Horse meat substituted for beef in the UK could expose people to a drug called phenylbutazone which can cause a serious blood disorder known as aplastic anaemia. http://www.bbc.co.uk/news/science-environment-21383362  8,000 horses a year are slaughtered for human consumption in the UK. According to the NYT, A trickle of discoveries of horse meat in burgers, first found in Ireland last month, has turned into a steady stream, culminating in the revelation this week that lasagna labeled beef from one big retailer of frozen food, Findus, was in some cases 100 percent horse meat. http://www.nytimes.com/2013/02/09/world/europe/horse-meat-in-food-stirs-furor-in-british-isles.html?ref=world