First report of fatty liver haemorrhagic syndrome (FLHS) in layer chicken population of Assam

Abstract

Fatty Liver Haemorrhagic Syndrome (FLHS) is a non-infectious, nutritional and metabolic disorder primarily affecting laying hens, resulting in significant production losses due to reduced egg output and increased mortality. This study presents the first confirmed outbreak of FLHS in a layer chicken population in Assam, India. The investigation was carried out from July to August 2024 in an organized farm housing 487 BV-380 birds, where 28 birds (5.74%) died exhibiting signs consistent with FLHS. Clinical observations recorded by the farm manager included inappetence, dullness, depression, and pale combs and wattles. Necropsy revealed hepatomegaly with greasy, friable livers ranging from grayish-yellow to orange in color, petechial to ecchymotic haemorrhages, haematomas, hepatic rupture, pale musculature, and extensive fat accumulation in the abdominal cavity. Histopathological findings supported the diagnosis, showing vacuolar degeneration in hepatocytes, with fat globules of variable size, pyknotic nuclei, displacement of nuclei, and sinusoidal haemorrhages. The presence of pale muscles, observed grossly, was an unusual finding not commonly reported in literature. This case highlights the pathological features and diagnostic indicators of FLHS in actively laying hens and suggests that hormonal, dietary, and environmental stressors might contribute to its manifestation. Regular monitoring and nutritional management are critical to prevent and mitigate such outbreaks.