Patho-epidemiological studies on peripheral neuropathy in replacement pullets

The present research work was conducted to study the pathological and epidemiological features related to peripheral neuropathy (PN) in the field cases from ten replacement pullet flocks of different layer poultry farms in and around Anand District of Gujarat.The affected birds exhibited signs of paresis and lameness at an age of eight to nine weeks which lasted for a period of six to seven weeks more.The overall lameness was recorded to be 5.44% which ranged from 4.11 to 9.77% between different farms. All the ten flocks studied for PN were vaccinated against MD with bivalent vaccine HVT + SB1, both at the hatchery and farm level.The clinical signs observed in the birds affected by PN were characterized by various degree of lameness, paralysis and occasionally incoordination and ataxia.The typical ‘spay leg’ posture was noticed in many birds showing paralytic effects. Gross pathological lesions consisted of enlargement of sciatic plexus and sciatic nerves in all the birds. Enlargement of dorsal root ganglia and brachial plexus were also noted in many birds. Enlarged nerves showed swelling, edema, loss of striation and discoloration. Histopathological examination revealed focal accumulation of inflammatory cells at the entrance of the nerve roots in the spinal cord. In the brachial plexus also similar inflammatory cell infiltration was observed. Sciatic plexus and sciatic nerves showed the most prominent and main diagnostic lesions of concurrent inflammation and demyelination. The PCR to detect serotype-1 MDV from the feather follicles of all the affected birds yielded negative results.