Calf-Level Factors Associated with Bovine Neonatal Pancytopenia – A Multi-Country Case-Control Study

Jones, Bryony A.; Sauter-Louis, Carola; Henning, Joerg; Stoll, Alexander; Nielen, Mirjam; Van Schaik, Gerdien; Smolenaars, Anja; Schouten, Matthijs; den Uijl, Ingrid; Fourichon, Christine; Guatteo, Raphael; Madouasse, Aurélien; Nusinovici, Simon; Deprez, Piet; De Vliegher, Sarne; Laureyns, Jozef; Booth, Richard; Cardwell, Jackie M.; Pfeiffer, Dirk U.

Bovine neonatal pancytopenia (BNP) was first reported in 2007 in Germany and subsequently observed at low incidence in several other European countries and New Zealand [1] [2] [3] [4] . It affects calves aged up to 4 weeks, causing skin and internal haemorrhages, prolonged haemorrhage from wounds or orifices, and high case fatality (90%) [5] [6] [7] . No evidence of an infectious, toxic or genetic aetiology has been found [2, [5] [6] [7] . In 2010 an association was suspected between affected calves and vaccination of their dams with PregSureHBVD (PregSure, Pfizer Animal Health) [8] . BNP was induced experimentally by feeding calves colostrum from unrelated PregSure-vaccinated dams that had previously given birth to BNP calves [9] . It was hypothesized that maternal antibodies in colostrum were destroying calf blood and bone marrow cells. PregSure is an inactivated bovine viral diarrhoea (BVD) virus type 1 vaccine, which was first marketed in 2004 [10] . The manufacturer, Pfizer Animal Health, voluntarily stopped sales to wholesalers in Europe in 2010, and New Zealand in 2011, pending investigations into the cause of BNP. The marketing authorisations in all concerned European Union (EU) Member States were suspended in August 2010 following an EU Commission decision based on recommendations from the European Medicines Agency Committee for Veterinary Medicinal Products (CVMP), with recall of product at wholesale level [11] . By the end of August 2012, 6913 suspected BNP cases had been reported by farmers, veterinarians and laboratories via the pharmacovigilance system in each European member state to the marketing authorization holder, Pfizer Animal Health. The numbers of reported suspected cases decreased in 2011 and 2012 compared with previous years. This case-control study was conducted to identify potential risk factors for BNP occurrence at the calf level.