A female dog spayed before her first heat will have a near zero chance of developing
mammary cancer. After the first heat, this incidence climbs to 7% and after the second
heat the risk is 25% (one in four!). It is easy to see that an early spay can completely
prevent what is frequently a very difficult and potentially fatal form of cancer "Pyometra" is the life-threatening infection of the uterus which generally occurs in
middle-aged to older female dogs in the six weeks following heat. The hormone
"progesterone," which primes the uterus for potential pregnancy, does so by causing
proliferation of the blood-filled uterine lining and suppression of uterine immune
function. It is thus easy during heat for bacteria in the vagina to ascend to the uterus to
cause infection. The uterus with pyometra swells dramatically and is filled with pus,
bacteria, dying tissue, and toxins. Without treatment, the pet is expected to die. Despite
her serious medical state, she must be spayed quickly if her life is to be saved.
http://www.gsdhelpline.com/spay2.htm In the United States, most dogs are spayed between 5 and 8 months of age. Many humane shelters and veterinarians are starting to spay female animals at a younger age, even at 2 months. This early spaying does not affect the growth rate, and there are no appreciable differences in skeletal, physical, or behavioral development between those animals spayed early than those spayed at a more traditional age. It must be remembered that younger animals may need different anesthetics and are more prone to hypothermia (lower than normal body temperature) during surgery. As long as procedures are modified to account for these differences, early neutering is very safe. In fact, animals spayed at a younger age often have faster recoveries than those spayed when they are older.
