Bleeding disorders in calves

WE wish to highlight the occurrence of a bleeding disorder in calves clinically and histopathologically indistinguishable from bovine neonatal pancytopenia (BNP), where there is no possibility of ingestion of colostrum derived from PregSure-vaccinated cattle. BNP was first recognised as a clinicopathological entity in Europe in 2007 (Bastian and others 2011) and in the UK in 2009 (Penny and others 2009), defined as a haemorrhagic disease occurring in calves less than 28 days of age and involving bone marrow lesions of trilineage hypoplasia (severe depletion of all three main haematopoietic cell lineages) (Lambton and others 2012). It has been diagnosed in calves of many breeds between one and four weeks of age, and a strong association has been demonstrated with vaccination of the dam with the bovine viral diarrhoea virus (BVDV) vaccine PregSure (Lambton and others 2012, Sauter-Louis and others 2012). Field and experimental data strongly suggest the pathogenesis involves colostral alloantibody-mediated destruction of haematopoietic progenitor cells in bone marrow. This results in cytopenias, including thrombocytopenia, and hence bleeding. BNP is still being diagnosed despite the withdrawal of the PregSure vaccine in 2010, both in calves born to PregSure-vaccinated cows that have previously had affected calves, but also in calves born to cows that previously raised …