PATHOLOGICAL STUDIES OF ENTERO-HEPATIC AFFECTIONS IN DUCKS AND SCREENING FOR SPECIFIC VIRAL ETIOLOGY
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Date
2019-10-03
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD
Abstract
Duck production holds an important position in the Indian poultry scenario,
being the second most domesticated species of poultry in the country after chicken.
Ducks are reared for both meat and egg production and a healthy liver and intestine
capacitate the bird for its best performance and help the farmers for better
profitability. Reports on systematic studies on the liver and intestinal lesions of
ducks are scanty in India or have only been studied in relation to particular disease
aetiology. Even though ducks show less susceptibility to diseases compared to the
chicken, a few infectious and non-infectious diseases that affects liver and intestine
were reported in ducks from many duck rearing countries. Among the viral
diseases, the most important infections reported are duck enteritis virus (DEV) and
duck virus hepatitis (DVH). Duck virus hepatitis (DVH) is an acute and contagious
disease affecting liver but so far has not been reported in India. The present study
was aimed at systematic post mortem recording of gross and histopathological
lesions in the liver and intestine of duck carcasses and screening for DVH viruses
and DEV by Polymerase chain reaction (PCR) using species specific primers. A
total of 112 duck carcasses were examined in the study. Liver showed enlargement
with characteristic deep yellow discoloration and firmness in 43.75 per cent cases.
Pale yellow or dark brown friable liver recorded in 21.43 per cent cases.
Amyloidosis of varying degrees were observed in 61.61 per cent cases of duck
livers examined. A correlation between the severity of amyloidosis and gross
lesions could also be derived. The enlarged, yellow and firm liver was observed to
have moderate to severe amyloidosis histologically, while pale pink liver had
moderate amyloidosis. The intestine also showed amyloid deposits in such cases
without appreciable gross lesions. Ducks farmed under intensive system of rearing
had a higher incidence of amyloidosis particularly in White Pekin ducks. Friable
consistency of liver was either due to severe congestion or fatty change.
Hepatocellular carcinoma with cirrhosis was identified in one case. DVE and DHV
were not detected in any of the cases. Further screening for DVH viruses in a larger population of ducks is warranted. The absence of DEV in the current study may be
due to effective control of the disease through appropriate vaccination strategies.
The high incidence of amyloidosis in this study and the possible risk of dietary
consumption of amyloid livers and its zoonotic potential needs to be investigated.