Avian Lymphoid Leukosis (LL) in Lay ...

Avian Lymphoid Leukosis (LL) in Laying Hens

Avian Lymphoid Leukosis (LL) in Laying Hens

Observed Clinical Signs Happenings

Visibly sick birds

  • Few visibly sick birds
  • Weakness
  • Inappetance
  • Dehydration

Mortality

  • Low mortality or increases gradually
  • Birds die within a few weeks
  • Other affected birds may die without showing obvious signs

Dead birds

  • Poor bodily  condition
  • After clinical signs develop, the course of the disease is usually rapid, and birds die within a few weeks. Other affected  birds may die without showing obvious signs

Droppings

  • Diarrhea
  • In some instances or sometimes it is difficult to observe diarrhea in live birds but generally, the dead birds may show diarrhea signs

Head Comb Wattles Face Nostrils Sinuses Mount Beak Earlobes

  • The comb may be pale
  • Comb shrivelled
  • Comb occasionally cyanotic

Body Parts (Neck, wings, breast, abdomen, shanks, legs, hocks, feet, joints, vent, and skin, abnormalities), skinny body, retarded growth, weight depression

  • Abdominal enlargement
  • Emaciation
  • skinny body
  • Dehydration

Feather Abnormalities

  • In erythroblastosis and myeloblastosis, haemorrhage from feather follicles also may occur

Avian Lymphoid Leukosis (LL) in Laying Hens show, exhibit, or manifest any of the following clinical signs happenings:

Observed Clinical Signs Happenings

ALWAYS

NEVER

SOMETIMES*

Egg drop

 

  •  

 

Mortality above the standard

  •  

 

 

Low mortality or increases gradually

  •  

 

 

High mortality or increases rapidly

 

  •  

 

Dead birds

  •  

 

 

Dead birds in Good bodily condition

 

  •  

 

Dead birds in Poor bodily  condition

  •  

 

 

Visibly sick birds

  •  

 

 

Few visibly sick birds

  •  

 

 

Many visibly sick birds

 

  •  

 

Flock behaviour activity change

 

  •  

 

Droppings abnormalities

  •  

 

  •  

Respiratory abnormalities

 

  •  

 

Neurological Nervous

 

  •  

 

Lameness or unusual movements, incoordination, reluctance to move

 

  •  

 

Eyes abnormalities

 

  •  

 

Head: Comb Wattles Face Nostrils Sinuses Mount Beak Earlobes (except eyes)

  •  

 

 

Body Parts (Neck, wings, breast, abdomen, shanks, legs, hocks, feet, joints, vent, and skin, abnormalities), skinny body, retarded growth, weight depression

  •  

 

 

Feathers abnormalities

  •  

 

  •  

Feed Consumption Changes

 

  •  

 

Diet or Feed Changes (Recent Feed delivery, Recent formulation /diet, Other silo or improper storage, another feed brand)

 

  •  

 

Shell quality

 

  •  

 

Internal Egg quality

 

  •  

 

*Sometimes has not been observed the Droppings abnormalities (diarrhea) yet or depend on the course time of the disease

*Sometimes has not been observed the Feathers abnormalities (Erythroblastosis and Myeloblastosis)) yet or depend on the course time of the disease

 

 

 

Causing Agents
Viral disease. Virus (Retroviridae family), Neoplastic Disease. Lymphoid Leukosis. These are the oncogenic virus (otherwise known as oncoviruses or tumor viruses).
Affected Systems/Organs
Tumors invariably involved: Bursa. Liver. Spleen, Kidney and others visceral organs.
Spread
Congenital (from parents) transmission is most important. Bird to bird transmission is poor but infection may occur through the feacal oral route.
Mainly Affects
Liveability
Solution
Biosecurity, all-in/all-out production system. Control arthropods. Hygiene.
Suggested Actions
  • Can be confirmed with clinical signs and gross lesions
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended

Impact on Egg quality

0

Impact on Liveability

2


Impact on Production

0

Overall Economic Impact

1



  1. Y.M. Saif.2008.Disease of Poultry. 12th Edition.page 531
  2. David E. Swayne. 2013.  Diseases of Poultry 13th Edition. page 570
  3. Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition. 284

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