Ovis Canadensis

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Walter M. Boyce - One of the best experts on this subject based on the ideXlab platform.

  • Phylogeographic and population genetic structure of bighorn sheep (Ovis Canadensis) in North American deserts
    Journal of mammalogy, 2016
    Co-Authors: Michael R. Buchalski, Daphne A. Gille, Maria Cecilia T. Penedo, Benjamin N. Sacks, Holly B. Ernest, Scott A. Morrison, Walter M. Boyce
    Abstract:

    Fossil data are ambiguous regarding the evolutionary origin of contemporary desert bighorn sheep ( Ovis Canadensis subspecies). To address this uncertainty, we conducted phylogeographic and population genetic analyses on bighorn sheep subspecies found in southwestern North America. We analyzed 515 base pairs of mtDNA control region sequence and 39 microsatellites in 804 individuals from 58 locations. Phylogenetic analyses revealed 2 highly divergent clades concordant with Sierra Nevada ( O. c. sierrae ) and Rocky Mountain ( O. c. Canadensis ) bighorn and showed that these 2 subspecies both diverged from desert bighorn prior to or during the Illinoian glaciation (~315-94 thousand years ago [kya]). Desert bighorn comprised several more recently diverged haplogroups concordant with the putative Nelson ( O. c. nelsoni ), Mexican ( O. c. mexicana ), and Peninsular ( O. c. cremnobates ) subspecies. Corresponding estimates of effective splitting times (~17-3 kya), and haplogroup ages (~85-72 kya) placed the most likely timeframe for divergence among desert bighorn subspecies somewhere within the last glacial maximum. Median-joining haplotype network and Bayesian skyline analyses both indicated that desert bighorn collectively comprised a historically large and haplotype-diverse population, which subsequently lost much of its diversity through demographic decline. Using microsatellite data, discriminant analysis of principle components (DAPC) and Bayesian clustering analyses both indicated genetic structure concordant with the geographic distribution of 3 desert subspecies. Likewise, microsatellite and mitochondrial-based FST comparisons revealed significant fixation indices among the desert bighorn genetic clusters. We conclude these desert subspecies represent ancient lineages likely descended from separate Pleistocene refugial populations and should therefore be managed as distinct taxa to preserve maximal biodiversity. Los datos de fosiles sobre el origen evolutivo de las ovejas del desierto ( Ovis Canadensis subespecies) contemporaneas son ambiguos. Para dilucidar esta incertidumbre, llevamos a cabo analisis filogeograficos y de genetica de poblaciones entre cinco subespecies de ovejas del suroccidente de Norteamerica. Analizamos 515 pb de secuencia de la region control del ADN mitocondrial y 39 microsatelites en 804 ovejas de 58 localidades. Los analisis filogeneticos revelaron 2 clados altamente divergentes concordantes con ovejas de la Sierra Nevada ( O. c. sierrae ) y de las Montanas Rocosas ( O. c. Canadensis ), y demostraron que estas dos subespecies divergieron antes o durante la glaciacion de Illinois (315,000-94,000 anos). Las ovejas del desierto formaron varios haplogrupos recientemente derivados concordantes con las subespecies de Nelson ( O. c. nelsoni ), Mexico ( O. c. mexicana ) y peninsular ( O. c. cremnobates ). Las estimaciones correspondientes al tiempo de separacion efectiva (17,000-3,000 anos) y edades de haplogrupos (85,000-72,000 anos) son los plazos mas probables para las divergencias entre subespecies de ovejas del desierto dentro de la ultima glaciacion maxima. Analisis de redes de haplotipos de union de medias y analisis bayesianos de lineas de horizonte indicaron que las ovejas del desierto formaron una poblacion historicamente grande y diversa en terminos de haplotipos, que luego perdieron gran parte de su diversidad a traves de un descenso demografico. Utilizando datos de microsatelites los analisis DAPC y TESS indicaron agrupamiento genetico concordante con la distribucion geografica actual de las tres subespecies. Asimismo, comparaciones de FST con datos de microsatelites y mitocondriales revelaron indices de fijacion significativos entre los grupos geneticos de ovejas del desierto. Concluimos que estas subespecies de ovejas del desierto representan linajes antiguos que probablemente descienden de poblaciones de distintos refugios del Pleistoceno, y que por lo tanto deben ser manejadas como taxones distintos para preservar su biodiversidad maxima.

