Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Necrotizing and haemorrhagic hepatitis and enteritis in commercial layer pullets.

This case report describes an episode of recurring severe necrotizing and haemorrhagic hepatitis and enteritis experienced in a flock of commercial layer pullets at 12 weeks of age and again at 18 weeks of age in Indiana. Pullets had been vaccinated at 10 weeks old using a trivalent Salmonella Enteritidis (SE)/Newcastle disease/infectious bronchitis oil-emulsion-inactivated vaccine. The pullets were found dead at 12 weeks with firm but friable, enlarged, haemorrhagic livers, enlarged spleens, and necrohaemorrhagic intestines.

Outbreak of Type C Botulism in Commercial Layer Chickens.

This report describes an outbreak of type C botulism in two organic, free-range commercial layer farms in the Midwest. Hens affected were 64-wk-old Hy-Line brown hens and 34-wk-old Hy-Line brown hens owned by the same company, but housed on different premises, with approximately 20,000 birds per house. Mortality over the 2 wk of investigation was estimated to be up to 8% and 2.

Role of Marek's disease herpesvirus in the induction of tumours in Japanese quail (Coturnix coturnix japonica) by methylcholanthrene.

The QT35 cell line, established from 20-methylcholanthrene (MCA)-induced tumours in Japanese quail, is positive for Marek's disease virus (MDV), and therefore we examined whether MDV is important for the development of MCA-induced tumours. Japanese quail were inoculated with the JM16 strain of MDV at 1 or 3 days of age or left uninoculated. At 3 weeks of age, quail were injected in the breast muscle with 4 mg MCA in corn oil or corn oil alone.

Pathogenicity of a quail (Coturnix coturnix japonica)-derived Marek's disease virus rescued from the QT35 cell line.

The QT35 cell line was established in 1977 from methylcholanthrene-induced tumors in Japanese quail. It was later shown that at least some of the QT35 cell lines were latently infected with Marek's disease (MD) virus (MDV). An MDV-like herpesvirus, named quail MDV (QMDV), was isolated from QT35 cells in 2000 by Yamaguchi et al.

BG1 has a major role in MHC-linked resistance to malignant lymphoma in the chicken.

Pathogen selection is postulated to drive MHC allelic diversity at loci for antigen presentation. However, readily apparent MHC infectious disease associations are rare in most species. The strong link between MHC-B haplotype and the occurrence of virally induced tumors in the chicken provides a means for defining the relationship between pathogen selection and MHC polymorphism.

Amelia/ectromelia in association with scoliosis in three commercial layer hens (Gallus gallus forma domestica).

Three wingless "healthy" pullet hens were serendipitously discovered at a grow-out facility for an egg-production ranch. Two of the birds were amelic and one was ectromelic. The defect in these chickens differs from the previously reported wingless mutations in that all three affected birds also had scoliosis.

Seroprevalence of antibodies specific for gram-negative core antigens in chickens on the basis of an Escherichia coli J5 enzyme-linked immunosorbent assay.

Antibodies directed toward gram-negative core antigens (GNCAs) have been demonstrated in many mammalian species but to date are unexamined in any avian species. An enzyme-linked immunosorbent assay with phenol-killed whole cell Escherichia coli J5 was used to assess the presence of serum antibodies directed toward GNCAs in chickens. The first experiment consisted of collecting blood samples from randomly selected hens at egg laying ranches in northern California.

Effect of in ovo vaccine delivery route on herpesvirus of turkeys/SB-1 efficacy and viremia.

A study was designed to ascertain the influence of in ovo site of inoculation and embryonic fluid type on the development of Marek's disease (MD) vaccine viremia and efficacy against MD challenge. The experiments were divided into in vitro and in vivo phases. In the in vitro phase, herpesvirus of turkeys/SB-1 vaccine was combined with basal medium eagle (BME) medium (control), amniotic fluid, or allantoic fluid and subsequently titrated on secondary chick embryo fibroblast cultures.