Country of Origin Labelling (COOL) regulation has been applied in the United States meat sector since October 2008. The industry must label beef, lamb and pork (ground meat and muscle cuts) sold through retail outlets according to its country of origin. The labelling requirements create differentiation at the retail level and may impose additional costs on producers, processors and retailers in the U.S. and elsewhere. The purpose of this analysis is to investigate whether there has been structural change in U.S. import demand for Canadian hog/pork products. Given that COOL has been in place for a limited period of time, we implement statistical procedures that are robust to structural change occurring at the end of the sample. We find evidence that COOL has impacted U.S./Canada slaughter hog trade flows. While Canadian feeder hog prices appear to have declined concurrently with the introduction of COOL, statistical hypothesis testing found little evidence of structural change for feeder hog trade flows that could be associated with COOL.