Vasectomy and ovary-sparing spay in dogs: comparison of health and behavior outcomes with gonadectomized and sexually intact dogs

summary of:
Vasectomy and ovary-sparing spay in dogs: comparison of health and behavior outcomes with gonadectomized and sexually intact dogs
dogs lying in a field
Zink, C., Delgado, M. M. and Stella, J. L.
Published in:
January 2023
Type of access:

Open access

In our edition of: Apr 2023
In our categories of: small animals

our summary:

Zink, C., Delgado, M. M., and Stella, J. L. (2023) Vasectomy and ovary-sparing spay in dogs: comparison of health and behavior outcomes with gonadectomized and sexually intact dogs. Journal of the American Veterinary Medical Association, 261 (3), pp. 366-374

The aim of this online survey study was to compare the health and behaviour outcomes for dogs that underwent vasectomy (VS), or ovary-sparing spay (hysterectomy) (OSS) with sexually intact dogs or dogs that had undergone traditional castration or spay (ovariohysterectomy or ovariectomy). The authors hypothesised that dogs that received a VS or OSS would have similar health and behavioural profiles to those of sexually intact dogs because of the retention of gonadal hormones.

The survey, which initially ran from 3rd November 2021 to 14th December 2021 , recruited participants via the newsletter and social media channels of an American organization that promotes responsible dog breeding. The survey collected basic demographic data about the participant and information on their dog including breed, weight, age and reproductive status. The options for reproductive status were sexually intact, castrated, spayed (ovariohysterectomy or ovariectomy), vasectomy, or ovary-sparing spay (hysterectomy). Further questions captured data  on the dog’s orthopaedic health, diagnoses of cancer and other health problems (e.g. obesity) and about two types of behaviour problems:  problematic behaviour (includ­ing aggression, anxiety-based behaviours, and ex­treme fears) and nuisance behaviours (e.g. urine marking and mounting behaviour). The survey continued to collect information from VS and OSS dogs until 7th January 2022 to increase the numbers.

A total of 6,018 valid responses were received representing 3,753 dogs that were alive at the time of the survey and 2,265 dogs that were deceased. The data set included 1,056 sexually intact, 1,672 castrated, and 58 vasectomized males and 792 sexually intact, 2,281 spayed, and 159 females that had undergone an OSS. Analysis showed that longer duration exposure to gonadal hormones, regardless of reproductive status, was associated with reduced odds of general health problems and both nuisance and problematic behaviours. The rate of some health conditions, such as orthopaedic conditions and cancer, increased in gonadectomised dogs.

Limitations of the study are the small number of dogs that had undergone VS or OSS, the low prevalence of reported health conditions, potential selection bias with many respondents linked to a dog breeding organisation and recall bias due to the retrospective nature of the study. The data may also have been affected by cause-and-effect e.g. dogs may have been spayed or neutered because of health issues and some of the health problems examined may have been a typical part of aging. It should also be noted that there were significant differences in the mean ages of the groups of dogs, which may have impacted the relative prevalence of the health problems reported. Full details of the data collected are available in the supplementary materials.

Take Home

This study provides some evidence on the health and behaviour outcomes of vasectomy and ovary-sparing spay in dogs.  Further studies are encouraged as increasing the evidence base will assist veterinary surgeons when discussing the risks and benefits of the various surgical options.

The following may also be of interest:

inFOCUS: Benefits and risks of neutering pets – what is the evidence [RCVS Knowledge] [online] Available from: [Accessed 22 April 2023]

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