Canine spay and neuter has become a hot and controversial topic in the past few decades. Shelter overpopulation quickly became an epidemic in the United States, which resulted in the euthanasia of 670,000 dogs per year. This statistic brought about a strong emotional response and sterilization seemed to be the appropriate solution to the problem. Spay (females) and neuter (males) are surgical procedures in which the reproductive organs of canines are removed. Spay and neuter surgeries eliminate the possibility of unwanted litters and in return limit the number of dogs that enter the shelter system. Spaying and neutering might assist with the overpopulation problem, but it’s important to fully understand the benefits and risks of sterilization before making the decision for your pet.
Early spay and neuter refers to sterilization before a dog goes through puberty. Small breed dogs may reach physical maturity by the time they’re a year old, but large breed dogs can continue growing until they’re two years old. Veterinarians commonly recommend puppies be spayed or neutered by the time they are 6 months of age. Many shelters and rescue organizations sterilize puppies as young as 8-weeks old. The primary goal of early spay and neuter is to prevent unwanted litters. There are a handful of health benefits to early spay and neuter: reduced risk of mammary tumors and testicular cancer, prevention of uterine infections (pyometra), and decreased vascularization to the reproductive organs reduces the risk of hemorrhage in surgery. Dogs that have been neutered may see behavioral benefits such as decreased marking and roaming. In certain cases, dogs that developed aggression during puberty may see improvement in the behavior if castrated soon after the aggression presents.
New research has come out against early spay and neuter. Many canine professionals are recommending dogs not be sterilized until after they’ve reached sexual maturity or around 24 months of age. Although spay and neuter can decrease the risk of certain cancers and pyometra, early spay and neuter can bring on a host of medical conditions. Dogs sterilized at 24 months of age can still reap the benefits of decreased cancer and infection risk without assuming the added dangers associated with pediatric sterilization. Dogs that are sterilized before undergoing puberty experience a higher risk of mast cell tumors, lymphosarcoma and hemangiosarcoma. They also see a 38% increased risk of vaccine reactions. (dvm360.com) Females that are sterilized before puberty may fail to fully develop their vulva and can experience urinary incontinence throughout their life. Early spay and neuter has also been linked to an increase in noise phobias and fearful behavior.
The greatest argument against early sterilization is the orthopedic repercussions. Puppy bones are capped by soft cartilage called growth plates. Puppies’ bones will continue to develop until their growth plates close at around 18 months of age. As puppies go through puberty, they release hormones that aid in the development of bones and eventual closure of their growth plates. Puppies that are sterilized before puberty never receive these hormones and as a result, experience a delay in the closure of their growth plates. This delay allows the long bones to continue to grow to an abnormal length. When this occurs, dogs will grow taller than they should have and are more susceptible to injury. These dogs have a greater risk of canine cruciate ligament ruptures, patellar luxation, and hip dysplasia compared to dogs left intact or sterilized after maturity. The radiographs below show the bones, joints, and growth plates of dogs at 2 weeks, 7 months, and full maturity. Also shown is a stand-alone radiograph of an 8-week old puppy with a fractured leg. Puppies’ bones continue to grow and strengthen as they age. They need the hormones from puberty to fully grow and develop properly.
With all the contradictory information being shared, how can we meet in the middle? Modified spay and neuter procedures such as an ovary-sparing spay or vasectomy protects the dog’s hormones while preventing pregnancy. However, these procedures are relatively uncommon and are not performed by all veterinarians. Pet owners must do their research to determine what options are available to them and decide what is in the best interest of their dog. Based on the current information available, delaying sterilization until a dog has fully matured has the greatest benefit with the least risk compared to an early spay.
Pet owners may choose to x-ray their dogs to ensure that their growth plates are fully closed before sterilization to prevent abnormal growth and development. Pictured above are two littermates at 10 months of age. The puppy on the left was spayed at 5 months of age and the puppy on the right is intact. The puppy that was spayed prematurely has longer legs, a leaner build, and less developed skull. The intact puppy has a more proportionate build and his appearance is closer to breed standard.
In conclusion, pet owners need to be aware of all variables and factors involved in sterilization. Spay and neuter affects dogs medically, behaviorally, and developmentally. Whether or not you spay or neuter and at what age can have lifelong implications for your pet. Pet owners that adopt a sterile puppy from a rescue should be aware of the potential effects of an early spay or neuter. Sterilization is a decision that can’t be taken back so it’s imperative that dog owners be aware of all potential risks and benefits of the procedure before making the decision for their pet.