Horses are given phenylbutazone as a treatment for arthritis and other inflammatory diseases. This drug can accumulate in the system and cause ulceration, kidney damage, and internal bleeding in the horse, or in anyone who eats the meat. 'Clandestine' horse meat or products in wrongly labelled food is hardly likely to have been tested for 'bute'. In Britain over the last hundred years, horses slaughtered for meat were generally the old and/or sick ones. They were probably riddled with worms, diseases of various kinds and not a good option to put on a plate. IF (?) horsemeat is honestly sourced from inspected and disease-free stock, humanely treated in life and slaughtered under correct prodedures, I see no reason why people shouldn't eat it. I wouldn't, but there you are. But I do strongly object to dishonest practices in food production and illegal representation on a label of what is, in fact, in the stuff you are going to ingest.