Castration of Piglets
May 24, 2023
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.
The Canadian Veterinary Medical Association (CVMA) holds that surgical castration of piglets to prevent boar-taint (an unpleasant odor and flavour in pork) and aggression in post- pubertal boars is a painful procedure at any age and an effective pain mitigation protocol is necessary for all ages of pigs. The CVMA encourages development and implementation of practical analgesic and anesthetic protocols for swine castration and production chain evolution to support adoption of immunocastration and marketing of intact boars.
- Castration of piglets is used to help avoid unwanted behaviour and prevent meat quality issues in pork.
- Castration is a painful procedure.
- Effective pain management involving analgesia and/or anesthesia is required.
- Lack of access to effective, approved drugs for pain control is a barrier to improving animal welfare and needs to be improved.
- Veterinarians should provide producer training, including appropriate anesthesia/analgesia.
- Alternatives to surgical castration exist.
- 1. In North America, hogs are marketed between 5 and 6 months of age at approximately 120 kg live weight (265 lb). Intact market weight boars are post- pubescent. Sexual activity and aggression from intact boars can cause injury, pain, and discomfort. Castration of piglets is a method of avoiding unwanted post-pubertal behaviour and controlling boar taint, an unpleasant odour and flavour of cooked pork.
- While surgical castration falls under the CVMA definition of surgery (1), and as such should be done by a veterinarian or a registered veterinary technician under the supervision of a veterinarian, CVMA recognizes that the procedure is often done by producers. Therefore, under the current practices, CVMA holds that veterinarians, under a valid Veterinarian-Client-Patient-Relationship (VCPR), should provide training to producers on the recognition and treatment of pain, cryptorchidism and herniation, appropriate handling, routine castration techniques, post castration management as well as anesthetic and analgesia protocols to follow when undertaking castration.
- This surgical procedure is acutely painful and involves the incision of skin and manipulation of sensitive tissues with subsequent inflammation (2-5). There is a risk of hemorrhage, infection, and evisceration (6).
- Local anesthetic injected into the testes and subcutaneously into the scrotum reaches the spermatic cord within minutes (7) and can reduce some of the responses to castration (8-10) although there is evidence that the process of injection causes pain (11). Post-castration pain can last for 2 days (12).
- Age does not impact an animal's response to pain (13, 14) however there are risks and limitations associated with anesthesia in very young animals (11). The current National Farm Animal Care Council Code of Practice for the Care and Handling of Pigs (2014) for producers requires the administration of analgesia for castration at all ages, but only requires anesthesia and analgesia for piglets older than 10 days of age (15).
- Some non-steroidal anti-inflammatory drugs (NSAIDS) have been approved for use in piglets in Canada and can reduce some post-operative pain responses (14, 16, 17). Research continues to evolve on the beneficial effects of NSAIDS in pigs (18). The CVMA supports continued research to clarify the benefits of use in pigs.
- The administration of local anesthesia requires restraint, additional handling, and a time delay for the anesthetic to take effect as compared to the use of analgesia alone. (19, 20). Although the strength of the evidence has been questioned (21, 22, 23) and there is stress associated with extra handling and the administration of the local anesthetic (3), the administration of both local anesthesia and analgesia is encouraged to effectively reduce the pain response during and after surgical castration (10, 22, 24, 25).
- Alternatives to surgical castration exist, including immunocastration (20) and sending of intact male pigs to slaughter prior to sexual maturation. These strategies are successfully used in the European Union but require cooperation throughout the supply chain.
- The CVMA recognizes that there is an urgent need to develop and approve anesthetic and analgesic drugs for swine, and to provide veterinarians and producers with appropriate withdrawal times for these drugs (26). Currently, some anesthetic and analgesic drugs are licensed for use in companion animals, but fewer are licensed for use in swine. Lack of availability and efficacy of licensed veterinary drugs for anesthesia and analgesia may be a barrier to improvement of pig welfare during castration. To further improve pain management in swine, CVMA encourages Canadian regulators and producers to review procedures and outcomes in countries where licensed products exist to expand the repertoire of pain control measures available in swine.
