You're right, I've been using these articles for a long time and I need to update my list
I'm also going by personal experience of working at shelters and spay/neuter clinics where I've dealt with pediatric spays/neuters on almost a daily basis for the past 10+ years. I've worked with many vets and everyone of them was a supporter of pediatric spays and neuters. They say the surgeries are much easier therefore the puppies/kittens have to be under anesthesia for a significantly less amount of time. They also recover a lot faster with less complications. Here are a couple of more recent articles I found on a quick google search and I'll do some more in depth research in the next week and get some more:
wvc.omnibooksonline.com/data/papers/2010_V273.pdf
"There are several advantages to pediatric spay/neuter. In addition to the commonly accepted health benefits associated with ovariohysterectomy and castration, pediatric spay/neuter offers additional advantages. It is an effective tool in dealing with the overpopulation of unwanted dogs and cats. The surgical procedures are easier, faster, and less expensive. The incidence of perioperative complications is low as the surgical procedures and, thus, the anesthetic episodes, are significantly shorter. Anesthetic recovery and healing time is shorter."
"Obesity is a multi-factorial problem with a tendency to occur regardless of the age an animal is spayed. A long-term study conducted at Cornell found a decrease in obesity for both male and female dogs that had undergone pediatric ovariohysterectomy.
Initial concerns that pediatric spay/neuter may result in stunted growth have proven to be false. Removal of the hormonal influence actually results in a delayed closure of growth plates. The long bones of animals that undergo pediatric spay/neuter are actually a little longer than those of animals neutered after 6 months of age. There is no clinical significance to the delayed physeal closure.
Some have questioned if early age spay neuter results in an increased incidence of hip dysplasia. Research on this has proven to be equivocal. A study at Texas A&M has shown no increase in hip dysplasia, while a study at Cornell showed a slight increase in incidence. Interestingly, the Cornell study also showed that dogs sterilized at a traditional age were 3 times more likely to be euthanized due to hip dysplasia. This suggests that if early-age gonadectomy increases the incidence of hip dysplasia it may be a less severe form."
Early Spay And Neuter | MyPetsDoctor.com
"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."
"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."
