VIRAL DISEASES
A COLOUR ATLAS OF POULTRY DISEASES
seen at one week of age. The muscular incoordination varies from slight incoordination to sitting on the hocks, or lying down on one side (Fig. 45). The birds are unable to move. In such a condition , death occurs from not reaching to the feed (starvation), or getting crushed by other members of the flock. Birds over 4 weeks of age rarely show avian encephalomyelitis. 2.
In layers, there is some drop of egg production , with reduced hatchability.
3.
Very mildly affected birds recover completely.
Postmortem Findings There are no gross lesions (changes) in the young or older birds. Therefore, the disease cannot be diagnosed from postmortem .
Diagnosis I.
The symptoms in young birds, absence of gross changes at postmortem together with the absence of other infectious and nutritional deficiencies affecting the nervous system, are strongly suggestive of avian encephalomyelitis.
2.
However, a definitive diagnosis requires help of laboratory tests.
3.
In differential diagnosis, it is necessary to rule out vitamin E deficiency (nutritional encephalomalacia; see 'vitamin E deficiency').
Treatment Treatment is of no value.
Control I.
Under commercial conditions, it is not possible to eliminate infection by high standards of hygiene alone. Thus, control depends on the vaccination of birds, and using hatchery eggs from breeder flocks that are free from avian encephalomyelitis.
2.
Live and killed vaccines can be given which produce a lasting and adequate degree of protection .
Fig. 45 . Muscular incoordination and recumbent (lying down) position of chicks. This may be due to avian encephalomyelitis. or deficiency of vitamin A, or E.
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