Several years ago, Canadian hog producers won market share in the lucrative Chinese pork market by ditching ractopamine, a drug that is added to feed to speed weight gain.

The Canadian industry all but eliminated use of the growth promoter that is banned in China, giving it an edge over the U.S., where nearly half of hog operations still used ractopamine.

That’s why it came as a shock to Canada when earlier this month, a pork shipment from a Quebec-based processor tested positive for ractopamine. That detection spurred heightened scrutiny and now China has suspended all imports of meat from Canada because of forged health certificates.

While Canadian officials were looking into where the drug-laced meat came from, there may be more pork that ends up in the U.S. or in other Asian countries that do not ban ractopamine.

The U.S. Food and Drug Administration approved its use in 1999 while China has banned it since 2002, arguing the drug can harm people who consume meat raised with it.

Use of the additive, which can allow livestock producers to use less feed, increased after a severe drought in 2012 that cut crop production and pushed corn and soybean prices to record highs.

--With assistance from Ashley Robinson