Position Statements

Spaying and Neutering of Dogs and Cats

December 11, 2024

Position statements developed by the CVMA reflect current knowledge regarding animal welfare. While they are not legislative, they do represent CVMA’s ongoing commitment to the advancement of animal welfare.

Position

The Canadian Veterinary Medical Association (CVMA) strongly recommends that cats and dogs
not intended for breeding be spayed or neutered. It is best practice that all sheltered animals
should be spayed or neutered prior to adoption whenever possible.

Summary

  • The CVMA supports all efforts to prevent unplanned breeding (including spaying or
    neutering of companion animals by licensed veterinarians) and recognizes this is an
    integral part of pet ownership.
  • Spaying or neutering dogs and cats can provide health and behavioural benefits such
    as reduced risk of some diseases and undesirable behaviours that are influenced by
    reproductive hormones.
  • The CVMA advocates for pre-pubertal spaying or neutering of all sheltered dogs and
    cats, which is critical for addressing the serious concern of pet overpopulation in
    Canada.
  • Pet owners should consult a licensed veterinarian when deciding timing of spay or
    neuter surgery for an assessment of the risks and benefits given their pet’s breed, size,
    behavioural characteristics, and planned use of the pet.
  • The current veterinary professional workforce shortage may affect accessibility of spay
    and neuter procedures.
  • The CVMA advocates for further research into the ideal timing of spaying and
    neutering of cats and dogs, along with non-surgical alternative procedures.

Background

  1. The CVMA supports spaying and neutering of dogs and cats prior to adoption from animal shelters.
  2. Spaying and neutering involves the surgical removal of the gonads (testicles or ovaries and/or uterus) in both male and female dogs and cats. These are methods of contraception that reduce the production of sex hormones and have the added benefit of aiding in the prevention of diseases of the reproductive system. Neutering is defined in this document as the surgical removal of the testicles. Spaying is defined in this document as removal of the uterus and ovaries (ovariohysterectomy) or removal of the ovaries while leaving the uterus in place (ovariectomy); in both procedures it is important to ensure all ovarian tissue is removed (1).
  3. Other less common techniques for prevention of pregnancy include procedures that do not remove the gonads. Animals undergoing these procedures will have the same reproductive hormones as intact animals, and female dogs will still have estrus (heat) cycles. Reproductive hormone disease risk will also remain the same as intact animals, and these procedures also do not have the added benefit of preventing undesirable reproductive hormone dependent behaviours (e.g. estrus (heat) cycles, urine marking, mounting, and roaming) (1).
    a. Hysterectomy: removal of the uterus
    b. Tubal ligation: transection or blockage of the fallopian tubes
    c. Vasectomy: ligation of the spermatic cords
  4. The CVMA holds that spaying and surgical neutering of dogs and cats are veterinary procedures and as such, must be performed by a licensed veterinarian or a suitably supervised veterinary student in accordance with regulations of the provincial/territorial jurisdictions. All procedures must adhere to sound veterinary surgical and aseptic technique with adequate pain control to minimize complications (2).
  5. Pet overpopulation is an ongoing serious concern that can be significantly addressed by spaying and neutering (3,4). Prevention of unplanned breeding is essential to controlling pet overpopulation and is an integral part of pet ownership. Access to veterinary care can be limited by factors such as geography and/or financial concerns. (5). The CVMA supports all efforts to improve access to veterinary services including preventive care such as spaying and neutering.
