Tips on Fatty Liver Hemorrhagic Syndrome


As there is an association between fatty liver hemorrhagic syndrome (FLHS) and poor egg shell quality, with this article, Zucami’s technical team intends to present TIPS that will help our customers to know and identify the disease.

Fatty Liver Hemorrhagic Syndrome (FLHS) is a non-infectious disease that appears mainly in laying hens.

It is a disease characterized by an excess accumulation of fat in the abdominal cavity and liver, which leads to liver rupture, hemorrhage and sudden death.

What is fatty liver hemorrhagic syndrome or FLHS?

FLHS or fatty liver hemorrhagic syndrome is characterized by a drop in egg production (hens in affected flocks are generally obese and experience a sudden drop in egg production) and sudden death (mortality is usually 3-5%, but higher mortality rates have been reported).

Affected hens usually have pale chins, ridges and skin and a large amount of fat in the liver found during necropsy

FLHS and shell quality.

To activate vitamin D in its metabolically active form, is one of the most important functions of the liver.

Therefore, if the organ is affected, there may be an interference with the formation of active Vitamin D, which may lead to an increase in serum calcium levels in FLHS birds, affecting the eggshell formation process.

The first changes in the liver can already be noticed at the beginning of the reproductive period and are related to the increased synthesis of lipids and proteins destined for the egg yolk.

Any factor that decreases liver function will negatively impact laying index and egg quality. On top of that, it will also increase the likelihood that animals will suffer from infections due to immune effector deficiency.

FLHS, multifactorial syndrome.

The exact cause of FLHS or fatty liver hemorrhagic syndrome is unknown. It is estimated that a combination of factors such as nutrition, genetics, environment and hormonal influence may cause this syndrome.

Risk factors have been described as:

Energy balance and body weight:

The most important factor currently described in the sources we have consulted appears to be excess energy intake.

Estrogen predisposes the batch to FLHS:

Estrogen hormone is associated with sexual maturity and stimulates the liver to store more fat for egg yolk synthesis.

Heat stress:

The high incidence of FLHS occurs during warm periods. High ambient temperatures reduce energy requirements, and lead to a more positive energy balance.


Mycotoxins, especially aflatoxins, can contaminate cereals, inducing lipid accumulation in the liver and hepatic hemorrhages.

FLHS prevention.

We must check body weight and flock uniformity to discover those hens that have excess body weight; less uniform flocks (with more obese hens) are at higher risk of developing fatty liver syndrome.

Decreased egg production, mortality and weight gain are important aspects that should be monitored to prevent the onset of the syndrome.

Necropsies are also recommended to evaluate excess fat in the abdominal region and the condition of the liver.

Fatty Liver Hemorrhagic Syndrome (FLHS) is a non-infectious disease that appears mainly in laying hens.


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