Serologic and experimental investigations of contagious ecthyma in Alaska

Serologic evidence of contagious ecthyma (CE) was found in domestic sheep (Ovis aries), domestic goats (Capra hircus), Dall sheep (Ovis dalli), and musk-ox (Ovibos moschatus) in Alaska. A moose (Alces alces) calf and a caribou (Rangifer tarandus) fawn were susceptible to experimental infection and both developed antibody titers as a result. CE virus was isolated from lesions of Dall sheep which were involved in a natural outbreak of the disease.     

Serum antibody prevalence of malignant catarrhal fever viruses in seven wildlife species from Alaska

Blood samples were collected from seven species of free-ranging ungulates in Alaska. Sera were tested for evidence of exposure to malignant catarrhal fever viruses (MCFV) by means of a competitive enzyme-linked immunosorbent assay. Antibody prevalences were as follows: muskox (Ovibos moschatus) 100 positive samples of 104 tested (96%); Dall sheep (Ovis dalli) 212 of 222 (95%); elk (Cervus elaphus) 14 of 51 (27%); bison (Bison bison) 34 of 197 (17%); caribou (Rangifer tarandus) nine of 232 (4%); Sitka black-tailed deer (Odocoileus hemionus sitkensis) one of 49 (2%); and moose (Alces alces) three of 219 (1%). Antibody prevalence in a bison population from the Interior was stable over a 5 yr period. These results indicate that at least one virus in the MCF group is enzootic in Dall sheep and muskox in Alaska. Lower antibody prevalences in the other species in this survey suggest that MCFV are latent or subclinical in these free-ranging ruminants. Whole blood samples were collected from 14 Dall sheep and subjected to a polymerase chain reaction assay. Fragments of ovine herpesvirus-2 DNA were detected in six of the samples. The significance of these findings for the health of free-ranging ungulates in Alaska is unknown.     

Rumen Ciliate Fauna of Alaskan Moose (Alces americana), Musk-Ox (Ovibos moschatus) and Dall Mountain Sheep (Ovis dalli)*

Total numbers, generic distribution and percentage species distribution were determined for the ciliate protozoa in rumen contents obtained from Alaskan moose (Alces americana), musk-ox (Ovibos moschatus) and Dall mountain sheep (Ovis dalli). The musk-ox has a fauna somewhat similar to that previously observed in reindeer and caribou. In contrast, only protozoa in the genus Entodinium were observed in moose, while Dall mountain sheep have a fauna unique among Alaskan ruminants studied to date. Other than Entodinium exiguum which was common to all animals, only 2 additional species of Entodinium, observed in the moose and musk-ox, occurred in more than one animal species. Four new species of protozoa are described, Entodinium dalli sp.n., Entodinium constrictum sp.n. and Polyplastron alaskum sp.n. from the Dall mountain sheep and Entodinium alces sp.n. from moose.     

Development and pathogenesis of Parelaphostrongylus odocoilei (nematoda: protostrongylidae) in experimentally infected thinhorn sheep (Ovis dalli )

Recently, the protostrongylid nematode Parelaphostrongylus odocoilei has been reported in a new host species, thinhorn sheep (Ovis dalli). For the first time, we completed the life cycle of P. odocoilei in three Stone's sheep (O. dalli stonei) and two thinhorn hybrids (O. dalli stonei x O. dalli dalli), each infected with 200 third-stage larvae from slugs (Deroceras laeve). The prepatent period ranged from 68 days to 74 days, and shedding of first-stage larvae (L1) peaked at >10,000 L1 per gram of feces between 90 and 110 days postinfection. A total of 75, 27, and 14 adult P. odocoilei were recovered from skeletal muscles of three Stone's sheep. Starting in the prepatent period, all infected sheep lost weight and developed peripheral eosinophilia. At 2 wk before patency, two thinhorn hybrids developed neurologic signs (hind end ataxia, loss of conscious proprioception, and hyperesthesia) that resolved at patency. Eosinophilic pleocytosis and antibody to Parelaphostrongylus spp. were detected in the cerebrospinal fluid of the affected sheep, suggesting that the migration route of the "muscleworm" P. odocoilei may involve the central nervous system. Twenty days after treatment with ivermectin, neurologic signs recurred and larval shedding ceased in one infected thinhorn hybrid, whereas multiple treatments transiently suppressed but did not eliminate larval shedding in the other. During patency, two Stone's sheep with numerous eggs and larvae of P. odocoilei in the lungs died of respiratory failure following anesthesia or exertion. Parelaphostrongylus odocoilei has widespread geographic distribution, high prevalence, the possibility of causing neurologic and respiratory disease, resistance to treatment, and may constitute a significant emerging disease risk for thinhorn sheep.     

