Infectious laryngotracheitis virus in commercial hens: a serological study based on enzyme-linked immunosorbent assay.

Serum samples collected from 23 flocks of commercial hens from three different companies were tested by enzyme-linked immunosorbent assay (ELISA) for antibodies against infectious laryngotracheitis (ILT) virus, and data were analyzed statistically. Geometric mean titers (GMTs) were compared from hens that were unvaccinated, once-vaccinated, or twice-vaccinated, from single-age farms or multiple-age farms, from molted or unmolted flocks, and from different companies. There were significant differences among the groups compared by vaccination, between the single-age and multiple-age groups, and between the molted and unmolted groups. The GMT of unvaccinated flocks and the GMT of molted flocks that had been vaccinated once as pullets with a chick-tissue-culture-origin (CTCO) live vaccine could not be differentiated. The ELISA is useful to detect and quantitate ILT vaccine-induced antibody, but it does not reliably identify older flocks that were vaccinated at a young age with CTCO vaccine.

Toxicosis in broiler chicks due to excess dietary ethoxyquin.

A commercial broiler company experienced a sudden increase of mortality in four flocks at two separate locations. Affected houses had red dust on inside walls and on the equipment. Affected chickens were 10 to 18 days old. Grossly, chickens had pale, swollen kidneys, dark-brown enlarged livers, and urates in joint spaces. Histologically, the kidneys had multifocal proximal tubular necrosis, the livers had dilated sinusoids, biliary hyperplasia, and accumulation of brown pigment in hepatocytes and bile ducts. One starter ration was analyzed, and it contained 6500 mg ethoxyquin/kg. The red dust in the houses and the brown pigment in livers were interpreted to be ethoxyquin. Clinical signs and histologic lesions were reproduced experimentally with 12,500 mg ethoxyquin/kg feed.