by Teresa Garden, DVM
For decades the answer to this question has been a resounding YES! Veterinarians have recommended the sterilization procedure across-the-board regardless of age or breed and the public complied. However, recent research studies are pointing out adverse consequences of neutering and leading some veterinarians to believe more thought and consideration should be given to the topic. In this article we will discuss the pros and cons of neutering male dogs. (Our next article will focus on spaying female dogs).
Most of us are familiar with the benefits of neutering male dogs. Once the testicles have been surgically removed, a male dog cannot impregnate female dogs. This can prevent pet over-population and unwanted pregnancies. Neutering will decrease aggression and roaming behavior. Without testosterone, there is a much less chance a male dog will “mark” his surroundings. No one wants Bruiser hiking his leg and urinating on beautiful drapes and expensive furniture. All of these factors lead to a more practical pet.
There are a few health benefits associated with neutering. A study conducted at the University of Georgia showed neutering increased life expectancy by 13.8%. Sterilization offered protection against pathological processes including infections and trauma. Neutering eliminates the risk (although very small) of dying from testicular cancer. It decreases the risk of benign prostatic hyperplasia and perineal fistulas. Neutering is definitely advised for dogs born with undescended testicle(s) since they have a 13 times higher risk factor of developing testicular cancer in the undescended testicle(s).
Recent retrospective epidemiological studies and forward-looking research studies have uncovered possible adverse effects of neutering. The following data are from studies published in February 2013 from the University of Georgia and the University of California-Davis. Early neutering (performed at less than 1 year of age) increased the risk of osteosarcoma in medium, large and giant breeds of dogs. The risk factor was 2 times higher in neutered males compared to intact males. In Rottweilers the risk factor was 3 times higher. The sex hormones are known to influence maintenance of skeletal structure and mass. Early neutering showed a 4 times higher risk factor in developing prostate cancer. It is postulated testicular hormones may protect against this type of cancer. Golden Retrievers, Akitas, and Great Danes showed a 3 times increased risk of developing hypothyroidism vs intact males of the same breeds. A lack of sex hormones may decrease protection against autoimmune thyroiditis. Neutered males showed an increased risk of developing cancers such as lymphoma and hemangiosarcoma.
Neutering can also play a role in whether your pet has an increased risk of certain orthopedic disorders. Neutering before 5 1/2 months old was associated with 70% increase in age-adjusted risk of hip dysplasia compared to dogs neutered after 5 1/2 months of age. Ten percent of dogs neutered before 12 months of age were diagnosed with hip dysplasia compared to 5% seen in intact males of the same breed. Neutered dogs showed a 2 times higher risk for cranial cruciate ligament rupture and a 3 times higher risk of patellar luxation compared to intact males.
Neutered dogs are 3 times more likely to be overweight than intact males due to changes in metabolism. Becoming obese then leads to increased risk of other diseases such as diabetes, hyperadrenocorticism, cancer, pancreatitis, and hypothyroidism. Adverse vaccine reactions were 27% more likely to occur in neutered males vs intact males in small and toy breeds. Sex hormones may play a role in the body’s ability to mount a proper immune response to vaccination.
So what conclusions can we draw from all this data? Overall, it appears there are no compelling medical reasons to neuter most male dogs. Health problems associated with neutering exceed benefits in most cases. However, the issue of pet overpopulation and the beneficial effects on behavior cannot be overlooked when considering the decision to neuter. It certainly seems prudent not to neuter medium, large, and giant breeds of dogs until they are physically mature. This will at least help to avoid the increased risk of serious orthopedic problems such as hip dysplasia. Delaying neutering until these breeds are mature will also negate the increased risk to cancers such as osteosarcoma, lymphoma, and hemangiosarcoma. The decision to neuter should be based on each individual pet taking into account the dog’s age, breed, temperament, training, and life style. An educated pet owner can then make an informed decision whether or not to neuter their own male dog.
The above discussion is by no means meant to be a criticism of the early spay/neuter programs conducted by our local animal shelters. These programs are a necessity to prevent pet overpopulation and to help ensure increased adoptions of unwanted dogs and cats. I dedicated a significant proportion of my professional career working for the Humane Society of Missouri and still strongly believe in and support their mission.
Dr. Teresa Garden is chief veterinarian/owner of Animal Health & Healing, a full-service holistic and conventional veterinary practice in the Maplewood/Richmond Heights area. AnimalHealthandHealing.com; phone: 314-781-1738.