Notification to Equine Owners about Fumonisin-Contaminated Feed

DOVER, DE (May 30, 2025) – The Office of the State Veterinarian is notifying the public of cases of neurologic disease in horses in the Kent County area. Many of the cases have been associated with feeding a corn-based feed. Anyone using feed purchased in April is encouraged to contact their supplier to see if they are aware of any related concerns.

Symptoms from equine cases were recorded by area veterinarians between April 22 and May 17. The Office of the State Veterinarian and a local equine veterinarian submitted three samples of feed fed to affected horses for toxin analysis. All samples returned with levels of a fungal toxin called fumonisin. The levels in the samples significantly exceeded five parts per million (ppm), the maximum level recommended by FDA.

Fumonisin is a toxin produced by mold (mycotoxin) that grows on corn. The amount of contamination can vary due to weather during harvest and harvest periods, improper storage and other factors. Dry periods followed by rainfall just before and during harvest can create optimal conditions for mold growth. Insect damage and high-moisture content (18-23%) in storage can increase levels of toxins. Proper storage and management of corn and other feed grains are vital preventative steps.

Fumonisin can harm various livestock animals depending on the levels of contamination and the amount ingested, with horses and rabbits being most sensitive. The toxin causes softening of the brain and subsequent neurologic signs including lethargy, head pressing, wobbly gait, tremoring, and circling, and progression to recumbency and death. The samples submitted by the Office State Veterinarian and the local equine veterinarian had levels ranging from 31 – 101 ppm where as safe, quality feed should not have Fumonisin levels exceeding one ppm.

Those caring for sensitive animals are reminded of these best practices when purchasing feed:

• Make sure that the manufacturer has a guarantee that the feed has been tested for mycotoxins before distribution. This is commonly found on the manufacturers’ website.
  Consult with your veterinarian about the best brand and type of feed for your animal based on their age, lifestyle, and breed.
• Use feed that is produced specifically for the animal species you own. There may be additives or nutrient levels in feed produced for other species that are toxic for horses, even at residual levels.
• It is critical for livestock owners to have a relationship with a livestock veterinarian. This veterinary-client-patient relationship is best established when animals are healthy so that the veterinarian is familiar with the animal and their baseline health status. If owners notice their animals experiencing signs of illness, they should contact their veterinarian immediately.

Animal owners who believe they may have purchased contaminated feed are instructed to dispose of the feed immediately and not to feed the product to their livestock or poultry. Owners with questions or concerns about feed should contact the supplier for more information. Further guidance on feeding should be sought from a veterinarian.

Animal health questions should be directed to the Poultry and Animal Health Section of the Delaware Department of Agriculture at 302-698-4500.

Resources:

https://extension.psu.edu/from-aflatoxin-to-zearalenone-key-mycotoxins-you-should-know-fumonisins

https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-fumonisin-levels-human-foods-and-animal-feeds