Cases of equine feed contamination have made national headlines in the last few months, many of them with deadly consequences. Beginning in Florida, where 22 horses were poisoned by monensin-contaminated feed from Lakeland Animal Nutrition, and most recently in South Carolina, where three horses were supposedly poisoned by ADM Alliance Nutrition, feed and concerns for its safety have spread across the United States like wildfire.
The most recent cases of confirmed and suspected equine feed contamination have centered around the ionophore monensin.
“Ionophores are types of antibiotics used in beef, dairy, sheep, goat and poultry feeds to prevent coccidiosis, a parasitic disease, and to improve feed efficiency,” said Amy Parker, manager of technical services and equine nutritionist for McCauley Bros,. Inc., based in Versailles, Ky.
Parker said ionophores also increase weight gain and efficiency, and prevent bloat and acidosis.
“These products are not intended for equine use,” she said. “Horses are extremely sensitive to ionophore toxicity, and consumption can result in serious health problems and often death.”
Other feed additives designed for non-equines have caused equine feed contamination, said Kristen Janicki, MS (Equine Nutrition), PAS. Some of these additives have resulted in positive drug tests when ingested by racehorses.
Parker also points out that horse feeds (or any livestock feed) can be contaminated by other substances that are not additives, including mold, mycotoxins, Salmonella, and E. coli.
What Causes Contamination
“Feed contamination can come from a variety of sources,” said Janicki. “It can come from everything from pre-harvest of the individual ingredients [grains], feed manufacturing, storage and transportation, to the storage of feed on the farm.”
Although lab results have linked the positive drug tests in those cases to contamination of the feed, there has not been a finalized report as to how or why the feed was contaminated.
However, the most likely cause of the recent equine fatalities from monensin poisoning is from the production of equine feed and medicated feeds in the same facility.
Parker said mills that produce medicated feeds must be FDA approved.
“FDA approved medicated mills must follow FDA clean-out procedures to eliminate contamination,” said Parker. Contamination in a mill can occur one of two ways: either the mill is not cleaned out according to FDA protocol, or there is an equipment failure that allows for contamination.
FDA clean-out procedures state that “the firm must have written procedures to prevent unsafe carry-over of drugs into subsequent production of animal feeds. These procedures may include flushing, physical clean-out, sequencing or any other procedure which has been shown to prevent carry-over of unsafe drug residuals into animal feeds.”
According to the FDA, flushing “is the process of using an ingredient, usually an abrasive-type material such as corn, soybean meal, peanut hulls, etc., after the production of a batch of feed, through the manufacturing equipment and associated handling equipment (e.g. conveyors) for the purpose of cleaning out any drug residue.”
Physical clean-out of equipment may include vacuuming or sweeping. Sequencing refers to the order in which different types of feeds are produced in the mill. Horse feed should not be mixed immediately after a feed containing monensin.
Proper clean-out of vehicles carrying feed is also a necessity as cross-contamination can occur, according to Parker. A truck that carries medicated feed or an ingredient for a medicated feed to a mill, then carries non-medicated feed or another ingredient directly after could contaminate the non-medicated load with ionophores, said Parker.
“Ultimately, any time you are producing medicated feeds in the same facility as non-medicated feeds, there is a risk of contamination,” said Janicki. “The goal is to reduce that risk as greatly as possible, though the only way to completely eliminate the risk is by separating the production of medicated and non-medicated products at facilities intended for each one.”
What Monensin Poisoning Looks Like
Unfortunately, contaminated feed is not discernible, either visually or through touch or smell. Additionally, very small doses of monensin can be fatal to horses if ingested: only 0.5 to 1.5 grams for a 1,000-pound horse, according to the Reata Equine Veterinary Group based in Tuscon, Ariz.
Monensin is absorbed in the gut and reduces muscles' ability to contract, particularly those in the heart and diaphragm. A horse with monensin poisoning may go off his feed and act depressed or tired; he may exhibit muscle weakness and incoordination; and he may develop a cardiac arrhythmia.
Treatment of a horse with monensin poisoning can include the removal of feed in the stomach by gastric lavage, support with IV fluids, and the administration of anti-arrhythmic drugs.
The prognosis for a horse that has ingested contaminated feed is dose-related and depends on the amount of damage to the heart muscle. It is also dependent on how quickly the horse receives treatment for the poisoning.
What Spurs A Recall?
If it's suspected that a horse has ingested contaminated feed, a veterinarian should be called immediately. Once the horse's issues have been addressed, the feed manufacturer and state regulatory services should also be contacted.
Unsafe animal feed is reported through the FDA and state officials' surveillance programs, though the public also plays an important role in reporting, noted Janicki. Any consumer concerned about the safety of a product can file a report here.
After the report is submitted, depending on the seriousness of the issue, it will either be investigated immediately or designated from another action, such as reviewing the information at the next inspection of the manufacturing facility, explained Janicki. An officer may visit the manufacturing facility and the consumer, and may take samples of unopened feed for testing.
Manufacturers can recall their products at any time to ensure the safety of consumers. The FDA may request that the manufacturer voluntarily recall a product after the evaluation of the health hazards that exist with the complaint. The FDA may also formally request or mandate a recall, as well.
“Care must be given when interpreting 'positive' laboratory results,” Parker warned. ”Laboratory tests are only accurate for the range of sensitivity for a given substance. A laboratory result that reports a concentration of the suspected substance does not necessarily confirm a contamination.”
Informed Decision Making
As a horse owner or one who cares for horses, it's imperative to be informed not only of where the horses' feed is coming from, but also of what else is being produced in the mill that manufactures it. While there are regulatory steps in place from the FDA to help prevent contamination of feed with monensin and other ionophores, due diligence is required both on the part of the mill and its workers, and by others involved in the transport of ingredients used in feed and the finished product.
To be fully informed, Parker suggests some questions to ask of the feed mill. They include:
-Is the feed mill multi-species?
-Does the feed mill produce medicated feeds?
– Is it an FDA-approved medicated mill?
-Are all of their products made in one location?
-What steps does the manufacturer take to prevent contamination?
-Is the mill following the FDA clean-out procedures?
-What are the manufacturer's policies regarding incoming ingredients?
-Have they ever had a feed recall for any reason? (She notes that recalls can also occur for non-contamination issues.)
Despite all the bad news regarding horse feed in the news today, the outlook is positive.
“The FDA and state officials rely heavily on voluntary compliance of feed manufacturers simply because there isn't enough manpower to adequately assess every manufacturer in each state,” Janicki said. “This has led to a more reactionary approach to animal feed safety rather than preventing contamination in the first place.”
But changes are coming. The FDA Food Safety Modernization Act (FSMA), the most sweeping reform of food safety laws in more than 70 years, was signed into law by President Obama on Jan. 4, 2011.
“It aims to ensure the U.S. food supply (including livestock feed) is safe by shifting the focus from responding to contamination to preventing it. The budget for 2015 includes major funding for this program, mostly for the manpower it will take to run such a program effectively, Janicki said.
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