Peripartum heart disease in cows.

Thirteen Holstein dairy cows aged 5.1-10.6 years died or were killed as a result of severe illness during the peripartum period, associated with lateral recumbency, moaning, tachycardia and dyspnoea. They were all high milk producers (> 9000 kg/year) and had experienced at least three pregnancies. The average duration of the clinical course was 2.5 +/- 1.7 days. Electro-cardiography revealed marked tachycardia associated with atrial fibrillation or atrioventricular dissociation. Serum clinical chemistry showed severe hypocalcaemia (3.6 +/- 1.3 mg/dl) and at necropsy multifocal myocardial necrosis was invariably found. Myocardial necrosis was accompanied by neutrophilic and mononuclear cellular infiltrates with interstitial fibrosis. The cause of this lesion was not established.