What you see. The starting point for addressing any equine health related issue is your observation.


Blister Beetle in Hay, Horse May have Eaten Some


This is a rare observation. Usually beetle carcasses are only found when the hay is carefully examined, following signs of illness in a horse. They are tiny and very easily overlooked when examining hay. Blister beetle carcasses are found almost exclusively in alfalfa. A small number of these carcasses contain enough of the toxin cantharidin to kill a horse.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours

your role


What To Do

If you discover blister beetles or similar insects in your hay, immediately stop feeding the hay to your horses. Have your vet examine the beetles to definitively identify them. Contact your hay supplier and warn them about your findings.

What Not To Do

Do not assume that it is ok to feed the hay if you only find a few blister beetle carcasses.

your vet's role

Even if your horse isn't showing any signs of illness, your vet may treat your horse prophylactically and may also want to submit the beetle carcasses and/or hay to a lab for toxin testing.
Questions Your Vet Might Ask:
  • Please describe the beetles.
  • Are the horses showing any signs of illness?
  • Do you think the horses ingested the beetles?

Diagnoses Your Vet May Consider

The cause of the problem. These are conditions or ailments that are the cause of the observations you make.

Very Common
more diagnoses

Author: Doug Thal DVM Dipl. ABVP