What We are Saying About Spaying and Neutering is Changing (Just A Little)
Perhaps you have recently acquired a new puppy or kitten. Perhaps you are considering it. If so, congratulations! Exciting times are ahead. The typical schedule of when the puppy or kitten should see a veterinarian is at 8, 12 and 16 weeks of age. If your puppy or kitten is already older than that, we suggest an exam shortly after obtaining the pet. At these initial visits, one of the many things discussed is if the pet will be spayed or neutered, and if so when.
It is still true that if the pet is not to be used for show or for responsible breeding, it is recommended the pet is spayed or neutered. Spaying your female will help reduce the risk of mammary tumors, uterine tumors and infection, and unintentional pregnancy. Neutering your male will help reduce prostatic enlargement and testicular tumors. Regarding behavior, proper training is your best tool, but the pet being spayed or neutered may help with their trainability. As a side note, anytime a pet is spayed or neuter, their calorie intake must immediately be reduced to avoid the pet becoming overweight, as their metabolism will slow down. We typically recommend reducing calorie intake by 25%.
Where the conversation is changing is when to perform the spay and neuter surgery. The answer is different for cats and dogs. The American Association of Feline Practioners (AAFP) and the Veterinary Task Force on Feline Sterilization recommends the spay or neuter be performed for cats at five months of age. Their consensus is based on the known benefits of sterilization and the lack of evidence for harm related to performing the surgery at a younger age. Typically this would mean making arrangements for the surgery at the last kitten vaccine appointment which is usually at 16 weeks of age. A link for this concise and informative document from the Task Force is listed below.
Dogs are a little bit of a different story. It’s been well established that performing the spay in a female dog prior to her first estrus (heat cycle) will reduce her risk of mammary tumors later in life significantly. That’s a pretty powerful tool as a pet owner. Performing the spay after one estrus cycle still reduces the risk somewhat; after the second cycle that particular benefit is no longer there, but there is still the reduction of other concerns, namely pyometra, or uterine infection. An intact female dog is under the influence of progresterone in large part. The progresterone contributes to changes in the inside lining of the uterus which predispose to infection. Pyometra is not an uncommon condition in intact female dogs; the treatment for pyometra is a spay surgery on an emergency basis.
However, valid data (meaning it was established with proper studies) is emerging that in larger breed dogs, delaying the spay or neuter may be beneficial. To date the studies have been done in Golden Retrievers, but it is likely there is cross over to other breeds.
The University of California -Davis School of Veterinary Medicine completed a restrospective (looking into the past) study by reviewing records of Golden Retrievers and comparing the incidence of certain orthopedic diseases and some cancers between intact and sterilized male and female dogs. Orthopedic diseases looked at were hip dysplasia and cruciate ligament disease; cancers looked at were lymphosarcoma, mast cell tumors, and hemangiosarcoma. The study found that intact males and females had a lower incidence of hip dysplasia, cruciate ligament disease and lymphosarcoma. There was an increased risk of hemangiosarcoma and mast cell tumors in females spayed later in life. A couple of links with reviews of the UC-Davis study are below; I encourage you to review it.
So there are no clear answers. Ultimately, it is best for the pet owner and veterinarian to work together, discuss risk vs benefit, and discuss goals. The veterinarian should help you as you decide when the spay or neuter is best for your pet, as each situation is individualized. Practical matters such as when the family is best able to care for their post-operative pet should also be considered. The above is our general framework to start the conversation for what was once thought to be a relatively straight-forward topic.
Hollee Kubik, DVM