the beneficial effect is dramatically reduced. However, as you will see further down in this article, benefit is still achieved by having one’s pet spayed at almost any age.

While there are genetic and environmental factors which can influence mammary tumor development in dogs and cats, the effect of estrogen produced by the ovaries is considered to be the primary driving factor in most canine and feline mammary growths.

Benign and malignant tumors occur in both species. In dogs, approximately half of the masses are malignant. In cats the picture is very different. Study results differ, but in the “best” scenario for cats four times as many tumors were malignant as benign. In another study nine out of ten growths were malignant.

Despite modern advances in surgical, chemotherapeutic and radiation treatment of cancer in animals, noone wants his pet to suffer. The facts are clear: the best way to avoid mammary cancer in dogs and cats is to have them spayed before the first heat cycle.


Another hormone-driven problem un-spayed dogs and cats suffer is infection of the uterus, called pyometra. The term derives from the Latin prefix pyo-, which means “pus,” and root metra, which means uterus. “Pus in the uterus” is the most extreme form of the disease, and is life-threatening.

The process usually starts with irregular heat cycles or a condition called pseudopregnancy, in which hormone imbalances cause the uterus to “think” it is pregnant and begin to accumulate fluid to accommodate the pregnancy. In the best case, hormone levels return to normal within sixty days and the fluid is reabsorbed into the body. Pseudopregnancy is likely to recur on future heat cycles.

The worst case is that cysts occur in the ovaries(see photo below, pencil points to cyst in ovary) and continue to produce an imbalance of hormones which maintain the fluid in the uterus. If bacteria from the vaginal vault ascend, pass the cervix and enter the nutrient-rich fluid, infection results. Fecal bacteria are the most common motile bacteria to achieve success and cause the worst infections. Fecal bacteria also produce toxins, thus poisoning the already-infected female dog or cat, and adding to the illness the pet experiences.

In the pictures you see below the uterus of this 11-year old Chihuahua is enlarged to approximately six times normal size. The uterus is fluid-filled and thin-walled. If not handled gingerly during surgical removal the uterus could easily rupture.

In more advanced cases pus (infection) may fill the uterus like a balloon, expanding it to twenty times normal size. If such a uterus bursts, spilling its toxin-heavy load of infection into the abdominal cavity, fast and expert emergency surgery must be performed to save the patient’s life.


Keep in mind that all of this can easily and inexpensively be prevented simply by having one’s pet spayed before the first heat cycle. Even if you have missed that opportunity your pet can benefit from the preventive advantage of having spay surgery later in life. Simply ask your pet’s doctor about preparation for surgery.  MMSPAYN

Pyometra-infected canine uterus
Pyometra-infected canine uterus

Ovarian Cysts frequently produce abnormal levels of female hormones

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