Lymphoid Leukosis – Avian (The Wasting Disease)
by the Cuckoo Stud

Written after research and consultation with a retired Avian Scientist and comparisons with other breeders who have also experienced this problem after acquiring new birds.

​This is here only as a reference as the incidence of people selling chicks/birds hatched from pullet eggs AND selling pullet eggs is on the rise =
no apologies given if any wording in this article offends anyone

Lymphoid Leukosis is becoming a common cause of death in birds as so many now use pullet eggs and then sell or give away the chicks without advising the new owner that the mother is a pullet.

If you hatch a chick from a juvenile female =
I wont say hen as they are not until they have experienced their 1st moult - and if that line has L.L. in it  (admittedly not everyone knows that their bird is an L.L. carrier) there is a very high risk of the pullet passing on the L.L. to most if not all of the offspring.
​
Then the new owner gets to know this/these new bird/s and starts to love them, then the bird/s get 'sick' - meaning they actually arrived sick but only displayed the disease later due to the slow progression = a VERY upset person

The incidence of passing L.L. on after the 1st moult reduces by about 95% and reduces to almost zero after the 2nd moult
# meaning some hens will continue to pass L.L. via the egg but at a reduced incidence

Now = not many breeders will admit they have L.L. in their lines (IF they even know) OR that the mother bird is a pullet =
so it is very sad that it is a Russian Roulette when you get a new young bird or eggs.

A suggestion to all = only get birds/eggs from people that use hens as breeders = that have gone thru their 1st but preferably
their 2nd moult .
If you are unsure = go elsewhere. And only use hens to breed from.
​
The need to reduce L.L. ought to be a high priority but until people stop breeding from pullets and have patience for the bird to moult this is going to continue.

Lymphoid Leukosis - The Disease -

Avian Lymphoid Leukosis is a neoplastic disease of chickens caused by a virus of the Leukosis/Sarcoma group and is characterised by tumour formation of the Bursa of Fabricius with Metastasis to other tissues and all abdominal organs.

Symptoms of Lymphoid Leukosis :-

Emaciation     -    loss of weight    -    depression like behaviour    -    persistent low mortality in flock    -

enlargement of liver, bursa, abdomen    -    many affected birds are Asymptomatic


Manifestations :-

Lymphoid Leukosis,  Myeloid Leukosis (Granuloblastosis, Myeloblastosis),  Erythroid Leukosis [Erythrolastosis], Hemangioendothelioma (tumours comprised of blood vessels) and Osteopetrosis (Bone Leucosis).


Susceptibility starts in Ova but usually decreases with the age of the bird. Occasionally an older bird (1+ years) will fall to L.L. and should not be mistaken for Latent Mareks in the older bird.

Birds are most susceptible while still young (under 1yr of age).

Pullets are more susceptible than cockerels to all forms of L.L. except Osteopetrosis, to which the cockerel is much more susceptible.
Stresses caused from other diseases increases the severity of the Leukosis. As the ‘virus’ has a long incubation period signs
are most often not noticeable until birds are 16 weeks or older. Making it important to delineate L.L. from Mareks

The disease produces progressive weakness, regression of comb, paleness, enlarged abdomen, emaciation and death.
Greenish diarrhoea develops in terminal stages.

Diagnosis based on flock history and tumours is usually confirmed by typical progression of the disease and differentiation
from other diseases. There is no treatment.

Prevention is to obtain chicks from L.L. free sources, or chicks hatched from hen eggs not pullet eggs.
Raise the birds in isolation with adequate ventilation and bio-security, prevention of stress where possible and the control of other diseases.

Most exhibition breeders recommend not to use pullet eggs to help reduce the incidence of L.L.

The risk of L.L. is less than 5% in chicks hatched from hen eggs (after the birds have experienced the first moult)
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note however that up to 5% of hens that carry L.L. will continue to pass it on via the egg = careful selective breeding, marking each hens offspring and growing out of all chicks to 11months old to determine if any hen/s does/do still pass on L.L. is
essential to help eradicate the disease from your flock

# L.L. is not known to be passed via the sperm of either the cockerel or rooster that displays no symptoms or survives L.L.

# published 2004 - subject to copyright laws of Australia