The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
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35 September 2016 THE HORSE TheHorse.com parameters. With proper scientific back- ing, FDA approval, and strict adherence to FDA guidelines, manufacturers can incorporate these medicinal additives (known as drugs) into livestock feed. Therapeutic doses of antibiotics can also be useful in horses, yet, to date, the FDA has not approved their inclusion in horse feed. Here lies the problem: Not all drugs approved for use in other livestock feeds are appropriate or even safe for horses. Some drugs do not pose any equine health risks but might show up in a drug test, resulting in competi- tion suspension and possible financial penalties. With other drugs inadvertent contamination and ingestion can have toxic consequences, resulting in severe health problems and possibly death. Making headlines in the last two years, ionophore contamination of horse feed serves as a prime example of an FDA- approved antibiotic for use in livestock with deadly consequences in horses. Monensin and lasalocid represent two ionophore types added to cattle and chicken feed for disease and parasite prevention and improved feed efficiency. Among livestock, horses exhibit the high- est rate of toxicity to ionophores, making these drugs extremely dangerous when consumed at even the smallest doses. Ionophore intoxication damages heart and skeletal muscle and exerts other effects by mechanisms that are not well- understood, says Cynthia Gaskill, DVM, PhD, veterinary clinical toxicologist at the University of Kentucky's Veterinary Diagnostic Laboratory, in Lexington. "Clinical signs of ionophore poisoning in horses vary depending on the dosage ingested, but can include poor appetite and feed refusal of the grain product, diarrhea, weakness, rapid heart rate, depression, wobbly gait, colic, sweating, recumbency, and sudden death," she says. The first clinical signs typically appear 12 to 72 hours after ingesting a toxic ion- ophore dose and might linger up to about eight days. Animals that recover from sublethal poisoning can develop chronic heart failure, resulting in exercise intoler- ance, poor performance, and death. U.S. Regulations In the United States, the FDA regulates all food intended for human or animal consumption. It works directly with individual states to ensure compliance with all animal feed regulations. Each state can also have its own regulatory programs that complement the FDA's efforts, targeted at making sure feeds do not cause health problems in animals and do not lead to unsafe human food derived from animals. The FDA and states work cooperatively through the Association of American Feed Control Officials ( AAFCO), which has established uniform feed ingredient definitions and proper labeling, to help assure safe feed use. In 2003 the FDA developed the Animal Feed Safety System (AFSS), a program designed to promote production of safe feeds by educating federal and state regulatory employees, conducting inspec- tions, and enforcing regulations. In 2007 and 2008, after major human E. coli outbreaks and cases of melamine toxicity in animals, the U.S. government made changes to improve response efforts and help prevent these events from occurring. The most recent initiative for the AFSS includes the Food Safety Modernization Act of 2010 (FSMA). Signed into law in January 2011, the FSMA focuses on prevention rather than reaction in both animal and human food safety arenas. Under this law, the FDA now: ■ Can require animal feed mills to adopt risk-based preventive controls to ad- dress potential hazards; ■ Can be required to inspect feed mills at a certain frequency; and ■ Has the authority to enforce mandatory recalls. Prior to this act, the FDA did not have the resources to inspect feed facilities on a regular basis and considered recalls voluntary or done at its request. The American Feed Industry Associa- tion (AFIA), the world's largest organiza- tion devoted exclusively to representing the business, legislative, and regulatory interests of the U.S. animal feed industry and its suppliers, also works with the FDA to ensure government regulations are based on sound science and benefit the industry and all it touches, from retail to consumers. "One of the main differences between AFIA and FDA is that FDA creates and en- forces the regulations that impact animal feed," says Miranda McDaniel, AFIA's director of communication. "AFIA can suggest changes to improve these laws, Microbial CONTAMINANTS of Grain SPECIES DISEASE COMMON SOURCE Clostridia spp Botulism Forage that is too wet when baled Escherichia coli Septicemia, cellulitis Feed contaminated by feces of infected animals Salmonella spp Enteritis, diarrhea, septicemia Food contaminated by feces of infected animals Some manufacturers add ionophores to cattle feed. If horse feed is contaminated with this antibi- otic, it can have deadly consequences. ISTOCK.COM