Concerns about a veterinary drug
While horse meat is not itself a food safety hazard, food inspectors are concerned it may contain the veterinary drug phenylbutazone, or "bute," commonly used to treat horses.
Meat from animals treated with phenylbutazone may pose a risk to human health and is not allowed to enter the food chain as it may pose a risk to human health.
Findus has been ordered to test the lasagna withdrawn from shelves in the United Kingdom for the drug's presence.
The revelations have revolted many meat eaters in the United Kingdom, where horse meat is generally considered taboo, although it is commonly eaten in neighboring France, as well as countries including China, Russia, Kazakhstan and Italy.
The discovery of pig DNA in beef products is of particular concern to Jews and Muslims, whose dietary laws forbid the consumption of pork products. Jewish dietary laws also ban the eating of horse meat.
The UK Justice Ministry confirmed last week that a number of meat pies and similar items supplied to prisons in England and Wales were labeled and served as halal -- prepared in compliance with Islamic dietary law -- but contained traces of pork DNA, the Food Standards Agency said.
Horse meat is not commonly eaten in the United States, but the country does export it to Canada and Mexico. Congress passed a bill in November 2011 that lifted a 5-year-old ban on the slaughter of horses for meat in the United States.