Lymphoid leucosis is 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 ...

that affects chickens, caused by the retrovirus ''

Avian leukosis virus Avian sarcoma leukosis virus (ASLV) is an endogenous retrovirus that infects and can lead to cancer in chickens; experimentally it can infect other species of birds and mammals. ASLV replicates in chicken embryo fibroblasts, the cells that contr ...

''. It is a neoplastic disease caused by a virus, which may take the form of a

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

of the

bursa of Fabricius In birds, the bursa of Fabricius (Latin: ''bursa cloacalis'' or ''bursa fabricii'') is the site of hematopoiesis. It is a specialized organ that, as first demonstrated by Bruce Glick and later by Max Dale Cooper and Robert Good, is necessary fo ...

and may

metastasize Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, ...

to other tissues of the chicken and cause enlargement and swelling of the abdomen.

Symptoms

Symptoms include enlargement of abdomen, bursa,

weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat ( adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other co ...

weakness Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...

and

emaciation Emaciation is defined as the state of extreme thinness from absence of body fat and muscle wasting usually resulting from malnutrition. Characteristics In humans, the physical appearance of emaciation includes thinned limbs, pronounced and protrud ...

, and depression. The disease is more likely to affect chicken around five to eight months of age who are more vulnerable. Green

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin w ...

tends to develops at the terminal stage.

References

Bird diseases Animal viral diseases Alpharetroviruses {{veterinary-med-stub