Six Rocky Mountain bighorn sheep were raised in captivity from birth (n = 5) or taken from the wild as a lamb (n = 1). After the bighorn sheep were in captivity for over a year, 6 clinically normal domestic sheep were placed on the 2 ha of pasture on which the bighorn sheep were kept. Nasal swab specimens were obtained from all sheep at the time the domestic sheep were introduced. Pasteurella haemolytica was isolated from swab specimens obtained from 4 of 6 domestic sheep, but not from specimens obtained from the bighorn sheep. All 6 bighorn sheep died of acute hemorrhagic pneumonia after exposure to domestic sheep. Death in the bighorn sheep occurred on days 4, 27, 27, 29, 36, or 71 after initial exposure to domestic sheep. Pasteurella haemolytica was isolated from respiratory tract tissue specimens of all bighorn sheep at the time of death. None of the domestic sheep were clinically ill during the study. At the end of the study, 3 of 6 domestic sheep were euthanatized, and at necropsy, P haemolytica was isolated from 2 of them. The most common serotypes in bighorn and domestic sheep were P haemolytica T-3 and A-2. Other serotypes isolated included P haemolytica A-1, A-9, and A-11 in bighorn sheep and A-1 in domestic sheep. On the basis of results of this study and of other reports, domestic sheep and bighorn sheep should not be managed in proximity to each other because of the potential fatal consequences in bighorn sheep.

The amphotropic murine leukemia virus (MLV) has been shown to infect mammalian species other than mice. If this virus infects and expresses genes in cells of livestock species (cattle, sheep, and pigs) it has potential for use as a vector to produce transgenic livestock. Because the gene-injection technique for producing transgenic animals is inherently inefficient, our laboratory was interested in identifying or constructing retroviral vectors capable of infecting livestock embryos. The infectivity of an amphotropic MLV-based vector for ovine, bovine, and porcine cells was tested. Experiments were also conducted to test the ability of the amphotropic MLV promoter, compared with known strong promoters, to express genes in cells from these species. Results indicated that amphotropic MLV infects and expresses genes efficiently in porcine cells and is, therefore, a potential vector for producing transgenic pigs. Infection was not detected in cells from adult bovine and ovine species; however, low levels of infection, with subsequent gene expression, were detected in cells derived from bovine embryos.

Efficacy of oral administration of 20 mg of triclaben-dazole/kg of body weight was evaluated against 12-week Fascioloides magna infections in 12 sheep, each inoculated orally with 250 viable metacercariae. From 6 sheep treated with triclabendazole, 1 immature F magna was recovered, whereas 116 F magna with a mean length of 19 +/- 6.5 mm were recovered from 6 untreated control sheep. Efficacy of triclabendazole was 99.14%. Signs of toxicosis or illness were not observed in the sheep.