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Fatty Liver Disease

Other Names: Hepatic Steatosis, Fatty Liver Haemorrhagic Syndrome, FLHS

Fatty liver disease is a lipid metabolism disorder which is a common cause of death in backyard and commercial laying hens. The disease is characterized by excessive accumulation of fat deposits in the liver and abdominal cavity, along with a hemorrhagic and fragile liver. FLS in hens closely resembles nonalcoholic fatty liver disease (NAFLD) in humans. As such, chickens are used as the equivalent "animal model" for NAFLD research.

The lymphatic system of a chicken is rudimentary, meaning that the liver is the first organ to be exposed to dietary lipids (i.e. adipose tissue). This is where synthesis and metabolism of lipids occurs. This differs from mammals, where the majority of fatty acid synthesis occurs in adipose tissue, not the liver. Lipogenesis in the chicken liver is high, and particularly active in females who are producing eggs. Hepatic lipogenesis is dramatically enhanced by oestrogens in order to meet the demand for vitellogenesis.

Clinical Signs of Fatty Liver Disease

Clinical signs include both nonspecific and liver disease associated. The most commonly reported clinical signs include an obese body condition score, pale comb, dull feathers, and excessive toenail growth.
Other, nonspecific signs include lethargy, increased water consumption, and dyspnea. There is a strong seasonal influence with the onset of fatty liver syndrome in hens. Hens are more at risk of dying from fatty liver syndrome during warm weather conditions.

Clinical Signs

Over weight
Pale or shrunken comb
Dandruff on comb
Abnormally long beak or nail growth
Increased water consumption
Dull feathers or changes in feather color
Change in behavior


  • History
  • Clinical signs
  • Physical exam
  • Histology - Hepatic lipidosis with hemorrhage, sometimes reticulolysis.
  • Necropsy gross lesions - Enlarged, friable, soft livers that vary in color from pale tan to yellow to orange.
  • Liver panel

Reported Cases

  • Case 1: Fatty liver hemorrhagic syndrome in a Hen Fatty liver hemorrhagic syndrome (FLHS) was the cause of death of a 1-year-old, backyard brown hen. The bird was in lay and apparently healthy before death. At necropsy, there were large accumulations of fat in the coelomic cavity, a large blood clot on the liver, and multiple subcapsular liver hemorrhages. The liver was very pale and friable and prone to break. Ref

  • Case 2: Fatty liver hemorrhagic syndrome in a Hen A dead one-year-old female Red Sex-Link chicken was presented to the Texas A&M Veterinary Medical Diagnostic Laboratory in Gonzales, Texas for necropsy examination. Clinical history noted that the bird was found dead with no previous clinical illness noticed. They were fed an organic layer feed, vegetables, and fruit. History also noted the bird had no vaccinations or treatments and lived in a coop and run, i.e. not free range. On necropsy examination, the bird weighed 2.35 kilograms and no external abnormalities were noted. Upon opening the coelomic cavity, a large blood clot was present overlying one liver lobe. The underlying liver had a rupture in its capsule which was the source of the blood clot. Numerous smaller blood clots were observed under the capsular surface of the other liver lobe. The liver was pale orange in color, was friable, and had a “greasy” texture (fatty liver). The fat pad in the distal coelomic cavity was very large and the bird was in full production and had a shelled egg in the distal oviduct. No lesions were noted in any other tissue or organ system. Ref


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Milk thistle (Silybum marianum)400 mg/kg of feed helps provide liver protection.S Romanelli et al., 2016; M Saeed et al., 2017; A Baradaran et al., 2019
Genistein40-400 mg/kg diet significantly decreased the serum ALT, creatinine, triglyceride (TG), total cholesterol (TC), and free fatty acid (FFA) levels, resulting in alleviation of metabolic disorder and inflammatory responses in FLS hens.Z Lv et al., 2018
FlaxFeeding supplemental flaxseed, flax oil, or Omega 3 fatty acids helped attenuate the progression of FLS in hens.J Davis et al., 2016; G Masterton et al., 2010
Bai Zhu (Atractylodes macrocephala Koidz)When added to the diet of laying hens at 200-400 mg/kg, one study found that it helped ameliorate liver injury through regulating activities of antioxidant enzymes and hepatic lipid metabolism.Y Miao et al., 2021
Resveratrol400 mg/kg effectively attenuates oxidative stress and inflammation in hens with fatty liver syndromeX Wang et al., 2019; M Rubio-Ruiz et al., 2019; C Xing et al., 2020
LycopeneWhen added to the diet of laying hens at 20-80 mg/kg it can help regulate fat metabolism in hens and mice.H Tian et al., 2020; N Yinhua et al., 2020



  • Keep feed crude protein level above 17.5% from a quality protein source. Ensure fat content is less than 3.5%.
  • Don't give excessive amounts of scratch or foods with high sugar content such as grapes.
  • Ensure hens are receiving adequate daily exercise
  • Provide supplemental antioxidants and Vitamin B.



Scientific References


Age Range

Occurs most often in obese, adult hens.

Risk Factors

  • Feeding hens excessive amounts of scratch or other high-sugar foods such as grapes.
  • Overweight hens
  • White-egg layers
  • Unbalanced diet
  • Feeding hens a low-protein high-energy (HELP) diet
  • Antioxidant (such as vitamin E) deficiency
  • Copper deficiency
  • Moldy feed
  • Toxin exposure
  • Metabolic diseases such as thyroid dysfunction.

Case Stories