The melanocyte-stimulating hormone receptor (MC1-R) gene as a tool in evolutionary studies of artiodactyles

The complete coding region of the melanocyte-stimulating hormone receptor (MC1-R) gene was characterized in species belonging to the two families Bovidae and Cervidae; cattle (Bos taurus), sheep (Ovis aries), goat (Capra hircus), muskox (Ovibos moschatus), roe deer (Capreolus capreolus), reindeer (Rangifer tarandus), moose (Alces alces), red deer (Cervus elaphus) and fallow deer (Dama dama). This well conserved gene is a central regulator of mammalian coat colour. Examination of the interspecies variability revealed a 5.3-6.8% divergence between the Cervidae and Bovidae families, whereas the divergence within the families were 1.0-3.1% and 1.2-4.6%, respectively. Complete identity was found when two subspecies of reindeer, Eurasian tundra reindeer (R.t. tarandus) and Svalbard reindeer (R.t. platvrhynehus), were analyzed. An rooted phylogenetic tree based on Bovidae and Cervidae MC1-R DNA sequences was in complete agreement with current taxonomy, and was supported by bootstrapping analysis. Due to different frequencies of silent vs. replacement mutations, the amino acid based phylogenetic tree contains several dissimilarities when compared to the DNA based phylogenetic tree.     

New ruminant hosts and wider geographic range identified for Babesia odocoilei (Emerson and Wright 1970)

Babesia odocoilei was found to infect two previously unknown host species, desert bighorn sheep (Ovis canadensis nelsoni) and musk oxen (Ovibos moschatus), both of which are members of the family Bovidae. Previously, B. odocoilei has been reported in only Cervidae hosts. New geographic regions where B. odocoilei infections have not been reported previously include Pennsylvania and New York, where fatal babesiosis has occurred in reindeer (Rangifer tarandus tarandus); New Hampshire, where elk (Cervus elaphus canadensis) have been affected; and California, home of the infected desert bighorn sheep. Infection with B. odocoilei in these hosts was confirmed by parasite small subunit ribosomal RNA gene sequence analysis. A serosurvey for B. odocoilei antibody activity in New Hampshire showed prevalence rates of 100% at two elk farms and 12% at another farm. Control of potential vector ticks, Ixodes scapularis, especially when translocating livestock, is imperative to prevent outbreaks of babesiosis in managed herds of potential host species.     

New host and geographic records for two protostrongylids in Dall's sheep.

Biodiversity survey and inventory have resulted in new information on the distribution of Protostrongylidae in Dall's sheep (Ovis dalli dalli) from the Northwest Territories (NT, Canada) and from Alaska (AK, USA). In 1998, Parelaphostrongylus odocoilei adults were found for the first time in the skeletal muscles of Dall's sheep in the Mackenzie Mountains (NT). Adult P. odocoilei were associated with petechial and ecchymotic hemorrhages and localized myositis; eggs and larvae in the lungs were associated with diffuse granulomatous pneumonia. Experimental infections of the slugs Deroceras laeve and Deroceras reticulatum with dorsal-spined first-stage larvae assumed to be P. odocoilei, from ground-collected feces from Dall's sheep in the Mackenzie Mountains, yielded third-stage larvae by at least 28 (in D. laeve) and 48 (in D. reticulatum) days post-infection. Third-stage larvae emerged from D. laeve between days 19 and 46 post-infection and emergence occurred both at room temperature and at 10 to 12 C. Protostrongylus stilesi were definitively identified from the lungs of Dall's sheep collected in the Mackenzie Mountains, NT in 1998. Specimens collected from sheep in the Mackenzie Mountains, NT in 1971-72, and the Alaska Range, AK in 1972 were also confirmed as P. stilesi. Lung pathology associated with adults, eggs, and larvae of P. stilesi was similar to that described in bighorn sheep (Ovis canadensis). Concurrent infections with P. odocoilei and P. stilesi in a single host have not been previously reported.     