- The CVMA supports quality assurance programs that promote humane treatment of all species through the prudent use of extra-label anesthetic and analgesic drugs. Given the current lack of anesthetic and analgesic drugs licensed for use in swine, the CVMA supports the responsible extra-label use of these drugs by veterinarians (27). Additional information can be found on the CVMA Position Statement on Extra- label Drug Use (28).
- The CVMA also urges federal regulators to develop programs that facilitate approval of swine-appropriate anesthetic and analgesic drugs in order to reduce unnecessary animal pain.
- CVMA Position Statement on Surgical Procedures Performed on Animals https://www.canadianveterinarians.net/policy-and-outreach/position- statements/statements/surgical-procedures-performed-on-animals/
- Taylor AA, Weary Vocal responses of piglets to castration: Identifying procedural sources of pain. Appl Anim Behav Sci 2000;70:17-26. https://pubmed.ncbi.nlm.nih.gov/10986420/
- von Borell E, Baumgartner J, Giersing M, et Animal welfare implications of surgical castration and its alternatives in pigs. Animal 2009;3:1488-1496. https://pubmed.ncbi.nlm.nih.gov/22444982/
- Rault J, Lay DC,Jr., Marchant-Forde Castration induced pain in pigs and other livestock. Appl Anim Behav Sci 2011;135:214-225. https://pubag.nal.usda.gov/catalog/53886
- Schmid S.M. Genter CI et al. 2021. Impact of tearing spermatic cords during castration in live and dead piglets and consequences on welfare. Porcine Health Management 7.17. https://porcinehealthmanagement.biomedcentral.com/articles/10.1186/s40813-021- 00200-7
- St Jean Male reproductive surgery. The Veterinary Clinics of North America. Food animal practice. 1995;11:55-93. https://pubmed.ncbi.nlm.nih.gov/7796336/
- Ranheim B, Haga HA, Ingebrigtsen Distribution of radioactive lidocaine injected into the testes in piglets. J Vet Pharmacol Ther 2005;28:481-483. https://pubmed.ncbi.nlm.nih.gov/16207312/
- McGlone JJ, Hellman JM. Local and general anesthetic effects on behavior and performance of two- and seven-week-old castrated and uncastrated J Anim Sci 1988;66:3049-3058. https://academic.oup.com/jas/article- abstract/66/12/3049/4695808?login=false
- Kluivers-Poodt M, Houx BB, Robben SRM, Koop G, Lambooij E, Hellebrekers LJ. Effects of a local anaesthetic and NSAID in castration of piglets, on the acute pain responses, growth and mortality. Animal 2012;6:1469-1475. https://pubmed.ncbi.nlm.nih.gov/23031520/
- Sheil ML, Chambers M and Sharpe Topical Wound Anesthesia: Efficacy to mitigate piglet castration pain. Aus Vet Journ, 2020; 98:6:256-263. https://pubmed.ncbi.nlm.nih.gov/32096229/
- Saller A, Werner, J., Reiser, J., Senf, S., Deffner, P., Abendscho, N., Wei, C.,Fischer, , Schowerth, A., Miller, R., Zablotski, Y., Bergmann, S., Erhard, MH., Ritzmann, M., Zois, S., Baumgartner, C. Local anesthesia in piglets undergoing castration—A comparative study to investigate the analgesic effects of four local anesthetics on the basis of acute physiological responses and limb movements. Plos One, 2020. https://pubmed.ncbi.nlm.nih.gov/32730302
- Hay M, Vulin A, Génin S, Sales P, Prunier A. Assessment of pain induced by castration in piglets: Behavioral and physiological responses over the subsequent 5 Appl Anim Behav Sci 2003;82:201-218. https://www.researchgate.net/publication/248335931_Assessment_of_pain_induced _by_castration_in_piglets_Behavioral_and_physiological_responses_over_the_subse quent_5_days
