In late December 2014, the South Carolina State Veterinarian's Office and South Carolina Department of Agriculture (SCDA) were contacted regarding three horse deaths in four days on a farm in Beaufort County. The State Veterinarian’s Office is responsible for investigating for possible disease events.
SCDA is responsible for investigating feed contamination originating in SC.
The State Veterinarian's office and SCDA worked cooperatively to assist the farm in determining possible contributors and/or causes. At that same time, SCDA contacted the Food and Drug Administration (FDA) to investigate concerns of potential toxins in the horse feed used by the farm.
On February 2, 2015, the FDA issued the following statements related to the SC investigation:
- The analytical data provided to date by the SC farm for samples analyzed at the Michigan State University toxicology laboratory indicates monensin is present at or below the levels of detection for the analysis.
- The highest detectable level reported in the samples submitted by the SC farm to the Michigan State University lab was 1.0 part per million (ppm).
- The only necropsy that was performed on a horse suspected of monensin toxicity did not disclose any cardiac/heart damage. Although there is no established tolerance for monensin in horse feed, the FDA is not aware of any published literature that a level of 1.0 ppm of monensin in horse feed has posed a health risk to these animals.
- The FDA has seen evidence that levels in the range of 210-300 ppm monensin in horse feed have been very toxic and resulted in fatalities. In such cases there have been Good Manufacturing Practices (GMP) non-compliances that corresponded with the observed levels.
- The inspection of the feed manufacturing facility responsible for producing the suspect feed did not reveal any non-compliances with GMPs.