Granulocytopaenia and thrombocytopaenia in dairy cattle--a suspected mycotoxicosis.

During a 6-week period, 22 Dairy Shorthorn cows and heifers died with granulocytopaenia and thrombocytopaenia. Clinical signs observed in the affected animals included increased salivation, pyrexia, depression, rumenal stasis, bilateral epistaxis, melaena, increased bleeding after removal of retained foetal membranes and rapid weight loss. Despite intensive antibiotic and vitamin K therapy and blood transfusions, all affected animals died. The aetiological agent, thought to be a fungal toxin, could not be isolated from post mortem specimens or pasture samples.