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Translactational analgesia technology for the improvement of swine welfare during castration and tail docking
Oral meloxicam was administered to sows post-farrowing to investigate a novel route of providing analgesia to processed piglets via translactational transfer. Physiologic indicators of piglet pain were analyzed to determine the effects on pain control.
Ten sows were selected, based on farrowing date, to receive either meloxicam (30 mg/kg) or equivalent volume of whey protein placebo in their daily feedings starting four days post-farrowing and continuing for three consecutive days. Blood and milk samples were taken from the sows at 12 hour intervals beginning directly prior to feeding through the end of the study. On Day 5 post farrowing, three boars and three gilts from each litter were castrated or sham castrated, tail docked and given an iron injection. Piglet blood samples were collected immediately before processing, and then at predetermined times over an 84 hour period until the end of the study. Additionally, infrared thermography (IRT) images were captured at each piglet blood collection point. Eight days post- farrowing, tissue samples were collected at necropsy from sows and piglets.
Piglet plasma from each litter was tested to confirm the presence of meloxicam using a validated HPLC- MS technique. Meloxicam was found in all of the litters in the treatment group (Mean ± SEM:285 ± 61 ng/mL). Levels reached concentrations known to be effective in equine (EC50) in 4 of the 5 treatment litters (Figure 1).This value was extrapolated because the level in swine in currently unknown.
No adverse clinical effects were noted in meloxicam treated sows and piglets. On histopathology, subacute gastritis was noted in 2/5 meloxicam treated sows. Similar lesions and gross button ulcers were seen in 10/11 of those same sows’ piglets.
IRT demonstrated significant differences in cranial temperature between treatment and control piglets (p<0.0001). There was a time by treatment interaction for percent change in piglet serum cortisol (p<0.0001). Meloxicam treated piglets had lower cortisol change at one hour post-castration those treated with whey. (p<0.0001). Measurement of Substance P indicated no difference between control and meloxicam treated groups (p=0.8685).
This study demonstrates the successful transfer of meloxicam in sow’s milk and description of physiologic pain indicators. It provides the foundation for future research into refining a novel, efficacious, and practically administered analgesia method.
Keywords: castration, lactation, welfare