What is the physiologic response to pain in castrated piglets?
By Stephanie Anderson, Magdiel Lopez-Soriano, Kristen Messenger and Monique D. Pairis- Garcia
Castration occurs soon after farrowing on commercial swine farms. Castration is routinely performed to control unwanted breeding, limit aggressive behaviors, fighting and prevent boar taint, a foul odor produced by intact males that affects pork quality.
Painful procedures like castration are routinely performed in pre-weaned piglets without any pain control or relief. Currently there are no Food and Drug Administration (FDA) approved drugs to control pain in pigs. Without the use of pain relief, castrated piglets will experience pain and be shown by changes in behavior and performance. Pain specific responses to castration can include reluctance to move, back arching, and increases in stress response as shown through increased cortisol levels.
The objective of this study was to assess the efficacy of flunixin meglumine for castration in piglets using physiological response to pain. Flunixin meglumine, a non-steroidal anti-inflammatory drug (NSAID) often used extralabelly for lameness in sows, was given intranasal at 2.2 mg/kg 20 minutes prior to castration to 24 piglets between the ages of 6-9 days old. An additional 24 piglets were enrolled in the study, castrated in the same manner as the flunixin piglets, but not given any pain relief (Control piglets). Flunixin was chosen due to previous studies in our lab showing its efficacy in controlling castration pain.
Physiological pain response was assessed by evaluating blood cortisol levels collected 24 h prior to castration, immediately after castration, and 3 h after castration. Immediately following castration, piglets given flunixin intranasal had lower cortisol concentration compared to piglets castrated without any drug (Figure 1.). Cortisol levels returned to baseline 3h post-castration and there were no differences in cortisol levels between flunixin treated and control piglets.
These results support the use of IN Flunixin to mitigate pain post-castration as shown by decreased cortisol levels. Future projects will focus on refining this technique and applying it on a larger scale.
Anderson is a third-year student, Lopez-Soriano is a researcher assistant, Messenger and Pairis-Garcia are associate professors, all in the College of Veterinary Medicine at North Carolina State University.
