Why Spay or Neuter?
Traditionally, veterinarians have advised that dogs be spayed or neutered early, preferably by six months of age, as a way of controlling the population of stray pets and reducing the incidence of reproductive diseases. This approach was also thought to minimize the anesthetic risks associated with surgery in young puppies.
However, recent research has cast doubt on whether this is the optimal practice. Studies have identified various impacts of spaying and neutering on four areas of health: weight, orthopedic disease, cancer, and urinary health. In this response, I will summarize the general findings in each of these areas and provide practical recommendations for dog owners.
Weight
Studies have linked spaying and neutering to weight gain in dogs and have shown a moderate increase in the risk of obesity in such cases. However, these studies did not find any significant difference in the risk of obesity based on the age at which spaying or neutering was performed.
While spaying and neutering does decrease metabolic rate, it is important to note that other factors such as insufficient exercise and excessive calorie intake play a much more significant role in the obesity epidemic. Nonetheless, dogs that have been spayed or neutered can still maintain a healthy weight if they are properly fed and exercised.
Orthopedic Disease
One of the areas with the most clearly defined risks and benefits is spaying and neutering. Research has shown that performing these procedures before skeletal maturity (i.e., before the growth plates have closed) can cause a delay in the closure of growth plates, resulting in disproportionately long limbs. This can alter the stress and load on the joints, increasing the risk of orthopedic diseases such as cranial cruciate rupture (similar to an ACL tear) and hip dysplasia.
The risk is particularly high in large and giant breed dogs (weighing over 50 pounds as adults) who are already more susceptible to orthopedic disease and whose growth plates close at a later age than smaller dogs. Therefore, it is recommended that owners of large and giant breed dogs wait until their pets reach skeletal maturity (typically between 12-15 months of age) before spaying or neutering them.
Cancer
The role of spaying and neutering in preventing cancer is difficult to define, particularly in terms of associated risks, even though orthopedic diseases have clearly defined risks and benefits. It has long been established that timely spaying or neutering can prevent uterine infections, ovarian, vaginal, and testicular tumors.
When spaying is done before the first heat cycle, the incidence of mammary cancer can be reduced by 99.5%. If spaying is done after the first heat cycle but before the second, the incidence decreases by 92%. Spaying after the second heat cycle decreases the incidence rate by 74%, whereas spaying after the third heat cycle provides only minimal protection against mammary cancer. Additionally, spaying or neutering at any age eliminates the potential for uterine infections, ovarian, and testicular cancer by removing the affected organ.
Urinary Health
Neutered dogs experience a significant reduction in the occurrence of benign prostatic hyperplasia (BPH). However, spayed or neutered dogs exhibit a slight rise in bladder inflammation and a moderate increase in urinary incontinence.
In Summary
It is highly recommended to spay or neuter dogs that will not be used for breeding purposes, as it can have many positive impacts such as controlling the population, preventing certain reproductive problems, and increasing the overall lifespan of dogs.
The appropriate age to spay or neuter a dog can vary based on their individual health and size. Generally, for small breed dogs (less than 50 pounds), spaying is recommended at around 6 months of age. For large breed dogs (greater than 50 pounds), it is recommended to wait until after their skeletal maturity, but before the second heat cycle (usually around 12-15 months) for spaying female dogs, or anytime after skeletal maturity for male dogs.
However, some people may still prefer to spay or neuter their dogs early for personal reasons, and we are happy to accommodate such requests. Ultimately, we believe that informed decisions are the best decisions, and we want to provide as much information as possible to help pet owners make the best choices for their furry friends.