Evidence of three new members of malignant catarrhal fever virus group in muskox (Ovibos moschatus), Nubian ibex (Capra nubiana), and gemsbok (Oryx gazella)

Six members of the malignant catarrhal fever (MCF) virus group of ruminant rhadinoviruses have been identified to date. Four of these viruses are clearly associated with clinical disease: alcelaphine herpesvirus 1 (AlHV-1) carried by wildebeest (Connochaetes spp.); ovine herpesvirus 2 (OvHV-2), ubiquitous in domestic sheep; caprine herpesvirus 2 (CpHV-2), endemic in domestic goats; and the virus of unknown origin found causing classic MCF in white-tailed deer (Odocoileus virginianus; MCFV-WTD). Using serology and polymerase chain reaction with (degenerate primers targeting a portion of the herpesviral DNA polymerase gene, evidence of three previously unrecognized rhadinoviruses in the MCF virus group was found in muskox (Ovibos moschatus), Nubian ibex (Capra nubiana), and gemsbok (South African oryx, Oryx gazella), respectively. Base on sequence alignment, the viral sequence in the muskox is most closely related to MCFV-WTD (81.5% sequence identity) and that in the Nubian ibex is closest to CpHV-2 (89.3% identity). The viral sequence in the gemsbok is most closely related to AlHV-1 (85.1% identity). No evidence of disease association with these viruses has been found.     

Protostrongylid parasites and pneumonia in captive and wild thinhorn sheep (Ovis dalli)

We describe health significance of protostrongylid parasites (Parelaphostrongylus odocoilei and Protostrongylus stilesi) and other respiratory pathogens in more than 50 naturally infected Dall's sheep (Ovis dalli dalli) from the Mackenzie Mountains, Northwest Territories (1998-2002) as well as in three Stone's sheep (O. d. stonei) experimentally infected with P. odocoilei (2000-2002). Histological lesions in the brain and distribution of P. odocoilei in the muscles of experimentally and naturally infected sheep were consistent with a previously hypothesized "central nervous system to muscle" pattern of migration for P. odocoilei. Dimensions of granulomas associated with eggs of P. odocoilei and density of protostrongylid eggs and larvae in the cranial lung correlated with intensity of larvae in feces, and all varied with season of collection. Prevalence of P. stilesi based on the presence of larvae in feces underestimated true prevalence (based on examination of lungs) in wild Dall's sheep collected in summer and fall. Similarly, counts of both types of protostrongylid larvae in feces were unreliable indicators of parasitic infection in wild Dall's sheep with concomitant bacterial pneumonia associated with Arcanobacterium pyogenes, Pasteurella sp., and Mannheimia sp. Diffuse, interstitial pneumonia due to P. odocoilei led to fatal pulmonary hemorrhage and edema after exertion in one experimentally infected Stone's sheep and one naturally infected Dall's sheep. Bacterial and verminous pneumonia associated with pathogens endemic in wild Dall's sheep in the Mackenzie Mountains caused sporadic mortalities. There was no evidence of respiratory viruses or bacterial strains associated with domestic ruminants, from which this population of wild sheep has been historically isolated.     

Yersiniosis in free-ranging muskoxen on Banks Island, Northwest Territories, Canada.