- McGlone JJ, Nicholson RI, Hellman JM, Herzog DN. The development of pain in young pigs associated with castration and attempts to prevent castration-induced behavioral changes. J Anim Sci 1993;71:1441-1446 https://pubmed.ncbi.nlm.nih.gov/8325803/
- Davis L. et al. 2019. Practical Alternatives for Managing Castration Pain in Piglets. Prairie Swine Center. Annual Research Report: 8-10. https://www.prairieswine.com/wp-content/uploads/2019/12/Practical-Alternatives- for-Managing-Castration-Pain-in-Piglets.pdf
- National Farm Animal Care Code of practice for the care and handling of pigs. National Farm Animal Care Council, 2014. https://www.nfacc.ca/codes-of- practice/pig-code
- Viscardi AB, Turner 2018. Use of Meloxicam or Ketoprofen, for piglet pain control following surgical castration. Frontier in Vet. Sci.5:299. https://www.frontiersin.org/articles/10.3389/fvets.2018.00299/full
- Dzikamunhenga RS, Anthony R, Coetzee J, et al. Pain management in the neonatal piglet during routine management procedures. Part 1: A systematic review of randomized and non-randomized intervention studies. Animal Health Research Reviews, 2014;15:14-38. https://pubmed.ncbi.nlm.nih.gov/25605277/
- Baysinger, et al. 2021. Proposed multidimensional pain outcome methodology to demonstrate analgesic drug efficacy and facilitate future drug approval for piglet castration. Animal Health Research. Reviews 22,163–176 https://pubmed.ncbi.nlm.nih.gov/34859764/
- DaSilva, MAA, Peretti DC, et 2020. Effect of local anesthesia and/or analgesia on pain response induced by piglets castration. Proc IPVS. 878. https://actavetscand.biomedcentral.com/articles/10.1186/1751-0147-53-34
- de Roest K, Montanari C, Fowler T, Baltussen W. Resource efficiency and economic implications of alternatives to surgical castration without anaesthesia. Animal 2009;3:1522-1531. https://pubmed.ncbi.nlm.nih.gov/22444985/
- Yun J, Ollila A, Valros A, Larenza-Menzies P, Heinonen M, Oliviero C, Peltoniemi O. Behavioural alterations in piglets after surgical castration: Effects of analgesia and Res Vet Sci, 2019; 125: 36-42. https://www.sciencedirect.com/science/article/abs/pii/S0034528818312979
- Keita A, Pagot E, Prunier A, Guidarini C. Pre-emptive meloxicam for postoperative analgesia in piglets undergoing surgical Vet Anaesth Analg 2010;37:367- https://pubmed.ncbi.nlm.nih.gov/20636569/
- O'Connor A, Anthony R, Bergamasco L, et Pain management in the neonatal piglet during routine management procedures. Part 2: Grading the quality of evidence and the strength of recommendations. Animal Health Research Reviews, 2014;15:39-62. https://pubmed.ncbi.nlm.nih.gov/25605278/
- Hansson M, Lundeheim N, Nyman G, Johansson G. Effect of local anaesthesia and/or analgesia on pain responses induced by piglet Acta Vet Sc 2011;53:34- https://pubmed.ncbi.nlm.nih.gov/21627797/
- Pig Code of Practice Scientific Committee. Code of Practice for the Care and Handling of Pigs: Review of Scientific Research on Priority Lacombe (Alberta): National Farm Animal Care Council, 2012. https://www.nfacc.ca/resources/codes-of- practice/pig/Pig_Scientists_Committee_report.pdf
- CVMA Position Statement on Pain Management https://www.canadianveterinarians.net/policy-and-outreach/position- statements/statements/pain-management-in-animals-previously-pain-control-in- animals-position-statement/
- Smith Extralabel use of anesthetic and analgesic compounds in cattle. Vet Clin North Am Food Anim Pract 2013;29:29-45. https://pubmed.ncbi.nlm.nih.gov/23438398/
- CVMA Position Statement on Extra-label Drug Use ELDU in Veterinary Medicine https://www.canadianveterinarians.net/policy-and-outreach/position- statements/statements/extra-label-drug-use-eldu-in-veterinary-medicine/