  • Genetic population structure of Peninsular bighorn sheep (Ovis Canadensis nelsoni) indicates substantial gene flow across US-Mexico border
    Biological Conservation, 2015
    Co-Authors: Michael R. Buchalski, Walter M. Boyce, Asako Y. Navarro, T. Winston Vickers, Mathias W. Tobler, Lisa A. Nordstrom, Jorge Alaníz García, Daphne A. Gille, Maria Cecilia T. Penedo, Oliver A. Ryder
    Abstract:

    Abstract Within the United States (US), Peninsular bighorn sheep (Ovis Canadensis nelsoni, PBS) are listed as federally endangered. Despite known metapopulation structure, little is known regarding functional connectivity across the international border with Mexico. Increasing threats to connectivity associated with highway expansion, renewable energy development, and completion of the US–Mexico border fence, led us to conduct a study of genetic variation and spatial structure. Blood and fecal samples were collected (n = 224) on both sides of the border from 1992 to 2013. Genetic data was obtained for 25 microsatellite loci and 515 base pairs of the mitochondrial DNA control region. Microsatellite diversity (observed heterozygosity = 0.56; allelic richness = 4.1; inbreeding coefficient = 0.01) was substantial despite past demographic declines. STRUCTURE analysis indicated the presence of three genetic populations, one of which spanned the international border. This pattern of genetic structure was supported by analysis of molecular variance for both microsatellites and mitochondrial DNA (P

  • RESPONSE OF BIGHORN SHEEP (Ovis Canadensis) TO FERAL HONEY BEES (APIS MELLIFERA) AT WATER
    The Southwestern Naturalist, 2003
    Co-Authors: Walter M. Boyce, Chantal S. O'brien, Esther S. Rubin
    Abstract:

    Abstract We used remote cinematography to evaluate the interactions between feral honey bees (Apis mellifera) and desert bighorn sheep (Ovis Canadensis) at an artificial water source (guzzler) in Anza-Borrego Desert State Park in southern California from July through September 1995. Honey bees, determined by molecular analysis to be non-Africanized (i.e., not A. m. scutellata), were present at the guzzler collecting water from dawn to dusk whenever bighorn sheep were videotaped. Bighorn sheep exhibited behavioral responses (violent head shaking, rapid withdrawal from the water source, and temporary refusal to drink) to honey bees during 62% (66 of 107) of their visits to the guzzler. Bighorn sheep spent significantly (P < 0.001) more time at the guzzler when their visits were interrupted by honey bees than when they were not interrupted. We concluded that honey bees altered the behavior of bighorn sheep and that honey bees and bighorn sheep were competing for water resources at the guzzler.

  • Population subdivision among desert bighorn sheep (Ovis Canadensis) ewes revealed by mitochondrial DNA analysis
    Molecular ecology, 1999
    Co-Authors: Walter M. Boyce, Esther S. Rubin, Rob Roy Ramey, Timothy C. Rodwell, Randall S. Singer
    Abstract:

    We used behavioural observations and mitochondrial DNA (mtDNA) sequence analysis to examine demographic and genetic structure within and among home-range groups of desert bighorn sheep (Ovis Canadensis) ewes in the Peninsular Ranges of southern California, USA. We identified substantial genetic variation in the first 515 bp of the mtDNA control region and determined that seven haplotypes were distributed in a nonrandom fashion among these ewe subpopulations. Although a significant (P < 0.01) amount of mtDNA variation (33%) was partitioned among home-range groups, we did not find strong evidence for matrilineal substructuring within these groups. Based on analyses of molecular variance, and comparisons of behavioural associations and distances between centres of activity, we concluded that within a given home-range group, bighorn sheep ewes generally associate with other ewes based on their availability rather than their matrilineal relationships. Our results also supported the conclusion that multiple ewe subpopulations exist within the Peninsular Ranges, and that these subpopulations are the most basic demographic and genetic units.

  • Pregnancy detection in bighorn sheep (Ovis Canadensis) using a fecal-based enzyme immunoassay.
    Journal of wildlife diseases, 1996
    Co-Authors: Dori L. Borjesson, Walter M. Boyce, Ian A. Gardner, James Deforge, Bill Lasley
    Abstract:

    We developed and validated an enzyme immunoassay for immunoreactive pregnanediol-3-glucuronide (iPdG) in feces to monitor reproductive status in desert and Rocky Mountain bighorn sheep (Ovis Canadensis). Fecal iPdG concentrations were strongly correlated (r = 0.71) with serum progesterone concentrations in paired fecal and blood samples collected from 34 free-ranging desert bighorn sheep. In bimonthly fecal samples collected from 12 captive ewes, fecal iPdG profiles were similar between desert and Rocky Mountain bighorn sheep and we selected a pregnancy detection cutoff value of iPdG ≥1.8 ng/mg feces. Fecal iPdG concentrations always exceeded this cutoff value when samples were collected from about day 60 of pregnancy to a few days before parturition, but values

