As the horse meat saga refuses to go away just yet, the most pressing concern for pharmacy has been whether a pain relieving and anti-inflammatory medicine used routinely in horses might have found its way into our burgers and lasagne meals. Phenylbutazone, or “Bute”, was introduced in 1949 for the treatment of painful inflammation such as that caused by conditions such as gout and arthritis. The drug was subsequently banned in humans due to there being a small chance of dangerous side effects.
So why was Bute banned in humans but not in horses? Well, following incidences of serious side effects, such as aplastic anaemia, which causes the bone marrow to stop producing blood cells, as well as suspicions that the drug might be linked with cancer formation, the wisest move was for the Food and Drug Administration was to withdraw the drug from human use. Although these side effects might also happen in horses, Bute is still one of the few tried and tested, effective drugs available in your vet’s medicines chest for equine laminitis, which any horse owner will dread as it is an extremely painful condition similar to gout in horses. The drug is also commonly used for injuries associated with racing. In humans, however, there were plenty of safer alternatives.
Although horses are consumed in some countries such as France, Italy and parts of Asia, they are not routinely farmed in the same way as cattle, sheep and pigs. Therefore, horse meat often comes from the slaughter of working horses that have become injured or retired out of service. To safeguard against the possibility that drugs they have been given during their working life might enter the food chain and cause harm to humans, the process is rigorously controlled by the use of equine “passports”. This system means that when a vet administers a drug to a horse that is potentially harmful in humans, it is recorded in detail in the passport. This will then be checked should the horse be slaughtered, which will prevent the use of its meat in human food. There is always a chance that bad practice will cause this system to fail, which may well have led to the discovery of small amounts of Bute in horsemeat in human food tested by the Food Standards Agency.
As pharmacists, although most of our practice concentrates on the human species, specialist veterinary pharmacists are experts in animal medicines. In fact, they often advise farmers, horse and pet owners on how to use medicines to keep their animals healthy and how to prevent injury or side effects to themselves from handling medicines meant for their animals. For instance, horses will often be administered their pain killers in granule form in their hay, which brings new meaning to the advice given by many pharmacists about taking their tablets with or after food.
In humans, a typical phenylbutazone dose was 100-300mg a day, and reported side effects were sporadic, highly irregular and unpredictable. In contrast, the latest data offered by the Food Standards Agency is that the highest levels found in horsemeat samples tested so far has been just 1.9mg per kg of horsemeat. Even to those that might be “so hungry they could eat a horse”, this would not be enough to produce the 500-600 horse burgers that have been estimated to cause the problems observed in humans taking high doses of the drug. Added to this, the way the body breaks down Bute also lessens that concern, as this drug tends only to be retained in the body for a long time when it has been used at high doses.
For now, I would advise any patient with symptoms that might be linked with the side effects of Bute, such as unexplained bruising, shortness of breath and stomach pains to seek urgent medical advice. However, there are many reasons why someone might experience these symptoms so any pharmacist would give this advice regardless of the horse meat scare.
So to the question on everyone’s mind- could exposure to Bute in horsemeat have had long term effects on the health of the large number of us that may have been partaking in horsemeat suppers without knowing it? In this case, my answer is an educated but confident “neigh”.