Equine cantharidiasis usually results from ingestion of alfalfa hay co
ntaminated with blister beetles that contain the toxin cantharidin. Al
though clinical signs of the condition vary greatly, gastrointestinal
disturbances, pollakiuria, and evidence of hypocalcemia are frequently
evident. Consistent laboratory findings include low urine specific gr
avity despite hemoconcentration, hypocalcemia, hypomagesemia, mild azo
temia, and elevations in serum creatine kinase values. Early supportiv
e therapy is indicated and consists of decontamination and evacuation
of the gastrointestinal tract, intravenous balanced electrolyte soluti
ons. calcium supplementation, and gastrointestinal protectants. Urinar
y cantharidin assay via gas chromatography-mass spectrometry or high-p
ressure liquid chromatography can provide antemortem diagnostic confir
mation of the condition. Significant necropsy lesions include enteroco
litis, cystitis, and myocardial necrosis. Vesiculating gastropathy of
the squamous mucosa (caused by the specific acantholytic effect of can
tharidin) is a highly diagnostic finding.