R. Lee Lyman - One of the best experts on this subject based on the ideXlab platform.

  • Dental enamel hypoplasias in Holocene bighorn sheep (Ovis Canadensis) in eastern Washington state, USA
    Canadian Journal of Zoology, 2018
    Co-Authors: R. Lee Lyman
    Abstract:

    Dental enamel hypoplasias have been documented in extant and fossil mammal species and attributed to several kinds of physiological stress. They have not previously been reported among bighorn sheep (Ovis Canadensis Shaw, 1804). Forty-six (36.8%) of 125 mandibular molars (m1, m2, m3) of bighorn recovered from disturbed Holocene archaeological deposits in eastern Washington state display several kinds of hypoplasias. The exact ontogenetic age of the individual animals when hypoplasias formed cannot be determined. The majority of the hypoplasias occur near the root–enamel junction of the m3, suggesting that most individuals were young adults when the defect formed. Physiological stress associated with reproductive costs, winter nutritional deficits, or both seems likely.

  • Wear stages and crown heights in prehistoric bighorn sheep (Ovis Canadensis) lower molars in eastern Washington state, U.S.A.
    Journal of Archaeological Science: Reports, 2017
    Co-Authors: R. Lee Lyman
    Abstract:

    Abstract Bighorn sheep ( Ovis Canadensis ) remains are often found in western North American archaeological sites. Determination of ontogenetic age of zooarchaeological individuals would allow assessment of season of procurement, herd demography at the time of procurement, and perhaps differential processing. The known dental eruption schedule for bighorn is imprecise for purposes of estimating season of death, and all teeth are erupted when an individual is ~ 42 months old, precluding detailed analysis of herd demography. The tooth wear sequence established by Sebastian Payne for Old World domestic sheep ( Ovis aries ) extends to near the end of an individual's lifespan and is applicable to New World bighorn based on a zooarchaeological sample of 105 mandibular molars. Crown heights and crown widths of the zooarchaeological bighorn molars correlate with one another and with wear stages, suggesting study of a modern sample of bighorn mandibular dentitions from individuals of known ontogenetic age would repay the effort.

  • Mandibular hypodontia and osteoarthritis in prehistoric bighorn sheep (Ovis Canadensis) in eastern Washington State, USA
    International Journal of Osteoarchaeology, 2009
    Co-Authors: R. Lee Lyman
    Abstract:

    Mandibular hypodontia of the p2 was found to occur in 3 out of 21 individual prehistoric Rocky Mountain bighorn sheep (Ovis Canadensis Canadensis) from Moses Coulee Cave in eastern Washington State, similar to its frequency of occurrence in modern bighorn. There is no evidence of lumpy jaw (mandibular osteomyelitis) in the Moses Coulee Cave collection. Evidence from Moses Coulee Cave aligns with the hypothesis that low frequencies of hypodontia and lumpy jaw occur in healthy, evolutionarily old (maintenance) populations in order to maintain the occlusal area and thus maximise efficiency of food procurement and processing. Osteoarthritis was found to occur in 1 out of 70 individual Rocky Mountain bighorn sheep (Ovis Canadensis Canadensis) astragali in the Moses Coulee Cave collection. This prevalence is unsurprising given a population dominated by prime-age individuals. Osteoarthritis was likely selected against given that individuals must be agile to effectively use rugged terrain to escape predation and as a general measure suggests a healthy population. Copyright © 2009 John Wiley & Sons, Ltd.

  • The Holocene history of bighorn sheep (Ovis Canadensis) in eastern Washington state, northwestern USA
    The Holocene, 2009
    Co-Authors: R. Lee Lyman
    Abstract:

    Historical data are incomplete regarding the presence/absence and distribution of bighorn sheep (Ovis Canadensis) in eastern Washington State. Palaeozoological (archaeological and palaeontological) data indicate bighorn were present in many areas there during most of the last 10 000 years. Bighorn occupied the xeric shrub-steppe habitats of the Channeled Scablands, likely because the Scablands provided the steep escape terrain bighorn prefer. The relative abundance of bighorn is greatest during climatically dry intervals and low during a moist period. Bighorn remains tend to increase in relative abundance over the last 6000 years. Bighorn were present in eastern Washington in the nineteenth century, but were largely locally extirpated by the twentieth century. A collection of prehistoric bighorn astragali that likely includes specimens spanning the terminal Pleistocene and the entire Holocene consists of specimens that are, with one exception, the same size as a collection of modern bighorn astragali from...

