Surgical castration of piglets continues to be a routine procedure in Canada. Production of intact males has been a
nonstarter in Canada. The use of immunization against boar taint has gained some traction. The results of previous studies that assessed the effectiveness of non-steroidal anti-inflammatory drugs (NSAIDs) for pain relief in
castrated males have not been consistent. The use of NSAIDs does not address the pain that is generated from skin incision or removal of the testicle. Local or general anaesthetics are required for that role in pain relief.
These Canadian researchers wanted to revisit the efficacy of two 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. The 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.
The authors attempted to use a very robust schedule of observations and were using a wide array of behavioural pain assessments. Piglets were video recorded for 1 hour pre-procedure, for 8 hours immediately post-castration and for another hour, 24 hours 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 hours post-castration than at all other time points (p < 0.0001). The authors concluded that the PGS was less effective in detecting acute pain but their findings suggest the PGS does have utility
as a pain assessment tool in neonatal pigs.
Take Home Message
The use of NSAIDS analgesics for pain control at castration at best reduces pain but certainly does not eliminate pain at or after castration.
Expect to see a continued pressure for the provision of effective anaesthetics and analgesics
for pigs that are castrated.
Expect also to see the call for an outright ban of castration as an end point for animal rights
Submitted by Christine Pelland, DVM
Ref: Viscardi AV, Turner PV. Use of Meloxicam or Ketoprofen for Piglet Pain Control Following Surgical Castration. Front Vet Sci. 2018 Nov 26;5:299. doi: 10.3389/fvets.2018.00299. eCollection 2018.