Natural aflatoxicosis in neonatal calves in a dairy herd – pathological diagnosis

Abstract

Aflatoxins have been known as an important cause of animal disease for 30 years. The toxins occur naturally on animal feeds either in the field or during storage when moisture content and temperatures are sufficiently high for mould growth. The present paper describes clinical signs besides of gross and histopathological features of aflatoxicosis in 2 to 5-day-old dairy calves which were infected naturally in February 2017. According to the history and clinical examinations, clinical signs included ano-rexia, ataxia, reluctance to move, convulsion and neonatal mortality in 2 to 5-day-old calves in this herd. Also, black mould as Aspergillus niger was observed in storage animal feeds especially in rouphage and silage. At necropsy, there was sanguineous ascites with multifocal haemorrhages under serosal and mucosal surfaces of gastrointestinal tract, mesenteric lymph nodes, kidneys, and men-inges. The liver and spleen were slightly enlarged and hyperaemic. Intramural oedema and haemor-rhage were seen in the wall of gall bladder. Histopathological examinations revealed haemorrhagic enteritis, abomasitis and nephritis. There were multifocal large extramedullary haematopoiesis espe-cially with accumulation of megakaryocytes in the liver and spleen. Moreover, the liver showed mild fatty changes in hepatocytes, centriacinar fibrosis with bile ductules proliferation. In the brain, there were perivascular and perineuronal oedema, and perivascular haemorrhage. According to these re-sults, it seems that calves in this herd suffered from hepatoencephalopathy due to simultaneous acute and subacute aflatoxicosis in which aflatoxins originally produced in animal feeds and transferred during pregnancy and also postnatally via milk, were the cause of neonatal mortality in the herd.

Keywords

• aflatoxin
• aspergillus niger
• pathomorphology
• hepatic fibrosis
• neonatal calves