Fatty Liver Hemorrhagic Syndrome (FLHS) in Laying Hens
Clinical guide covering hepatic lipidosis, liver parenchymal rupture, pale comb sudden death, Choline Chloride, and Vitamin E therapy.
Scientific Overview
Fatty Liver Hemorrhagic Syndrome (FLHS) is a metabolic disorder affecting high-producing cage-housed laying hens and breeder stock. Characterized by excessive hepatic lipid accumulation (hepatic steatosis) followed by liver capsule rupture and fatal intra-abdominal hemorrhage, FLHS is a major non-infectious cause of layer flock mortality.
Metabolic Etiology & Hepatic Lipidosis
Fatty Liver Hemorrhagic Syndrome (FLHS) is defined as a metabolic disorder where positive energy balance causes extreme fat accumulation in hepatocytes, weakening hepatic structural parenchyma.
Estrogen during peak lay stimulates hepatic lipogenesis. High-calorie diets, warm temperatures, and lack of exercise accelerate fat infiltration until minor abdominal pressure triggers liver rupture.
Necropsy Pathology & Sudden Death
Key clinical findings at post-mortem:
- Pale Comb & Sudden Mortality: Birds in peak production (>85% lay) are found dead with pale combs and wattles.
- Friable Yellow Liver: The liver is enlarged, pale yellow, extremely greasy, and soft.
- Abdominal Blood Clot: Large gelatinous red hematomas fill the peritoneal cavity, originating from a tear in the liver capsule.
Nutritional Therapy & Prevention
Prevent FLHS by balancing dietary energy-to-protein ratios and supplementing lipotropic agents in feed: Choline Chloride (1,000 mg/kg), Vitamin E (50 IU/kg), Vitamin B12, and Inositol to promote hepatic lipid export.
All scientific data, diagnostic criteria, and performance benchmarks presented on this page are derived from published peer-reviewed journals and official veterinary codes:
- Avian Pathology & Diagnostics: World Organisation for Animal Health (WOAH, 2023). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. Paris, France.
- Poultry Diseases & Histology: Swayne, D.E., et al. (2020). Diseases of Poultry (14th ed.). Wiley-Blackwell / American Association of Avian Pathologists.
- Nutrition & Feed Chemistry: Leeson, S. & Summers, J.D. (2001). Commercial Poultry Nutrition (3rd ed.). University Books, Guelph, Ontario.
- Commercial Breed Standards: Aviagen (2024). Ross 308 & Cobb 500 Broiler Performance Objectives. / Lohmann Breeders (2024). Lohmann Brown Management Guide.