The principal benefit of spaying female dogs is the prevention of mammary cancer. A dog spayed before her first heat will have a 0.5% chance of developing mammary cancer later in life. After the first heat, this incidence climbs to 8 percent, and after the second heat the risk approaches 26 percent chance.
Additional reasons to spay a female dog include reducing the incidence of uterine, cervical and ovarian cancer and preventing pyometra (an infection of the uterus), vagina (edema/hyperplasia, prolapse) that are the result of hormones released by the ovaries, and therefore are prevented by Spaying.
Yorkshire Terriers have an increased risk of mammary cancer.
It is advisable that dogs be neutered following SKELETAL MATURITY. Also, when dealing with Yorkshire Terriers it is prudent to wait until maturity so they have the ability to handle the anesthesia. It is a fine line to get the timing down for your dog to spayed. You want them to be fully grown, but before they come into heat.
The major health benefits involved in neutering a dog involve the prostate gland. As dogs age, the prostate will gradually enlarge. This is known as benign prostate hyperplasia or BPH. The prostate under the influence of testosterone is also predisposed to infection. This is an extremely painful and sometime life-threatening condition which is not likely to resolve without neutering and often invasive surgery.
Other medical conditions that are prevented include testicular cancer, along with certain types of hernias and perianal tumors.
Spayed and neutered dogs have also been shown to have increased life expectancy compared to intact dogs, yet there are a number of factors that likely influence these results and a true causation effect cannot be concluded.
Cons: Spayed and neutered dogs are significantly more likely to be overweight or obese. A dog’s metabolism will slow by about 30% after they are spayed or neutered.