Blister Beetle Poisoning in Florida

At press time, three horses had died of blister beetle poisoning in Clay County, Fla., and two others returned home following treatment at the University of Florida after eating alfalfa hay contaminated with blister beetles. The hay was delivered from a supplier in Oklahoma.

Marginned blister beetle
Marginned blister beetle

Courtesy Dr. Ric Bessin

Blister beetles, any of six species of the genus Epicauta, can inhabit alfalfa and clover fields from the central through the southern United States. They cause inflammation and blistering of the skin within hours of contact. If ingested, cantharidin, a toxic substance in the beetle, is absorbed and rapidly excreted in the urine, causing inflammation of the digestive and urinary tracts. Horses can suffer severe poisoning from even a few beetles, alive or dead (hay processing can kill the beetles and release the toxin). Decreased feed intake, frequent drinking and urination, colic, and depression are signs of blister beetle poisoning. Blister beetle poisoning can cause severe pain, shock, and death in horses within a few hours.

Bill Jeter, DVM, diagnostic veterinary manager for Florida's Division of Animal Industry, said the contaminated hay was sent from Oklahoma to a Florida feed distributor. He said, "I would assume that the distributor tracked down the hay within 24-48 hours and removed it--we have had no other reports of horses with (toxicity) or other hay being contaminated."

He said the affected horses all lived in the same barn. "The owner had six horses--one didn't eat his hay that night and the other five got sick. Three of the (five affected) horses are dead, and one of the other two had severe laminitis and coffin bone rotation," added Jeter. Both horses have returned home.

Jeter explained that the toxin causes severe endotoxemia and kidney damage, leading to laminitis.

Florida Agriculture Commissioner Charles H. Bronson issued an alert on July 25 advising horse owners to carefully check their hay supplies and feedstuffs to ensure quality and to safeguard their horses. Any horse owners with questions or concerns about their hay supplies were advised to contact their feed dealers or veterinarians.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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