Commercially reared piglets receive a number of routine management procedures including castration, tail docking, teeth clipping, and vaccination. Castration of pigs is done primarily to avoid boar taint, an objectionable flavor found in the meat of mature males. However, due to the pain caused by this procedure and the fact that analgesics are not commonly used, surgical castration of piglets is a welfare concern. The pork industry is responding to this concern by seeking effective ways of providing pain relief at castration, or alternative methods for reducing boar taint. This study investigated a novel approach for providing analgesia to piglets, in which the analgesic drug, Metacam®, was administered to sows, and obtained indirectly by piglets through the sow’s milk. Our main objectives were to determine how much of the drug was transferred to piglets, the time course of drug absorption and elimination, and whether or not this treatment would reduce pain responses after castration. Administration of the drug to the piglets through the sow’s milk could eliminate the need to handle the piglets twice at castration and decrease the labor requirements of injecting each piglet. When sows were injected with 0.5, 0.75 or 1.0 mg/kg Metacam®, drug levels in milk were found to increase over time, peaking at approximately 215 ng/ml at 3 h following injection. Unfortunately only a small amount of drug was transferred to piglets via the milk, with maximum levels of less than 3 ng/ml observed over a 5 h period. This drug concentration is only a fraction (less than 1/100th) of the amount achieved typically by administration through intramuscular injection, and is not believed to be sufficient to provide effective pain relief. However, use of an alternative drug or higher drug dosages and longer wait times may provide a better result. Increasing the dose of drug administered to the sow would increase the amount of drug available to the piglets in the sow’s milk, but this approach is limited due to potential effects on sow health and cost of the drug. Overall, this study showed limited success in transferring the analgesic, Metacam®, through the sow’s milk to piglets: the drug was successfully transferred to piglets, but the rate of transfer was slow and the quantity transferred was low. Other analgesic drugs such as Ketoprofen® could be tried using a similar approach, as this method has the potential to significantly reduce labor requirements for handling and injecting piglets, as well as reducing stress in piglets by minimizing handling.

Researcher contact information: Dr. Jennifer Brown, Prairie Swine Centre, PO Box 21057, 2105 8th Street E., Saskatoon, SK, Canada, S7H 5N9, Tel: 306 667-7442, Email: