An excellent article by Kendall E. Houlihan DVM with the Animal Welfare Division of the American Veterinary Medical Association (AVMA) entitled “ A literature review on the welfare implications of gonadectomy of dogs” was published in the Journal of the AVMA, May 10, 2017. In summary, aside from the sound policy of neutering all shelter dogs and pups with rare exception as a population control measure, exceptions may be indicated for dog owners not in the business of breeding dogs.
These exceptions, where dogs of certain breeds, size and sex may have greater health benefits from not being gonadectomized/ neutered after informed veterinary assessment, are considerable. Thanks to Dr. Houlihan, veterinarians can now better inform their clients with certain pure breeds such as those susceptible to bone cancer, about the pros and cons of neutering, and after determining the clients’ competence in handling non-neutered dogs. While neutering may increase the risk for other cancers in certain breeds and sexes such as of the urinary bladder, cutaneous mast cell tumors and hemangiosarcomas, overall it increases longevity. Lymphomas seem to be least prevalent in un-neutered female dogs. Neutered male and female dogs are twice as likely as non-neutered dogs to develop bone cancer. Neutering eliminates the possibility of cancers of the reproductive organs, reduces of breast/mammary cancer especially if done before the first heat and reduce the incidence of benign prostatic hyperplasia. Neutered dogs of both sexes are more prone to cruciate (knee) ligament rupture, which may be associated with susceptibility to obesity, while hip dysplasia is more prevalent in neutered males than in neutered and intact females. Aggression between male dogs is more prevalent when they are not neutered. Urinary incontinence is most often seen in neutered females but can generally be controlled with medication.
Clearly, neutering has many health and welfare benefits for dogs kept as companions, but there are exceptions that are worth careful consideration by both veterinarians and their dog-owning clients. As Dr. Kendall states in a personal communication ( 6/6/17) “As research into potential impacts is ongoing, veterinarians should continue to use their professional judgment, weighing all of this information in light of the individual animal’s ownership, breed, sex, and intended use. The low incidence and multi-factorial nature of many of these conditions make it unlikely that recommendations for routine spay and neuter practices will be substantially altered”.
However, there are cultural considerations also, neutering being discouraged in Scandinavian countries with a reported 7 per cent of dogs being neutered. The Norwegian Animal Welfare Act makes it clear that surgical procedures are not to be used to adapt animals to the needs of humans unless strictly necessary.
NEW DATA
I urge all veterinarians and people with young dogs of certain breeds who are not yet neutered to read this latest review that states:
“Spaying female and castrating male dogs, hereinafter referred to as neutering, is a US convention for the first year in the dog’s life. Research on 35 breeds of dogs revealed that early neutering increases risks of joint disorders, such as hip dysplasia (HD), elbow dysplasia (ED), or cranial cruciate ligament (CCL) tear, or cancers, such as lymphosarcoma (LSA), mast cell tumor (MCT), hemangiosarcoma (has), or osteosarcoma (OSA), for some breeds. Joint disorder risks are heightened for some larger breeds and for mixed-breed dogs weighing more than 20 kg. Some breeds had elevated risks for cancers.” - Hart, L.A. et al Assisting decision-making on age of neutering for German Short/Wirehaired Pointer, Mastiff, Newfoundland, Rhodesian Ridgeback, Siberian Husky: associated joint disorders, cancers, and urinary incontinence. Front. Vet. Sci., 12 April 2024. Sec. Animal Reproduction – Theriogenology Volume 11 - 2024 | https://doi.org/10.3389/fvets.2024.1322276
Neutering at an early age is an issue with animal shelters where the policy is early spay/castrate all pups prior to adoption. That should be revised with the new findings of adverse consequences in certain breeds since mixed breeds may also be adversely affected later in life. One option for shelters is to vasectomize male pups and perform hysterectomies on females, leaving the ovaries intact. Testicles and ovaries can be removed later in life after veterinary consultation. Urinary incontinence, for example,which may lead some owners to put their dogs up for adoption, would be avoided especially in young female dogs spayed at a young age.