Horsemeat scandal: Bute found in eight horse carcasses
BBC News | February 14, 2013

Eight horses, killed in the UK, tested positive for the painkiller bute and six may have entered the food chain in France, the Food Standards Agency said …

… exported to France, where horsemeat is regularly consumed. …

Concerns about horsemeat first came to light on 15 January when tests by Irish authorities found horsemeat in beefburgers made by firms in the Irish Republic and the UK and sold in supermarket chains …

Phenylbutazone (Bute)

Phenylbutazone, often referred to as bute, is a nonsteroidal anti-inflammatory drug (NSAID) for the short-term treatment of pain and fever in animals.

In the United States and United Kingdom, it is no longer approved for human use, as it can cause severe adverse effects such as suppression of white blood cell production and aplastic anemia….

Also:
Dirty little secret: Canada’s slaughter industry under fire
thestar.com | July 30, 211

… A 2010 U.S. study on animals sent to slaughter found the presence of a particularly troubling drug commonly administered to horses — phenylbutazone (PBZ), an anti-inflammatory used for pain relief.

The drug is banned for human consumption by the U.S., Canada, U.K. and European Union because of documented health hazards, sometimes fatal …

Ann Marini, professor of neurology and neuroscience … and a co-author of the study, says every horse in the U.S. receives at least one dose of PBZ each year.

“There’s no horse in (the U.S.) that is eligible for slaughter for human use,” she said in an interview. “It’s a health regulation violation. This is now Canada’s problem. And nothing has been done to end this. We’re sending contaminated horse meat to the people eating it. We’re equally liable.” …