Ivan Dinev

The purpose of investigations was to determine, by means of pathomorphological methods, the incidence of different rickets forms and their role for the occurrence of other illnesses in broiler chickens in Bulgaria.Clinical, blood biochemical, gross anatomy and histological investigations were carried out in broiler chickens with signs of rickets. The studies were performed in 12 broiler flocks in 4 farms located in different regions of the country. Based on macro- and microscopic lesions, alterations specific for hypocalcaemic rickets were observed in two farms, whereas signs of hypophosphataemic rickets – in the other two. The rickets diagnosis was confirmed by analysis of blood serum calcium, magnesium and inorganic phosphate concentrations.At the age of 30–35 days, various pathological states were observed in the same farms. The presented results suggested that existing problems in studied flocks were associated with an earlier occurrence of rickets.

The purpose of investigations was to determine, by means of pathomorphological methods, the incidence of different rickets forms and their role for the occurrence of other illnesses in broiler chickens in Bulgaria. Clinical, blood biochemical, gross anatomy and histological investigations were carried out in broiler chickens with signs of rickets. The studies were performed in 12 broiler flocks in 4 farms located in different regions of the country. Based on macro- and microscopic lesions, alterations specific for hypocalcaemic rickets were observed in two farms, whereas signs of hypophosphataemic rickets - in the other two. The rickets diagnosis was confirmed by analysis of blood serum calcium, magnesium and inorganic phosphate concentrations. At the age of 30-35 days, various pathological states were observed in the same farms. The presented results suggested that existing problems in studied flocks were associated with an earlier occurrence of rickets.

This paper reports an enzootic outbreak and spontaneous regression of keratoacanthomas among adult layer hens with lesions on the skin of the legs. The observations were performed in a flock of 55,000 commercial layers (50,000 Lohmann White and 5,000 Lohmann Brown). At the age of 30 weeks, Lohmann White layers exhibited a number of growths (at an average of 60 hens per week, representing 0.1% of the flock) in the region of leg toes on a daily basis over 28 weeks that regressed during the remaining flock production period. Gross and histological investigations identified the lesions as keratoacanthomas. PCR analysis was negative for avian leukosis virus (ALV) and reticuloendotheliosis virus (REV). The present investigations have revealed an unusual case: this is the first report on an enzootic outbreak of multiple keratoacanthomas in commercial layers. The results of the aetiological investigations do not show a relation to any infectious agent or a chemical-toxic cause. The abnormal invasion of keratinocytes from the stratum corneum leading to neoplasms in this case coincides with the phase of peak laying capacity which is in fact a stress factor and might be regarded as a provocative moment.