FEMALE DOGS & CATS
Spaying, also known as an ovariohysterectomy, involves the removal of the ovaries and uterus. This eliminates the possibility of a dog or cat getting pregnant as well as developing ovarian or uterine cancer. Unspayed dogs and cats can commonly develop a bacterial infection in their uterus called pyometra. Pyometra is especially common in older unspayed dogs and cats. This infection can spread to the bloodstream and cause sepsis (systemic infection) which can lead to renal (kidney) failure. Death can occur as a result of renal failure, sepsis, or uterine rupture. Treatment for pyometra involves immediate spay, but this may not be able to save an animal that is already debilitated. Spaying dogs and cats while they are young and healthy is the best preventative.
Spaying also drastically reduces the risk of mammary cancer in dogs and cats. Mammary tumors are the most common tumors in female dogs, with an incidence 3.4%, and the third most common tumor of female cats, with an incidence of 2.5%. Mammary cancer is malignant in about 50% of dogs and >90% of cats. Once a mammary tumor spread to the lungs and bones, the cancer is fatal. An unspayed dog is 12 times more likely to develop mammary cancer than a dog that has been spayed before her first heat (6-8 months of age) and 4 times more likely to develop mammary cancer than a dog that has been spayed after 2 heats. An unspayed cat is 7 times more likely to develop mammary tumors. The benefit of spaying in reducing the incidence of mammary cancer declines with age and the number of estrous cycles, but reduced risk has been found in spaying animals as old as 9 years of age (1).
Spaying dogs and cats also reduces the risks associated with giving birth. A small birth canal due to narrowing (ie: pelvic fracture) or genetics may make giving birth dangerous. Inadequate body size, like toy breeds, can also leave dogs too weak to give birth naturally. Most of these cases require a cesarian section in order to save the dog or cat’s life. Smaller breed dogs are also more likely to develop eclampsia once they start nursing puppies, in which case their blood calcium decreases significantly. Without rapid treatment with IV calcium, the dog will likely develop seizures and die. Overall, the best way to prevent the dangerous health problems above is spaying your pet when they are young and healthy.