Sixty-seven muskox (Ovibos moschatus) carcasses, 53 skeletal remains and two sick muskoxen were seen during an aerial survey of the Thomsen River region, northern Banks Island, Northwest Territories, Canada in late July 1986. Complete necropsies were performed on 29 muskoxen estimated to have died within the previous 3 to 5 days. Twenty were diagnosed with acute yersiniosis due to Yersinia pseudotuberculosis serotype 1B and were in excellent body condition. A diagnosis could not be made on seven animals due to marked autolysis; however, these muskoxen also were in excellent body condition. The remaining two were aged, emaciated muskoxen. This report describes the first occurrence of yersiniosis in free-ranging muskoxen and the first documentation of large scale mortality due to this disease in a free-ranging population of wild ungulates.     

Geographic distribution of the muscle-dwelling nematode Parelaphostrongylus odocoilei in North America, using molecular identification of first-stage larvae

Molecular identification of dorsal-spined larvae (DSL) from fecal samples indicates that the protostrongylid parasite Parelaphostrongylus odocoilei occupies a broader geographic range in western North America than has been previously reported. We analyzed 2,124 fecal samples at 29 locations from thinhorn sheep (Ovis dalli dalli and O. d. stonei), bighorn sheep (Ovis canadensis canadensis and O. c. californiana), mountain goats (Oreamnos americanus), woodland caribou (Rangifer tarandus caribou), mule deer (Odocoileus hemionus hemionus), and black-tailed deer (O. h. columbianus). The DSL were recovered from populations of thinhorn sheep south, but not north, of the Arctic Circle, and they were not recovered from any of the bighorn sheep populations that we examined. In total, DSL were recovered from 20 locations in the United States and Canada (Alaska, Yukon Territory, Northwest Territories, British Columbia, Alberta, and California). The DSL were identified as P. odocoilei by comparing sequences of the second internal transcribed spacer (ITS2) region of ribosomal RNA among 9 protostrongylid species validated by adult comparative morphology. The ITS2 sequences were markedly different between Parelaphostrongylus and other protostrongylid genera. Smaller fixed differences served as diagnostic markers for the 3 species of Parelaphostrongylus. The ITS2 sequences (n = 60) of P. odocoilei were strongly conserved across its broad geographic range from California to Alaska. Polymorphism at 5 nucleotide positions was consistent with multiple copies of the ITS2 within individual specimens of P. odocoilei. This work combines extensive fecal surveys, comparative morphology, and molecular diagnostic techniques to describe comprehensively the host associations and geographic distribution of a parasitic helminth.     

Experimental transmission of gastro-intestinal nematodes between sheep (Ovis aries) and Thomson's gazelles (Gazella thomsonii).

Experimental cross-transmission of gastro-intestinal nematodes between Merino sheep (Ovis aries) and Thomson's gazelles (Gazella thomsonii) from similar but separate grazing habitats in Kenya was studied. Cross-transmission did occur with some species but the faecal egg counts of sheep were higher than the gazelles' following infection with larvae isolated from either sheep or gazelles. Of the 11 gastro-intestinal nematodes which became established in gazelles following infection with larvae cultured from nematodes in gazelles, only Haemonchus contortus, Trichostrongylus probolurus and Cooperia hungi were infective for sheep. Following infection with larvae of either sheep or gazelle origin, the H. contortus recovered from the sheep at necropsy were more numerous and had greater average weights, lengths and spicule lengths than those recovered from the gazelles. This would suggest that H. contortus is primarily a sheep parasite. It is concluded that Thomson's gazelles probably would not contribute significantly to the problem of haemonchosis in sheep in areas of shared grazing, unless efforts were being made to eradicate the parasite from sheep, in which case the gazelles would act as a continuing reservoir of infection.     

