ijvp

Indian Journal of Veterinary Pathology

0250-47580973-970X

Indian Association of Veterinary Pathologists

ijvp-40-3-abs004

ABSTRACTS OF DISSERTATIONS OR ARTICLES

Clinico-pathological studies on Marek's Disease in chickens

Das

Supriya

¹Das

Debiprasanna

Dr.¹

¹Degree/Year: M.V.Sc/2015 Name of the University: Orissa University of Agriculture & Technology, BBSR, Odisha

192016

403295295

2016

IndianJournals.com

Marek′s Disease (MD) is a highly contagious oncogenic and neuropathic disease of chickens responsible for great economic losses to the poultry industry. In the present study, an attempt was made to diagnose MD in naturally infected chickens in organized poultry farms by evaluating clinicopathological findings such as clinical signs, haematology, gross lesions, cytological and histopathological observations in suspected neoplastic diseases. 174 representative tissue samples from various organs with tumorous lesions were collected from 62 suspected cases to carry out gross, cytological and histopathological examinations and 15 blood samples were collected from suspected live birds for haematological analysis. Based on gross, cytological and histopathological examinations, 25.80%, 38.70% and 43.54% of suspected cases could be diagnosed as Marek′s Disease respectively. All the cases were found in egg type birds of age group 20–30. The incidence is more in female birds (53, 85.48%) than in male birds (09, 14.52%). Affected birds had decreased breeding potential, reduced growth, inappetence, depression, lameness and skin nodular lesions. There was highly significant increase in TLC in affected cases. On necropsy, various sized gray to yellow tumor-like nodular lesions were found on visceral organs including liver, spleen, lungs, heart, kidney, ovaries, trachea, proventriculi and duodenum. The affected organs were enlarged, pale, friable and flabby. In some cases, unilateral or bilateral enlargement and edema of nerves particularly sciatic and brachial nerve with loss of cross striations was observed. Cutaneous form was characterized by nodular lesions at the base of feather follicles. The cytological examination of impression smears taken from affected tissues revealed lymphocytes with increased cellularity and pleomorphism having thin rim of cytoplasm and vesicular nucleus. Histopathologically, the liver sections revealed diffuse and focal infiltration of pleomorphic lymphoid cells including small, medium and large lymphocytes, lymphoblasts and reticulum cells. In diffuse type, the entire hepatic tissue was infiltrated by solid sheets of pleomorphic lymphoid cells compressing and obliterating the normal structure of the organ. Sections of spleen revealed depletion and degenartion of lymphocytes in and around germinal centres with lymphoplasmacytic infiltration and oedema. The sections of ovary exhibited extreme infiltration and aggregation of pleomorphic lymphocytes displacing the entire ovarian tissue and only a few scattered follicles were discerned. Peripheral nerve sections showed neoplastic pleomorphic lymphoid cell infiltration with mononuclear cells and plasma cells with edema. Both diffuse and focal Infiltration of lymphoid cells with oedema, degeneration, necrosis and desquamation was observed in sections of affected heart, lungs, kidney, trachea and proventriculus of some affected cases. Sections of affected skin showed keratinization and discrete lymphoid aggregation in feather follicles.

The present study suggested that Marek′s Disease is still prevalent in many organized poultry farms. Necropsy examination along with cytological evaluation of tumorous lesions in various organs of suspected neoplastic cases was found to be an aid in diagnosing Marek′s Disease which can give necessary preliminary information in the field condition. Histopathological examination is still found to be one of the inexpensive and reliable methods for diagnosis and differential diagnosis of Marek′s Disease from other neoplastic diseases in poultry.