  6. Low compliance rates have been reported for post-adoption spay and neuter shelter programs (6). The CVMA strongly supports spaying and neutering of all cats and dogs regardless of age at animal shelters prior to adoption.
  7. As there are potential risks and benefits to spaying and neutering of dogs and cats, the decision on when to perform these procedures on homed pets should be undertaken after consultation with a veterinarian. Factors such as access to care, cost, ability to manage an intact animal to prevent unwanted breeding, and tolerance for behaviours associated with intact animals (estrus cycles, marking behaviours etc.) should be discussed and considered (6,7). Timing of the surgery should always consider the benefit to the animal, while taking into consideration the pet’s home life.
  8. Recent research appears to support potential negative impacts from pre-pubertal spaying and neutering in large breed dogs. Studies suggest a correlation between increased risk of bone developmental abnormalities, urinary sphincter incontinence, some neoplasias, obesity, and undesirable behaviours in some large and giant breed dogs, particularly when neutered before full maturity (8-13). The development of these conditions is multifactorial in nature and research is active and ongoing in this area.
  9. Most cats not intended for breeding should be spayed or neutered by 5 months of age
    (14) in order to prevent unwanted pregnancies.
    a. Pre-pubertal neutering of male cats prevents the birth of more kittens that contribute to the cat overpopulation crisis, as well as reduces urine marking and some forms of aggressive behaviour (15,16). Pre-pubertal neutering in cats has not been shown to increase risks of urinary obstruction (17,18). 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 (7).
    b. Spaying female cats reduces the incidence of reproductive hormone dependent diseases, prevents pyometra and other uterine or ovarian diseases, and prevents estrus behaviours such as vocalization and roaming (15,16). When performed prior to sexual maturity, spaying can also reduce the occurrence of mammary gland tumours (19).
  10. Spaying and neutering dogs has been shown to provide some health benefits in addition to prevention of unwanted pregnancies.
    a. Neutering male dogs can reduce certain undesirable behaviours such as urine marking, mounting, and roaming (7,20). Prevention of breeding attempts also reduces the rate of transmissible venereal tumors and other sexually transmitted pathogens such as Brucellosis (21, 22). Most types of prostate disease can also be prevented (e.g., hyperplasia and prostatitis) with the exception of prostate cancers and paraprostatic cysts (23).
    b. Spaying female dogs prior to sexual maturity can reduce the incidence of reproductive hormone dependent diseases, reduce surgical complication rates and often costs, and shorten recovery and healing times. Most research appears to support reduction in mammary gland tumours in female dogs when spayed (with ovarian removal) prior to 2-3 years of age (24, 25, 26). Spaying also prevents pyometra and other uterine or ovarian diseases when the ovaries are fully removed (27).
  11. The CVMA supports research into safe and efficacious nonsurgical methods of contraception. Products involving hormonal contraception (deslorelin acetate) are entering the market, and research into immunocontraception (i.e. vaccination), chemical castration (i.e., zinc and calcium chloride neutering) continue and may provide acceptable options in the near future (28-30).