Phylogenetic analysis of snow sheep (Ovis nivicola) and closely related taxa

Based on mitochondrial cytochrome b gene sequence analysis, the history of true sheep (Ovis) began approximately 3.12 million years ago (MYA). The evolution of Ovis resulted in three generally accepted genetic groups: Argaliforms, Moufloniforms, and Pachyceriforms. The Pachyceriforms of the subgenus Pachyceros comprise the thin-horn sheep Ovis nivicola (snow sheep), Ovis dalli (Dall and Stone sheep), and Ovis canadensis (Rocky Mountain and desert bighorn). North America wild sheep (O. canadensis and O. dalli) evolved separately from Eurasian wild sheep and diverged from each other about 1.41 MYA. Ancestral stock that gave rise to snow sheep, Moufloniforms, and Argaliforms occurred 2.3 MYA, which then gave rise to two different extant lines of snow sheep that diverged from each other about 1.96 MYA. The more recent nivicola line is genetically closer to the North American wild sheep and may represent a close association during the refugium when Alaska and Siberia were connected by the Bering land bridge. The earlier period of evolution of the Pachyceriforms suggests they may have first evolved in Eurasia, the oldest ancestor then giving rise to North American wild sheep, and that a canadensis-like ancestor most likely gave rise to nivicola. Cytogenetic analysis further validates that the standard diploid number for modern nivicola is 52.     

秦岭羚牛高度重复序列DNA片段的分子克隆和序列分析

羚牛(Budorcas taxicolor)属偶蹄目(Artiodactyla)、牛科(Bovidae),为我国一类大型珍贵保护动物。我们从其基因组中克隆得到若干约800bp的BamHI高度重复序列并对部分克隆进行了序列测定,发现它们显示了很高的同源性。利用其中一个单元为探针,对限制酶消化后的羚牛基因组DNA作杂交分析,发现其杂交谱带不具有个体及亚种间特异性,说明该重复序列在羚牛基因组中具有保守的分布和排列。在牛科动物中,羚牛BamHI片段与绵羊属和山羊属的相关序列具有高度同源性,而与水牛和家牛序列差异较大。这些结果为羚牛与羊亚科物种亲源关系较近的分类学观点提供了分子生物学证据。有证据表明,这些片段可能代表羚牛染色体着丝点的卫星DNA单体。     

Failure to maintain interspecific pregnancy after transfer of Dall's sheep embryos to domestic ewes

Over a 3-year period, 32 Dall's sheep (Ovis dalli dalli) embryos were transferred into 24 domestic sheep (O. aries) recipients and 4 were transferred into 2 Dall's sheep recipients. In the first year, none of the 10 O. aries recipients was diagnosed pregnant. In the following 2 years, 9 (37%) of the domestic sheep recipients were pregnant on Day 18, 8 (33%) on Day 40, 6 (25%) on Day 90 and 4 (16%) on Day 120; 1 aborted at Day 125 and another at Day 145. Pregnancies were established only in ewes that had previously been recipients of Dall's sheep embryos. The 2 remaining pregnant sheep were treated with progesterone from Day 125 until the fetuses were determined to be dead at Day 145. Both of the Dall's sheep recipients (Year 2) established pregnancies; 1 live Dall's sheep lamb was born 174 days after mating. No differences in serum progesterone, oestrone, prostaglandin F-2 alpha metabolites or cortisol concentrations could be detected during pregnancy between recipients carrying Dall's sheep embryos, recipients receiving progesterone treatment or domestic ewes carrying domestic sheep pregnancies. Six fetuses were necropsied (1 at Day 125 and 5 at Day 145-146): all fetuses were premature and had various degrees of hydranencephaly. No significant differences were found when cotyledon numbers were compared among domestic ewes carrying Dall's sheep lambs. Dall's sheep ewes lambing naturally and domestic ewes lambing naturally. These results demonstrate that the transfer of Dall's sheep embryos to domestic ewes results in the establishment but subsequent loss of pregnancy and that these losses occur throughout gestation.     

Diet selection by vertebrate herbivores in the high arctic of Greenland

Microhistological analysis of fecal droppings indicates that graminoids (sedges, grasses, and rushes) and the only willow present, Salix arctica , are primary food items of the muskox Ovibos moschatus , arctic hare Lepus arcticus , and collared lemming Dicrostonyx groenlandicus in northern Greenland (79°-83°N). Plant biomass available during the peak growing season varied with vegetation types from < 2 g m⁻² in polar barrens to 34 g m⁻² in sedge fens. The clustered distribution of vegetation minimizes competition among vertebrate herbivores.     

