Haemorrhagic Diathesis in Neonatal Calves: An Emerging Syndrome in Europe

Abstract

In 2008 and 2009 a large number of cases of haemorrhagic diathesis (HD) in neonatal calves were reported in different European countries. In Flanders, 84 cases of neonatal HD in 30 herds were reported in this period. The disease typically affects calves younger than 1 month old from different breed and gender. Prominent clinical signs are cutaneous bleeding, petechiae on all mucosae, melena and often high fever. Early in the disease, the mental state of the animals is uncompromised. The typical haematological finding is pancytopenia, with severe to complete thrombocytopenia being the cause of the increased susceptibility to bleeding. In seven of the affected herds blood samples of calves of the same age group as the clinical case were collected and on six of those farms at least one subclinical case could be identified. Necropsy findings were generalized petechiae, ecchymoses or haemorrhages and variable lymphadenopathy. Histopathology of haemorrhagic lesions revealed multifocal extravasation of red blood cells (haemorrhage) with preservation of tissue architecture and absence of other abnormalities. Total bone marrow aplasia and depletion of all lymphoid tissue was the most prominent finding on histology. Activated macrophages and haemophagocytosis were seen on bone marrow cytology from two live calves. Polymerase chain reaction for bovine viral diarrhoea virus, bluetongue and epizootic haemorrhagic disease virus was negative. Several attempts to isolate a viral agent were unsuccessful.

Alloantibodies against MHC Class I: A Novel Mechanism of Neonatal Pancytopenia Linked to Vaccination

“…calves has been reported in several European countries (1)(2)(3)(4) and has been designated as bovine neonatal pancytopenia (BNP). The disease is characterized by severe thrombocytopenia and leukopenia-essentially a strong neutropenia and a mild lymphopenia-in 2-to 3-wk-old calves and in most cases leads to hemorrhages and a fatal issue.…”

The risks of using allogeneic cell lines for vaccine production: the example of Bovine Neonatal Pancytopenia

“…Hematology from BNP cases reveals a profound thrombocytopenia and leukopenia [2,13] and histopathology of bone marrow shows extensive depletion of hematopoietic cells (Figure 1). Experimental studies reproducing the disease demonstrated that as early as 4 h following ingestion of alloantibodies there is already a 75-95% reduction in peripheral blood lymphocytes, monocytes and neutrophils [16,17].…”

“…Rapid internal bleeding can result in affected calves being found dead with no external signs of hemorrhage, contributing to the under-reporting of cases [4]. Intercurrent infections are common and often result in profound pyrexia [2,13,15]. The majority (80-90%) of clinically affected calves die or are euthanized soon after the onset of symptoms [2,13], however in some cases recovery from the condition is possible [2,13].…”

“…Calves affected by BNP show no abnormalities at birth, their mothers are unaffected and there is no increase in abortion rate in affected herds [1,2,13]. Onset of clinical disease is usually between 7 and 28 days of age with signs of external and internal hemorrhage and petechiation [1,2,13,14].…”

“…Onset of clinical disease is usually between 7 and 28 days of age with signs of external and internal hemorrhage and petechiation [1,2,13,14]. Rapid internal bleeding can result in affected calves being found dead with no external signs of hemorrhage, contributing to the under-reporting of cases [4].…”