10/12/2021
Cute as a bug…NOT!
Many people believe that alfalfa is the best hay to feed in winter for warmth, due to the metabolic heat that your horse generates to metabolize the extra protein this grass contains. If you, too, are planning to feed alfalfa this winter, please be aware that your horse could be at risk for potentially deadly blister beetle toxicity — even if you are using alfalfa that has been harvested months or years previously.
"The blister beetle (Epicauta) is highly toxic to sheep and cattle, but primarily to horses," says Dr. Benjamin Espy. "As little as four (4) to six (6) grams of blister beetles can be deadly to a 1100-pound horse. Blister beetles swarm in alfalfa fields and are drawn into bales by accident. Even small parts of these beetles are toxic to a horse, and whole insects need not be present to be dangerous."
There are many representatives of the species Epicauta, so we encourage you to contact a county agricultural agent to familiarize yourself with the poisonous beetles in our area or the geographical region where the hay you purchase is harvested. Be sure to check alfalfa for the presence of blister beetle prior to feeding, especially if you feed alfalfa hay from a new or unknown harvesting source.
If you suspect your horse is showing signs of toxicity, call your veterinarian immediately. While there is no antidote for the toxin found in blister beetles, your veterinarian may still be able to save your horse by providing supportive care to combat dehydration, help evacuate toxins from the gastrointestinal tract and delay potential absorption.
You can read Dr. Espy's article on blister beetle poisoning in full on our website at https://aaep.org/horsehealth/blister-beetle-poisoning