References

  1. Howe LM. Surgical methods of contraception and sterilization. Theriogenology 2016;66:500-509. https://www.ncbi.nlm.nih.gov/pubmed/16716381 Last accessed September 11, 2024.
  2. CVMA Veterinary Surgical Procedures Performed on Animals – Position Statement. January 22, 2021 . https://www.canadianveterinarians.net/policy-and-outreach/position-statements/statements/surgical-procedures-performed-on-animals. Last accessed September 11, 2024
  3. Humane Canada 2021 Animal Shelter Statistics. https://humanecanada.ca/en/your-humane-canada/news-and-reports/reports/2021-canadian-animal-shelter-statistics-report. Last accessed September 11, 2024.
  4. Humane Canada. Position Statement on Spaying and Neutering. https://humanecanada.ca/en/about-us/position-statements. Last accessed September 11, 2024.
  5. Jacobson LS, Kyrsten J, Janke KJ, Probyn-Smith K, Stiefelmeyer K. Barriers and Lack of Access to Veterinary Care in Canada 2022. Journal of Shelter Medicine and Community Animal Health 2024. Barriers and Lack of Access to Veterinary Care in Canada 2022 | Journal of Shelter Medicine and Community Animal Health (jsmcah.org). Last accessed September 11, 2024.
  6. Bushby PA, Griffin B. Veterinary medicine: An overview of pediatric spay and neuter benefits and techniques. dvm360 February 2011. Available
    from: https://www.dvm360.com/view/overview-pediatric-spay-and-neuter-benefits-and-techniques Last accessed September 11, 2024.
  7. Root Kustritz MV. Determining the optimal age for gonadectomy of dogs and cats. J Am Vet Med Assoc 2007;231:1665-1675. https://www.ncbi.nlm.nih.gov/pubmed/18052800 Last accessed September 11, 2024.
  8. Hart BL, Hart LA, Thigpen AP, Willits NH. Neutering of German Shepherd Dogs: Associated joint disorders, cancers and urinary incontinence. Veterinary Medicine and Science 2016;2:191-199. Available
    from: https://onlinelibrary.wiley.com/doi/full/10.1002/vms3.34 Last accessed September 11, 2024.
  9. Hart BL, Hart LA, Thigpen AP, Willits NH. Long-term health effects of neutering dogs: Comparison of Labrador retrievers with golden retrievers. PLoS ONE 2014;9:e102241. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25020045 Last accessed September 11, 2024.
  10. Duffy DL, Serpell JA. Non-reproductive effects of spaying and neutering on behavior in dogs. AAC&D 3rd International Symposium on Non-Surgical Contraceptive Methods for Pet Population Control. Alexandria, Virginia. November 2006. https://www.naiaonline.org/uploads/WhitePapers/EarlySNAndBehaviorDuffySerpell.pdf Last accessed September 11, 2024
  11. Hart LA, Hart BL, Thigpen AP. Decision-Making on Recommended Age of Spay/ Neuter for a Specific Dog General Principles and Cultural Complexities. 2023. Vet Clin Small Anim 53 1209–1221. https://pubmed.ncbi.nlm.nih.gov/37330274/ Last accessed September 11, 2024.
  12. Hart BL, Hart LA, Thigpen, AP, Willits, NH. Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated joint Disorders, Cancers, and Urinary Incontinence. Front. Vet. Science. 2020 Vol 7. https://www.frontiersin.org/articles/10.3389/fvets.2020.00388/. Last accessed September 11, 2024.
  13. Benka VA, Scarlett JM, Sahrmann J, Rieke JK, Briggs JR, Ruple A, Zawistowski S Morrison JA, Spofford N, Romagnoli S. Age at gonadectomy, sex, and breed size affect risk of canine overweight and obese outcomes: a retrospective cohort study using data from United States primary care veterinary clinics. J. American Vet Med Assoc 2023 261 (9): Vol 1316-1325. https://avmajournals.avma.org/configurable/content/journals$002fjavma$002f261$002f9$002fjavma.22.12.0596.xml?t:ac=journals%24002fjavma%24002f261%24002f9%24002fjavma.22.12.0596.xml Last accessed September 11, 2024
  14. Veterinary Task Force on Feline Sterilization. Recommendations for Age of Spay and Neuter Surgery. https://catvets.com/resource/feline-sterilization-for-age-of-spay-and-neuter-surgery-endorsement/. Last accessed September 11, 2024.
  15. Howe LM, Slater MR, Boothe HW, et al. Long-term outcome of gonadectomy performed at an early age or traditional age in cats. J Am Vet Med Assoc 2000;217:1661-1665. Available from:
    https://www.ncbi.nlm.nih.gov/pubmed/11110455 Last accessed September 11, 2024.
  16. Spain CV, Scarlett JM, Houpt KA. Long-term risks and benefits of early-age gonadectomy in cats. J Am Vet Med Assoc 2004;224:372-379. https://www.ncbi.nlm.nih.gov/pubmed/14765796 Last accessed September 11, 2024.
  17. Root MV, Johnston SD, Johnston GR, Olson, PN. The Effect of Prepuberal and Postpuberal Gonadectomy On Penile Extrusion And Urethral Diameter In The Domestic Cat. 1996. Vet Radiol Ultrasound. 37(5):363-366. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1740-8261.1996.tb01244.x?msockid=0800507e4cfa60ed37e344d54d2c61cf Last accessed September 11, 2024
  18. de Oliveira Sampaio K, Amaro da Silva Junior V , Pereira de Sousa-Filho R, Anahy de Sousa Aleixo G, Marina Gabriela Monteiro Carvalho Mori da Cunha M 3, Ellen Cordeiro Bento da Silva. Neutering is not associated with early-onset urethral obstruction in cats. J Feline Med Surg. December 2022;24(12):e611 - e617. https://pubmed.ncbi.nlm.nih.gov/36453601/ Last accessed September 11, 2024.
  19. Overley B, Shofer FS, Goldschmidt MH, et al. Association between ovariohysterectomy and feline mammary carcinoma. 2005. J Vet Intern Med19,560–563. https://pubmed.ncbi.nlm.nih.gov/16095174/ Last accessed September 11, 2024.
  20. Neilson JC, Eckstein RA, Hart BL. Effects of castration on problem behaviors in male dogs with reference to age and duration of behavior. J Am Vet Med Assoc 1997;211:180-182. Available from: https://www.ncbi.nlm.nih.gov/pubmed/9227747 Last accessed September 11, 2024.
  21. Kaufman LK, Peterson, CK. Canine Brucellosis Old Foe and Redeeming Scourge. Veterinary Clinical of North America-Small Animal Practice. July 2019 49(4) pp 763-788. https://pubmed.ncbi.nlm.nih.gov/30961996/ Last accessed September 11, 2024.
  22. Strakova A, Murchison EP. The changing global distribution and prevalence of canine transmissible venereal tumour. BMC Veterinary Research 2014 September 03 Vol 10 p 168. https://pubmed.ncbi.nlm.nih.gov/25186078/ Last accessed September 11, 2024.
  23. Kutzler MA. Prostatic disease. In: Monnet E, ed. Small Animal Soft Tissue Surgery.
    Chichester, UK: John Wiley & Sons, 2012. https://onlinelibrary.wiley.com/doi/10.1002/9781118997505.ch66 Last accessed September 11, 2024.
  24. Association of Shelter Veterinarians Position Statement. Early Age Spay Neuter. May 2020. https://higherlogicdownload.s3.amazonaws.com/ASV/fa11b6a5-ea22-45cc-9b33-416a24d44499/UploadedImages/Policy_Stmts/Early_Age_SN.pdf Last accessed September 11, 2024.
  25. Beauvais W, Cardwell JM, Brodbelt DC. The effect of neutering on the risk of mammary tumours in dogs–a systematic review. 2012. J Small Animal Practice 53,314–322.
    https://pubmed.ncbi.nlm.nih.gov/22647210/ Last accessed September 11, 2024.
  26. Gedon J, Wehrend A, Kessler M. Ovariectomy reduces the risk of tumour development and influences the histologic continuum in canine mammary tumours. Veterinary & Comparative Oncology; Jun 2022, Vol. 20 Issue 2, p476-483. https://pubmed.ncbi.nlm.nih.gov/34913241/ Last accessed September 11, 2024.
  27. van Goethem, B, Schaefers-Okkens A, Kirpensteijn J. Making a rational choice between ovariectomy and ovariohysterectomy in the dog: a discussion of the benefits of either technique. Vet Surg 2006 Feb;35(2):136-43. https://pubmed.ncbi.nlm.nih.gov/16472293/ Last accessed September 11, 2024.
  28. Kutzler M, Wood A. Non-surgical methods of contraception and sterilization.
    Theriogenology 2006;66:514-525. https://www.ncbi.nlm.nih.gov/pubmed/16757019 Last accessed September 11, 2024.
  29. Root Kustritz MV. Nonsurgical contraceptives for dogs and cats (Proceedings). dvm360 May 2011. Available from: https://www.dvm360.com/view/nonsurgical-contraceptives-dogs-and-cats-proceedings Last accessed September 11, 2024.
  30. Parsemus Foundation. Calcium chloride nonsurgical sterilization: Bibliography. https://www.parsemus.org/wp-content/uploads/2020/11/Calcium-Chloride-BIBLIOGRAPHY-_rev8-5-20.pdf Last accessed September 11, 2024.