Nematode related spinal myelomeningitis and posterior ataxia in muskoxen (Ovibos moschatus)

In the fall of 1988 all five animals in a herd of muskoxen (Ovibos moschatus) developed clinical signs of posterior ataxia. Postmortem investigation revealed inflammatory lesions of the caudal part of the spinal cord, mainly as leptomeningitis. Nematodes were seen in close association with the lesions. Although not identified, the parasites were probably an Elaphostrongylus sp.     

An epizootic of Mycoplasma ovipneumoniae infection in captive Dall's sheep (Ovis dalli dalli)

In late spring of 1986, 10 of 23 Dall's sheep (Ovis dalli dalli) at the Metropolitan Toronto Zoo were moved to a new exhibit, where all developed severe respiratory signs refractory to anthelmintic and antibiotic therapy. In July, two animals died with chronic active bronch-pneumonia, and a third was euthanized because of pneumonia several months later. Bacteria were not isolated from the lungs of the first, steptococci and Pasteurella hemolytica were isolated from the other two, respectively; Mycoplasma ovipneumoniae was isolated from both. Pulmonary lesions in all three sheep were consistent with Mycoplasma sp. infection. Nasal swabs of the remaining animals yielded no consistent bacterial isolates; however, four of eight sheep were positive for M. ovipneumoniae. Viral cultures yielded an as yet unidentified herpesvirus. Sheep in the original and new herds had no serologic titers to parainfluenza-3, equine viral rhinopneumonitis, or infectious bovine rhinotracheitis, and had variable titers against bovine respiratory syncytial virus. No titers against M. ovipneumoniae were present in 13 sheep still in the original exhibit, but titers varied from 1:32 to 1:256 in eight pneumonic sheep. Sera taken from three sheep before or early in the outbreak were all negative for antibody to M. ovipneumoniae. Two of the affected Dall's sheep had been in contact with domestic sheep in the winter of 1985-1986, and M. ovipneumoniae was subsequently cultured from the domestic flock. Exposure to a new pathogen, and environmental and social stress in a new exhibit may have resulted in this severe disease in Dall's sheep.     

Lumpy jaw in wild sheep and its evolutionary implications

The distribution and prevalence of mandibular osteomyelitis, lumpy jaw, and other dental anomalies in wild sheep were investigated and their biological and evolutionary implications were assessed. Our survey was based on 3,363 mandibles of wild sheep and 1,028 from domesticated varieties. Lumpy jaw is widespread in wild sheep of North America, but it is rare or absent in wild sheep from Eurasia. Among the subspecies of Ovis spp. in North American, the thinhorn sheep (Ovis dalli) were the most seriously impacted, with a prevalence in Dall's sheep (O. dalli dalli) of 23.3% and 29.3% in Stone's sheep (O. dalli stonei). Among the bighorns (O. canadensis), the Rocky Mountain subspecies (O. canadensis canadensis) had a higher rate (12.1%) than other subspecies. Lumpy jaw was not documented in the desert sheep of Baja California (O. canadensis cremnobates, O. canadensis weemsii). Based on data from affected thinhorn sheep, it appears there is an inverse relationship between age of a subspecies in a long term evolutionary context and susceptibility to lumpy jaw. In Eurasian wild sheep lumpy jaw is rare or absent with prevalences ranging from 0 to 7.1% among suspecies, and in domesticated breeds the prevalence averaged 5.0%. The impact of lumpy jaw on different age classes or longevity is equivocal, although females are more susceptible than males. Lumpy jaw appears to effect horn development in males.     

Experimental infection of some North American wild ruminants and domestic sheep with Mycobacterium paratuberculosis: clinical and bacteriological findings

Mycobacterium paratuberculosis originally isolated from bighorn sheep (Ovis canadensis) with spontaneous paratuberculosis was used to orally inoculate Rocky Mountain elk (Cervus elaphus nelsoni) calves, mule deer (Odocoileus hemionus) fawns, white-tailed deer (Odocoileus virginianus) fawns, bighorn X mouflon (Ovis musimon) hybrid lambs, and domestic lambs. All experimentally exposed animals became infected. During the first year of infection, hybrid and domestic sheep were able to control the infection but infection was progressive in elk and deer. Clinical paratuberculosis occurred only in mule deer.