This article is the single best argument against American horse meat entering the food chain. Scientific, thorough and well-written, I encourage you to read it. Below is a short excerpt of the article as well as a link to the rest of the article.
It is not a secret that horses in America are not considered food animals but are rather regarded as large companions or athletes, bred to trust their human masters, provide them leisure and to perform at the track like professional sportsmen, and as such, horses are raised, fed and medicated in a totally different fashion than real food animals like beef cattle, sheep or pigs. Never considered part of the food chain in this country (not even in the hardest times, where it was sold primarily to poor European immigrants as a cheap replacement for beef), horses are routinely administered all kinds of drugs, food supplements and miscellaneous substances that, under current American and European laws, theoretically prohibits them from being used as human food yet, last year alone, more than seventy million pounds of tainted horsemeat from America’s pet horses were sent abroad for human consumption.
It has been speculated since the early 90’s that extensive mustang trafficking has occured. The BLM’s closed book policy served to enhance this. Horses to Slaughter, Anatomy of a Cover-up within the Wild Horse and Burro Program within the Bureau of Land Management was published in 1997.
While groups have been fighting the BLM for decades, it took just under 15 years for the feds to catch the first slaughter truck. An excellent article was published in horseback magazine. Whether you are a horse person or not, I encourage you to read it in its entirety. This is an example of a lot of untracked federal money and property dissapearing. Are there other sieves out there?
A comprehensive look at American Horse Slaughter.