A nine - year retrospective study of avian neoplastic diseases in Zaria, Kaduna state, Nigeria
Avian neoplastic diseases have been identified as one of the leading causes of mortality and production losses in commercial chickens in Nigeria. Although available reports described the trend of Marek’s disease in Zaria, Kaduna state, they did not take cognizance of other neoplastic diseases of poultry hence the need for this study. The clinic records of the Avian Clinic of the Veterinary Teaching Hospital (VTH), Ahmadu Bello University (ABU), Zaria, were examined for cases of all avian neoplastic diseases from 2002 to 2010. The overall prevalence of avian neoplastic diseases was 7.58% (234/3085). Marek’s disease (MD) and avian leukosis (AL) were the only avian neoplastic diseases of poultry reported during the period under review. Marek’s disease contributed 85.90% (201/234) of the total avian neoplastic diseases outbreaks while AL was responsible for only 14.10% (33/234) of the outbreaks. The overall prevalence of MD was 6.25% (201/3085) while that of AL was 1.07% (33/3085). Chicken (99.57%) and duck (0.43%) were the only species of birds affected by the diseases. The types of chickens that were affected include commercial layers (97.85%), exotic broilers (0.86%), exotic cockerels (0.86%) and Nigerian indigenous chicken (0.43%). The average age of poultry affected was 20.17 (SD=±2.6) weeks for MD and 41.43 (SD=±15.4) weeks for AL. Weight loss (55.98%), ruffled feathers (47.01%), diarrhea (39.79%) and leg paralysis (17.52%) were the most reported clinical signs. The most consistent gross lesions observed were hepatomegaly (76.50%), emaciated carcass (75.64%), renomegaly (52.56%) and splenomegaly (44.87%). Neoplastic growths were mostly observed on the liver (46.58%), kidney (28.2%) and heart (25.21%). The sciatic nerve (20.51%) and bursa of Fabricius (3.85%) were also affected. There is a remarkable increase in the cases of avian neoplastic diseases over the study period which underscores the importance of a National control program for these important diseases of poultry.
Keywords: Avian neoplastic diseases, Avian leukosis, Clinico-pathological changes, Marek’s disease, Prevalence