Fatty liver hemorrhagic syndrome (also referred to as fatty liver syndrome or FLHS), a

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

in chickens and other birds. Birds with this disease have large amounts of fat deposited in their liver and abdomen."Fatty Liver Syndrome: Introduction," ''Merck Veterinary Manual Online, 8th Edition, 2003. Retrieved fro
Merckvetmanual.com
on 2007-03-10. This often results in an enlarged

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...

that is easily damaged and prone to bleeding."Poultry: Causes for Fatty Liver Hemorrhagic Syndrome," ''Mississippi State University Extension Service''. Retrieved fro
Msucares.com
on 2007-03-11. In some cases the disease is

fatal Fatal may refer to: * ''Fatal'' (album), by Hussein Fatal, 2002 * ''Fatal'' (film), a 2010 French film starring Michaël Youn and Stéphane Rousseau * '' F.A.T.A.L.'', a tabletop role-playing game released in 2003 * Fatal Recordings, a record ...

, usually as a result of

blood loss Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...

from an internal

hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...

in the liver."Miscellaneous Management Related Diseases," ''Cooperative Extension Service: Mississippi State University''. Retrieved fro
Msstate.edu
on 2007-03-11. The hemorrhage often occurs when a hen is straining to lay her egg. Fatty liver hemorrhagic syndrome is "the major cause of mortality in laying hens."

Causes

Excessive dietary energy intake is believed to be the cause of fatty liver hemorrhagic syndrome. Heredity may also play a role, but it is not the entire cause for the disease. Birds housed in

cage A cage is an enclosure often made of mesh, bars, or wires, used to confine, contain or protect something or someone. A cage can serve many purposes, including keeping an animal or person in captivity, capturing an animal or person, and displayin ...

s will more likely be affected because they are unable to exercise to burn off the extra dietary energy. A 2019 study showed 74% of caged hens died from FLHS whereas only 0–5% of mortalities in hens from cage-free barn or free-range systems were attributed to this condition. Walking hens are less likely to develop this problem. The disease is observed most often in birds that appear to be

healthy Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organiz ...

and in a state of high egg production. As a result, death can occur quite unexpectedly.

Symptoms

Affected birds are usually overweight and may also have pale combs. Generally, however, the disease has few or no symptoms prior to the bird's death."Death Occurring In Fowl," ''GameRooster.Com Disease Diagnostics Aid''. Retrieved fro
Gamerooster.com
on 2007-03-11.

Treatment

The use of

L-Tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an Alpha_and_beta_carbon , α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with ...

in the diet can decrease the syndrome.Y. Akiba et al, L-Tryptophan alleviates fatty liver and modifies hepatic microsomal mixed function oxidase in laying hens, 1992, Comp. Biochem. Physiol. Vol 102A, N°4, pp 769-774.

References

{{reflist, 1 Bird diseases Poultry diseases