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Fatty Liver Disease

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

Fatty liver disease (FLD), also known as fatty liver syndrome, is a metabolic disorder and a leading cause of mortality in laying hens worldwide. It is marked by excessive fat accumulation within the liver and abdominal cavity, which can result in liver rupture, internal hemorrhage, and sudden death.

Chickens are particularly prone to this condition due to the structure of their lymphatic system, which favors fat deposition in the liver. Actively laying hens face an even higher risk because elevated estrogen levels associated with egg production promote fat metabolism and storage in the liver.

This natural predisposition is one reason chickens—especially hens—are frequently used as animal models for studying nonalcoholic fatty liver disease (NAFLD) in humans. FLD in chickens is characterized by hyperlipidemia similar to dyslipidemia seen in steatohepatitis in humans.

Clinical Signs of Fatty Liver Disease

Hens affected by fatty liver disease are often found dead with pale facial skin, comb, and wattles due to internal bleeding.

Commonly reported signs include obesity, poor feather quality, and overgrown toenails. Other nonspecific signs may include lethargy, increased water intake, and difficulty breathing.

Clinical Signs

Sudden death

Obesity

Pale face, comb and wattles

Dandruff on comb

Lethargy

Abnormally long beak or nail growth

Increased water consumption

Dull feathers or changes in feather color

Change in behavior

Diagnosis

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

Treatment

Name	Summary
Supportive care	Isolate 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.
Diet changes	Cut back on treats, especially scratch, corn and grapes. Consider switching to corn-free feed.
Milk thistle (Silybum marianum)	Effectively protected the liver from lipid accumulation and severe hepatic changes in rats with nonalcoholic fatty liver disease and type 2 diabetes. In humans it improved the ultrasound fatty liver grading and liver enzymes.	S Mirhashemi 2022; A Doostkam 2022
Genistein	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 hens with fatty liver disease.	Z Lv et al., 2018
Flax	Feeding supplemental flaxseed, flax oil, or Omega 3 fatty acids helped attenuate the progression of fatty liver disease in hens.	J Davis et al., 2016; G Masterton et al., 2010
Bai Zhu (Atractylodes macrocephala Koidz)	Helped ameliorate diet-induced liver injury through regulating activities of antioxidant enzymes and hepatic lipid metabolism in hens with fatty liver disease.	Y Miao et al., 2021
Resveratrol	Effectively attenuated oxidative stress and inflammation in hens with fatty liver disease.	X Wang et al., 2019; M Rubio-Ruiz et al., 2019; C Xing et al., 2020
Lycopene	Alleviated excessive hepatic lipid accumulation, enhanced lipolysis, and decreased serum lipids levels in chickens and mice.	H Tian et al., 2020; N Yinhua et al., 2020

Support

Prevention

Maintain a balanced diet with crude protein levels above 17.5% from high-quality sources, while keeping fat content below 3.5%
Avoid feeding excessive scratch grains or high-sugar treats such as grapes
Encourage regular activity to prevent obesity
Consider supplementing with antioxidants and B vitamins.
Providing a cool environment during hot weather