Use of Meloxicam or Ketoprofen for Piglet Pain Control Following Surgical Castration

Abstract

Surgical castration of piglets is performed routinely on commercial pig farms, to prevent boar taint and minimize aggression. While this procedure is known to be painful, piglets are generally not provided any analgesic for pain relief, leading to welfare concerns. The objectives of this study were to assess the efficacy of two non-steroidal anti-inflammatory drugs (NSAIDs), meloxicam (MEL) (0.4 mg/kg or 1.0 mg/kg) and ketoprofen (KET) (6.0 mg/kg) in reducing behavioral indicators of pain in castrated piglets. This study also examined the utility of the Piglet Grimace Scale (PGS) as a pain assessment tool. Nineteen litters of 5-days-old male piglets (n = 120) were used and piglets within a litter were randomly assigned to one of eight possible treatments: 0.4 mg/kg MEL-castrated or uncastrated, 1.0 mg/kg MEL-castrated or uncastrated, 6.0 mg/kg KET-castrated or uncastrated, saline (castrated control), or sham (uncastrated control). Treatments were administered intramuscularly (IM) 20 min prior to surgical castration. Piglets were video recorded for 1 h pre-procedure, for 8 h immediately post-castration and for another hour, 24 h post-procedure. Twenty-one behaviors and postures were scored continuously for the first 15 min of each hour and 1,156 still images of piglet faces were collected and scored using the PGS. Within each treatment group post-castration, castrated piglets displayed significantly more pain-related behaviors than uncastrated piglets (0.4 mg/kg MEL: p = 0.0339, 1.0 mg/kg MEL: p = 0.0079, 6.0 mg/kg KET: p = 0.0034, Controls: p < 0.0001). Castrated piglets also grimaced significantly more post-procedure than uncastrated piglets (p = 0.0061). Compared to the castrated control, none of the NSAID treatments significantly reduced piglet pain behaviors (0.4 mg/kg MEL: p = 1.0000, 1.0 mg/kg MEL: p = 0.9995, 6.0 mg/kg KET: p = 0.4163) or facial grimacing. Piglets demonstrated significantly more pain behaviors 24 h post-castration than at all other time points (p < 0.0001). The PGS was a less effective measure to detect acute pain; however, our findings suggest it does have utility as a pain assessment tool in neonatal pigs. Our findings also indicate that the use of these NSAIDs were ineffective at alleviating castration-associated pain in piglets.

Is the Piglet Grimace Scale (PGS) a Useful Welfare Indicator to Assess Pain after Cryptorchidectomy in Growing Pigs?

“…According to the legislation in force in the European Union (Council Directive 2008/120/EC of 18 December 2008), pigs after their seventh day of life should be castrated under general anesthesia and should receive additional prolonged analgesia, e.g., ketoprofen. Viscardi and Turner demonstrated that ketoprofen was ineffective in alleviating pain resulting from surgical castration in 5-days piglets [17]. In our study, the anesthesia protocol included ketamine and pre-incisional and intratesticular and lidocaine.…”

Comparative Plasma and Interstitial Fluid Pharmacokinetics of Meloxicam, Flunixin, and Ketoprofen in Neonatal Piglets

“…Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly studied treatments for processing-associated pain (11,12), however, there are conflicting data supporting their use at castration or tail-docking. Particularly, there is conflicting data supporting the use of meloxicam at the European label dose of 0.4 mg/kg (13)(14)(15)(16). There are no pharmacokinetic studies of meloxicam in piglets <1 week-of-age, which is surprising given the larger number of studies assessing the efficacy of meloxicam for pain-alleviation following castration, compared to other NSAIDs.…”

Grimace Scores: Tools to Support the Identification of Pain in Mammals Used in Research

“…The use of these grimace scales can be a vital tool to enable mitigation of the experience of pain in animals and refine animal welfare outcomes [ 41 , 60 , 66 , 75 , 76 , 82 , 100 , 114 , 128 ]. Unlike other types of pain assessment, grimace scales are spontaneous and usable in real-time [ 7 , 45 , 55 , 76 , 87 , 91 , 92 , 101 ]. They can also be matched and corroborated against other known indicators of pain or painful diseases including, but not limited to, lameness [ 37 , 64 , 82 , 85 ], cortisol [ 70 ], behavioural ethograms [ 81 , 85 , 91 , 92 ], acute laminitis [ 37 ], mastitis and foot rot [ 82 ].…”

“…Unlike other types of pain assessment, grimace scales are spontaneous and usable in real-time [ 7 , 45 , 55 , 76 , 87 , 91 , 92 , 101 ]. They can also be matched and corroborated against other known indicators of pain or painful diseases including, but not limited to, lameness [ 37 , 64 , 82 , 85 ], cortisol [ 70 ], behavioural ethograms [ 81 , 85 , 91 , 92 ], acute laminitis [ 37 ], mastitis and foot rot [ 82 ]. A future area for development and benefit is the use of software automation in the development and scoring of facial expressions.…”

“…At present, there is not a single non-invasive, low-cost behavioural, physical or physiological pain assessment technique that is spontaneous, pain-specific, easy to train and quick to use ( Table 1 ) [ 5 , 15 , 16 , 21 , 38 , 46 , 53 , 78 , 86 , 87 , 88 , 89 ]. With the exception of some behavioural ethograms [ 63 , 78 , 90 , 91 ], other methods are unable to give a reliable dose-dependent response to pain. While many pain identification methods have their use and benefits, their use in the cage or pen-side management of animal pain and/or in the timely and appropriate application of humane intervention is limited.…”