Piglet pain control during castration still needs answers

Castrating male piglets to prevent boar taint at market age is a common occurrence on US hog farms. However, as consumer interest in on-farm practices and animal welfare grows, producers will need more information on alternative methods, including pain mitigation options during castration.

Ohio State University researchers selected four treatment options to assess the pain mitigation efficacy during and after castration.¹

Piglets within multiple litters were selected at random and assigned to one of four treatments: NSAID only (meloxicam PO), NSAID and lidocaine, lidocaine only and no pain mitigation for a control group.

In all, 111 male piglets were enrolled in the study. The NSAIDs were given orally, and the lidocaine was applied topically immediately after castration, reported Rachel Park, psychology student and advisee of Dr. Monique Pairis-Garcia at Ohio State University, during the American Association of Swine Veterinarians’ 2017 annual meeting.

Piglet behavior was recorded every 5 minutes for the first 5 hours post-castration and tracked periodically for the next 3 days. The behaviors were grouped into four categories:

1. Active (standing, walking)
2. Inactive (sitting, lying)
3. Suckling
4. Pain-related (trembling, huddling, tail wagging, scratching, prostrating)

According to the results, treatment had no effect on the piglets’ activity levels, nor did it impact total pain-related behaviors for the first 2 hours post-castration. This is likely due to the time it takes for the drug to begin effectively working and differences in drug metabolism between piglets.

“Lidocaine will begin to work once it is absorbed through the skin, but oral NSAIDs may not reach significant concentrations for 1 to 2 hours after administration,” Park added.

However, the NSAID treatment did reduce pain 3 and 4 hours after castration as demonstrated by pain behaviors and increased suckling bouts. This is important not only because pain is being managed but also that “administering an NSAID at the time of castration allowed the piglet to more quickly resume natural behavior, which could have a positive result,” she noted.

In the end, Park said, more research is needed — not only to determine when the treatment should be applied and at what dosage, but also whether a multimodal drug protocol would be more effective in managing castration pain in piglets.

¹Park R, et al. Effects of Pain Mitigation During Piglet Castration. Proceedings of the 48^th American Association of Swine Veterinarians’ Annual Meeting. 2017;39-40.