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Neutering of Dogs and Cats Controversy

By February 7, 2019 February 23rd, 2019 Uncategorized

Recently the has been a lot of controversy surrounding early spay-neuter status in dogs (primarily) and cats. Unfortunately, veterinarians do not have all the answers yet. However, it is important to discuss the issues surrounding sterilization procedures with owners so that they may make an informed decision.
This is the current Position Statement from the CVMA on the issue:
The Canadian Veterinary Medical Association (CVMA) strongly recommends that all cats and dogs which are not part of a responsible breeding program be neutered before sexual maturity, except when there is scientifically justifiable health or behavioural benefits that might be gained by delaying the procedure.


  • The CVMA believes that neutering (spaying of females or castration of males) is an important aspect of responsible pet care because it helps to combat dog and cat overpopulation.
  • Neutering dogs and cats also has health and behavioural benefits, such as reduced risk of diseases and undesirable behaviours that are influenced by reproductive hormones.
  • An owner’s decision to neuter, including when to neuter their pet, should be made in consultation with a licensed veterinarian after an assessment of each patient.
  • The CVMA advocates for pre-pubertal neutering of cats and dogs, except when there are valid evidence-based reasons to delay the procedure.
  • The CVMA supports neutering of dogs and cats prior to adoption from animal shelters.


  1. Neutering is defined in this document as the surgical removal of gonads (testicles or ovaries, which usually also includes removal of the uterus) in both male and female dogs and cats. It is a method of contraception and has the added benefit of aiding in the prevention of diseases of the reproductive system (1). All neutering procedures must adhere to sound veterinary surgical and aseptic technique with adequate pain control to minimize complications (2).
  1. The CVMA supports all educational efforts to promote responsible pet ownership. Neutering companion animals is part of being a responsible owner.
  1. Early neutering reduces the incidence of reproductive hormone dependent diseases, reduces surgical complication rates, and shortens recovery and healing times (3,4). Research shows a significant reduction in mammary gland tumours in female dogs and cats neutered prior to sexual maturity (3-5).
  1. The benefits of early neutering of male cats include preventing the birth of more kittens that contribute to the cat overpopulation crisis, as well as reduced urine marking, and some forms of aggressive behaviour (5,6). Reproductive hormone influenced behaviours of male cats, such as urine spraying, makes them undesirable as household pets, and is a common reason for relinquishment to shelters (3).
  1. For male dogs, in addition to preventing unwanted pregnancies, neutering reduces certain undesirable behaviours such as status-related aggression, urine marking, mounting, and roaming (3,7). Neutering male dogs can also prevent most types of prostate disease (e.g., hyperplasia and prostatitis), with the exception of prostate cancers and paraprostatic cysts (8).
  1. There are some studies suggesting a negative impact from early neutering. These studies may implicate certain bone developmental abnormalities, urinary sphincter incontinence, cancers, and undesirable behaviours in some large and giant dog breeds, particularly when neutered before full maturity (9-12). More research is required to explore these issues, as current data are conflicting, few breeds have been investigated, and most are retrospective studies. Longitudinal and case control studies are lacking.
  1. The CVMA strongly supports neutering of cats and dogs at animal shelters prior to adoption, including early neutering, to prevent ongoing contributions to pet overpopulation issues. Low compliance rates have been reported for post-adoption spay and neuter shelter programs (4). The rate of owner relinquishment increases for sexually intact dogs and cats (4,13).
  1. Vasectomy and tubal ligation result in contraception, but do not remove the gonads. These are surgical procedures with no additional benefit to the animal to prevent reproductive hormone dependent diseases, as hormones are still produced. These techniques also do not have the added benefit of preventing undesirable reproductive hormone dependent behaviours (e.g., status-related aggression, urine marking, mounting, and roaming). Thus, these surgeries are not commonly performed by veterinarians, nor recommended by the CVMA.
  1. The CVMA supports research into safe and efficacious nonsurgical methods of sterilization. However, preliminary research into immunocontraception (i.e., vaccination), chemical castration (e.g., zinc and calcium chloride neutering), and hormonal (e.g., GnRH) treatments has not yielded a consistently safe, efficacious, and marketable approved product for clinical use (14-16).