2,3,6,7 Cantharidin may also cause hypocalcemia and its associated clinical effects including muscle fasciculations, synchronous diaphragmatic flutter, abnormal gait, dysphagia, and abnormal behavior such as aggressiveness or disorientation. 3,6,7 Sudden death with no signs of struggle has been reported. 3,6,7 Hypocalcemia and hypomagnesemia are consistent findings and can help differentiate cantharidin toxicosis from other causes of colic. 2,3,6,7 Other abnormal laboratory findings can include hypoproteinemia, azotemia, increased creatine kinase activity, hyposthenuria, and hematuria. Necropsy findings may include mucosal hyperemia, hemorrhage, edema, vesication, and ulceration anywhere within the gastrointestinal or urinary tract.
Some horses have myocardial necrosis.
Diagnosis can be confirmed by testing the urine and gastrointestinal contents for cantharidin. 3,6,7 Insect parts can sometimes be identified in gastrointestinal contents or feces. No antidote is available for blister beetle poisoning. All suspect alfalfa hay, cubes or pellets should be removed from the animal's diet. Administering activated charcoal and mineral oil may reduce toxin absorption.