Does the timing of spaying my dog matter?
So you just added a cute, fuzzy puppy to your family! If you are new to owning a dog, it is likely that you have more than just a few questions about raising your puppy. One of those questions might be; when should my puppy be neutered or spayed? You will likely find that the answer to this question varies. Recent research has suggested that the standard recommendation of 6 months may not be the best practice for all dogs. Studies have suggested that factors such as risk of orthopedic disease and developing certain cancers should be considered when deciding when to spay or neuter your dog. Regardless of the answer for the best timing of spay or neuter, there is overwhelming evidence that spayed or neutered dogs live longer, healthier lives than intact dogs.
Does early spay or neuter cause orthopedic disease?
This may be the area with the most clearly defined risks and benefits. It is well documented that spaying and neutering before skeletal maturity is reached (before the growth plates have closed) will delay closure of the growth plates which will result in disproportionately long limbs. This changes the stress and load on the joints which increases the risk of orthopedic diseases such as cranial cruciate rupture (an ACL tear) and hip dysplasia. This risk is most dramatic in large and giant breed dogs (adult weight over 50 pounds) considering they are already more at risk for orthopedic disease. Their growth plates also close at a later age than smaller dogs.
Because of this, we recommend large and giant breed dogs wait to be spayed or neutered until they reach skeletal maturity (generally between 12-15 months of age).
Does waiting to spay or neuter cause cancer?
Timing of spay or neuter has clearly defined effects on future orthopedic disease. The role of spaying and neutering and cancer correlation is harder to define, especially the risks. We have long known that uterine infections, ovarian, vaginal, and testicular tumors are prevented by timely spaying or neutering. We know that spaying before the first heat cycle reduces the incidence of mammary cancer by 99.5% while spaying after the first heat cycle but before the second decreases the incidence by 92%. Spaying after the second heat cycle decreases the incidence rate by 74%. Spaying after the 3rd heat cycle provides minimal protection against mammary cancer. Spaying or neutering at any age removes the potential for uterine infections, ovarian, and testicular cancer by removing the organ that will be affected.
Cancers such as hemangiosarcoma (blood vessel cancer of the liver and spleen), osteosarcoma (bone cancer), and lymphoma show a mild to moderate increase incidence in dogs who are spayed and neutered. However at this time, it is regardless of the age when they were spayed and neutered.
When should I spay or neuter my dog?
Veterinarians sift through information like the above every day, often with conflicting conclusions, and determine the best recommendations for our individual patients. Research is ongoing and more studies are needed to confirm or refute what we know so far. While the data seems to suggest that spaying and neutering at any age may increase the risk for many conditions and diseases, it may not be that black and white. However, data consistently shows that spayed and neutered dogs have an increased longevity over intact dogs.
At this time, the orthopedic risks for large breed dogs from early spaying and neutering are clear while the cancer risks are less clear. This is because:
- Orthopedic diseases are usually young to middle-aged dog problems and all the dogs in the studies would be equally susceptible to developing orthopedic disease in any case.
- Cancer is most commonly a disease of older dogs and the spayed and neutered dogs tend to live to an older age than intact dogs. Because of this, the decreased incidence of cancer in intact dogs may correlate to the fact that since their life span is less, they are less likely to develop cancer.
At City Dog Vet, we recommend spaying and neutering all dogs who will not be used for breeding due to the positive impacts on population control, the prevention of certain reproductive diseases including cancers, and the overall increased longevity of dogs that are spayed and neutered.
The age to spay or neuter can vary depending on the individual dog. It is important to discuss with your veterinarian the best timing for your dog’s spay or neuter based on the breed and your unique situation. As with all medical decisions about your dog, we want to make sure you have as much information as possible before deciding when to spay or neuter your dog.
-Dr. Sue Roberts