Study Evaluates Banned, Controlled Substances in Horse Feed
The Fédération Equestre Internationale’s (FEI) Clean Sport initiative is designed to do just what the name suggests: promote equestrian events in which horses and humans are free of banned or controlled substances. “The use of substances with the potential to affect equine performance, health, or welfare and/or with a high potential for misuse are contrary to the integrity of equestrian sport and the welfare of horses,” it states.

As part of its efforts to keep sports clean, the FEI uses regular anti-doping testing that can detect small quantities of prohibited and controlled substances, whether administered intentionally or not. Swiss researchers recently determined that at least some of those substances could be getting into horses’ bodies unintentionally via small quantities in commercial feeds, supplements, and other products.

Morphine, codeine, noscapine, papaverine, colchicine, and atropine all appeared in minute quantities in more than half of the 28 feed samples tested in the researchers’ recent study. However, this is not cause for alarm, they stressed. It’s just cause for awareness.

“We found doping-relevant substances in very small concentrations with a sensitive laboratory method (electrospray-ionisation high-pressure-liquid-chromatography mass spectrometry, or ESI-LC-MS/MS) in the feed samples,” said Conny Herholz, PD, DrMedVet, FTA, Dipl. ECEIM, ATA, of the Bern University of Applied Sciences, School of Agricultural, Forest, and Food Sciences, in Zollikofen.

“The results show that feed can contain doping-relevant substances,” she continued. “But we don’t yet know if these concentrations are sufficiently high to be detected in the blood or urine of the horse.”

In their study, Herholz and colleagues tested 28 samples of commercial horse feed, packaged primarily in Switzerland and Germany, for the presence of nine naturally occurring doping substances. This included four substances on the FEI banned list (noscapine, papaverine, colchicine, and thebaine) and five substances on the FEI controlled medications list (morphine, codeine, atropine, theobromine, and theophylline).

They found that 18 (64%) of the feeds in their study showed evidence of contamination by one or more of these substances, Herholz said. Wheat bran samples were positive for noscapine, theobromine, atropine, and colchicine. Red soybean samples contained noscapine, theobromine, and atropine. Noscapine appeared in barley. And even the hay had positive results for three substances: noscapine, papaverine, and atropine.

Meanwhile, two methods of analysis of poppy seeds from Swiss farms revealed the presence of morphine, colchicine, codeine, noscapine, and papaverine. As poppy seeds could accidentally contaminate feed or hay at any stage of production, they could possibly account for the appearance of substances in drug testing, Herholz said. This might be an explanation for the recent doping cases involving two Swiss riders whose horses tested positive for poppy-related substances.

“Doping-relevant substances like in poppy seeds can contaminate feed at any stage of the value chain—beginning from the seed, to cultivation, harvesting, feed mills and transport up to the end consumer,” said Herholz. “For the horse owner, it’s important to pay attention, for example, to the hygienic storage of feed material in the stable.”

That means keeping feed stored in well-sealed containers to prevent accidental contamination by people, animals, or even wind and air, that could unknowingly transport poppy seeds into a horse’s food supply, she said. It also means being careful of the kinds of treats you give your horse.

“Poppy seed can contain different concentrations of opioids, as we see in our study,” she said. “If a horse eats bread with poppy seeds, which contain high concentrations of opioids, it can be enough to provoke a positive doping test result (although this concentration would not result in a visible reaction of the body).”

From a health perspective, there’s little to fear about the accidental presence of poppy seeds in food, however. “Considering the amount of morphine we detected in one oat sample, in order for the horse to have a visible bodily reaction, he would need to consume 2,083 kilograms (more than 4,500 pounds) of those oat grains,” Herholz said.

Whether the small amounts present in commercial products is enough to trigger a positive doping test remains to be determined. “Very little data exists at the moment about what concentrations of doping-relevant substances (consumed) would lead to a positive test result in urine or blood,” she said. “Further research is required.”

In the meantime, owners don’t need to avoid commercial feeds out of fear of doping substance contamination, she said. And the FEI doesn’t need to redesign its doping test strategy. In general, there’s no reason to panic.

However, owners can practice good feed management, such as buying food specifically designed for horses (not other animals), checking for holes in packaging at purchase, storing feed in tightly closed containers, and keeping horse food away from other animals’ food and pharmaceutical products. Competitors should also keep package labels and a small sample of food for testing purposes in the event of a positive test, Herholz said.

The research received the support of the Swiss feed industry, “which is aware of the problem,” said Herholz. Charles F. Trolliet, DVM, president of the Swiss Equestrian Federation (SVPS/FSSE), in Bern, participated in the study.

The study, “Doping-relevant substances in feed for horses,” was published in Switzerland Arch Tierheilkd.