Most veterinarians agree that the benefits outweigh the risks. However, there are some possible risks that every owner needs to consider:
• Urinary incontinence for females. There is a known increased rate of urinary incontinence (weak bladder) with spayed females. Of female dogs that are spayed, approximately 20% will develop incontinence sometime during their lifetimes. Incontinence can develop shortly after the procedure or many years later. Many vets suggest that waiting until the age of 3 months will cut down on the chance of later developing this.
- For these listed possible risks, many veterinary experts admit that there is not enough supporting research to conclude if any of these risks are valid.
• Cardiac tumors. There is much debate on this topic. At the time of this writing, essentially just 1 study (by Ware and Hopper - Journal of Veterinary Internal Medicine, March/April 1999) concluded that spaying and neutering increased the risk of cardiac tumors; 4 times greater for females and only slighter greater for males.
• Increased rate of other cancers. Again, there is much debate about this. Some studies show that spaying and neutering prevent cancers. Others studies show it increases the risk. Specifically, some studies have concluded that spay/neutering increases: Osteosarcoma (a type of bone cancer), bladder and prostate cancer (a 2002 study showed prostate cancer was 4 times more likely to develop with neutered males; a 2007 study showed both were 3 to 4 times more likely) and lymphoma (studies show a very slight risk of increase for spayed females).
• Delay in growth-plate closure. This refers to growth plates closing later than normal, leading to possible increase of bone fractures. It may also lead to a dog growing a bit larger than he/she would otherwise. Just as many vets agree than those that disagree. It is generally accepted that growth plates may close a bit later (12 to 18 months later), though this equals a difference of just millimeters seen on x-rays.