David A. Jessup - One of the best experts on this subject based on the ideXlab platform.

  • Seroprevalence of two Babesia spp. isolates in selected bighorn sheep (Ovis Canadensis) and mule deer (Odocoileus hemionus) populations in California.
    Journal of wildlife diseases, 1995
    Co-Authors: Anne M. Kjemtrup, David A. Jessup, Ian A. Gardner, John W. Thomford, Patricia A. Conrad, Walter M. Boyce
    Abstract:

    Sera from 111 bighorn sheep (Ovis Canadensis) and 95 mule deer (Odocoileus hem-ionus) were tested using an indirect immunofluorescence assay for antibodies to two isolates of Babesia spp. recently obtained from these hosts in California (USA). The study populations were from six locations: three areas of real or potential sympatry of bighorn sheep and deer, one area with deer only, and two areas with bighorn sheep only. Antibody titers from seroreactive individuals were similar with both babesial isolate antigens (P < 0.05), and seroprevalence was highest in the areas of host sympatry. A moderate to high seroprevalence (≥ 30%) in some of the study populations was evidence that babesial parasites may be common in bighorn sheep and mule deer in some areas of California.

  • Geographic analysis of pathogen exposure in bighorn sheep (Ovis Canadensis).
    Journal of wildlife diseases, 1994
    Co-Authors: Lee F. Elliott, Walter M. Boyce, Richard K. Clark, David A. Jessup
    Abstract:

    Antibody responses were examined among 998 bighorn sheep (Ovis Canadensis) in California (USA) to determine spatial patterns of pathogen exposure. Using a shifting frame analysis, a specific geographic region was delineated that contained bighorn sheep with higher (P < 0.05) levels of multiple exposure (antibodies detected against ≥two pathogens), as well as higher prevalence values for eight of ten individual pathogens. This region in southwestern California encompassed all of the peninsular populations of bighorn sheep recently proposed for listing as endangered by the U.S. Fish and Wildlife Service.

  • RESTRICTION ENDONUCLEASE ANALYSIS OF HERPESVIRUSES ISOLATED FROM TWO PENINSULAR BIGHORN SHEEP (Ovis Canadensis CREMNOBATES)
    Journal of wildlife diseases, 1993
    Co-Authors: Richard K. Clark, Cecelia A. Whetstone, Anthony E. Castro, Mark M. Jorgensen, Jill F. Jensen, David A. Jessup
    Abstract:

    In 1989, herpesviruses were isolated from nasal swabs taken from two peninsular bighorn sheep (Ovis Canadensis cremnobates) in the Anza-Borrego Desert State Park, San Diego County, California (USA). Using restriction endonuclease analysis (REA) with Pst1 enzyme, each isolate was found to be similar to the Cooper strain of infectious bovine rhinotracheitis virus (IBRV). The REA patterns of the two herpesviruses from bighorn sheep were typical of either field strains or vaccine strains of IBRV commonly associated with cattle in the USA.

  • A RETROSPECTIVE SEROLOGIC SURVEY FOR ANAPLASMA SPP. INFECTION IN THREE BIGHORN SHEEP (Ovis Canadensis) POPULATIONS IN CALIFORNIA
    Journal of wildlife diseases, 1993
    Co-Authors: David A. Jessup, Vernon C. Bleich, Will L. Goff, David Stiller, Michael N. Oliver, Walter M. Boyce
    Abstract:

    Using an indirect immunofluorescence assay, we determined the prevalence of Anaplasma-reactive antibody in three herds of bighorn sheep, each a different subspecies and occupying a different habitat in California (USA). Antibodies to Anaplasma spp. were identified in none of twenty California bighorn (Ovis Canadensis californiana) sampled from the Mt. Baxter herd, 11 of 17 peninsular bighorn (O. Canadensis cremnobates) sampled in the Santa Rosa Mountains, and all 20 desert bighorn (O. Canadensis nelsoni) sampled at Old Dad Peak/Kelso Mountains. Based on an assay and an adsorption technique, the titers most likely were due to Anaplasma Ovis. The presence and species of tick vectors in each of the habitats, and the presence or absence of deer or livestock were identified as factors potentially influencing seroprevalence of antibodies.

