Histopathology in diagnosis of broiler chicken and layer diseases--review of cases 1999-2010.

The aim of this study was to estimate the prevalence of histopathological lesions in the different organs in relation to the commercial-type and the age of birds (i.e. broiler chickens and layers). During the period 1999-2010 a total of 189 cases was submitted to the Division of Animal Pathomorphology, Department of Pathology and Veterinary Diagnostics at WULS. Most cases were found in broiler chickens (66.7%). The majority of the histopathological lesions were detected in the liver and lymphoid organs. In of 29% cases of hepatic injury pathognomonic lesions associated with inclusion body hepatitis (IBH) were found. The mean age of birds was 23 days. Among IBH cases proventriculitis (58%) was more often found than gizzard lesions (25.8%). Interestingly, we noted some intranuclear inclusions in the epithelial cells within the proventriculus. A low percentage of histopathological evidence of infectious bursal disease (IBD) was reported in chickens. The gastrointestinal tract was the second most frequent predilection site for histopathological lesions. Histopathological findings within the heart and lungs were less common and were more often seen in the upper respiratory tract. Cases of infectious laryngotracheitis (ILT) were registered in broiler chickens (3.2%, mean age 37 days) and in layers (4.8%; mean age 196 days). Lesions associated with Marek's disease, avian leukosis and fowl pox were recognized only in layers, respectively in 3.2% (mean age 176 days), 1.6% (mean age 205 days) and 1.1% (mean age 196 days) of all cases. Avian encephalomyelitis (AE) was noted only in 0.5% of all cases.