Cantharidin, the highly toxic substance found in blister beetles, can cause severe complications and death if ingested by your horse. Blister beetles swarm in alfalfa fields and can accidentally end up in hay bales. The best way to avoid the deadly pests is to check your hay for their presence—dead or alive. Blister beetle poisoning is a red-alert emergency and requires immediate veterinary care. Signs that your horse may be suffering from blister beetle toxicity include:
• Blisters in the mouth and on the tongue
• Salivation (usually due to blisters)
• Goes off feed
• Increased heart and respiratory rates
• Sweating
• Fever
• Colic
• Diarrhea
• Endotoxic shock (indicated by discolored gums)
• Blood in manure or urine
• Thumps (referred to as synchronous diaphragmatic flutter; can look like hiccups)