  • SURVEY OF PATHOGEN EXPOSURE AMONG POPULATION CLUSTERS OF BIGHORN SHEEP (Ovis Canadensis) IN CALIFORNIA
    Journal of Zoo and Wildlife Medicine, 1993
    Co-Authors: Richard K. Clark, Walter M. Boyce, David A. Jessup, Lee F. Elliott
    Abstract:

    Nine hundred ninety-three bighorn sheep (Ovis Canadensis nelsoni, n = 719; 0. c. cremnobates, n = 158; 0. c. californiana, n = 116) from 50 herds in California were captured between 1978 and 1990 and tested for exposure to selected potential pathogens. Seropositive an tibody responses were detected against bluetongue virus (13%), bovine herpesvirus 1 (< 1%), bovine respiratory syncytial virus (7%), bovine virus diarrhea-mucosal disease virus (7%), contagious ec thyma virus (34%), epizootic hemorrhagic disease virus (18%), parainfluenza-3 virus (10%), Ana plasma spp. (24%), Leptospira interrogans serovars (4%), Chlamydia psittaci (31%), Toxoplasma gondii (22%), and Psoroptes spp. (18%). Because fewer than 10 samples were collected from most of the bighorn populations, the 50 herds were grouped into 14 clusters to facilitate analysis of pathogen distribution across the state. Analysis of clusters indicated that these 12 pathogens were equally distributed (presence vs. absence of seropositive individuals) between populations in north ern and those in southern California. However, a ranking procedure based on pathogen prevalence among clusters indicated that the level of pathogen exposure was higher in bighorn sheep in southern California, an area where the decline of some populations has been attributed to infectious diseases.

Sonia Gallina - One of the best experts on this subject based on the ideXlab platform.

Mi. W. Miller - One of the best experts on this subject based on the ideXlab platform.

  • Assessing Timing and Causes of Neonatal Lamb Losses in a Bighorn Sheep (Ovis Canadensis Canadensis) Herd via Use of Vaginal Implant Transmitters
    Journal of wildlife diseases, 2017
    Co-Authors: Jamin L. Grigg, Mi. W. Miller, Halcyon J Killion, Lisa L Wolfe, Karen A. Fox, Jessica Jennings-gaines, Brian P. Dreher
    Abstract:

    Abstract We evaluated the use of vaginal implant transmitters (VITs) as a means of detecting, capturing, and radio collaring Rocky Mountain bighorn sheep (Ovis Canadensis Canadensis) lambs to estimate survival and to facilitate carcass recovery to assess causes of mortality. We focused on one of several bighorn herds in Colorado, US, suffering from depressed recruitment that was not preceded by a classic all-age die-off. We captured, radio-collared, diagnosed pregnancy by ultrasound examination, and inserted VITs into 15 pregnant ewes from a herd residing near Granite, Colorado. We were subsequently able to collar a lamb from each of 13 VITs, and two additional lambs opportunistically from ewes without transmitters. As lambs died, we recovered and submitted carcasses for necropsy and laboratory assessment. All lambs captured and one additional lamb (carcass found opportunistically) were dead by about 130 d of age: 11 died of apparent pneumonia (all within 8−10 wk of age), one died from trauma after being ...

  • how respiratory pathogens contribute to lamb mortality in a poorly performing bighorn sheep Ovis Canadensis herd
    Journal of Wildlife Diseases, 2017
    Co-Authors: Mary E. Wood, Mi. W. Miller, Jessica Jenningsgaines, Halcyon J Killion, Karen A. Fox, Sierra Amundson, William H. Edwards
    Abstract:

    Abstract We evaluated bighorn sheep (Ovis Canadensis) ewes and their lambs in captivity to examine the sources and roles of respiratory pathogens causing lamb mortality in a poorly performing herd. After seven consecutive years of observed December recruitments of <10%, 13 adult female bighorn sheep from the remnant Gribbles Park herd in Colorado, US were captured and transported to the Thorne-Williams Wildlife Research Center in Wyoming in March 2013. Ewes were sampled repeatedly over 16 mo. In April 2014, ewes were separated into individual pens prior to lambing. Upon death, lambs were necropsied and tested for respiratory pathogens. Six lambs developed clinical respiratory disease and one lamb was abandoned. Pathology from an additional six lambs born in 2013 was also evaluated. Mycoplasma ovipneumoniae, leukotoxigenic Mannheimia spp., leukotoxigenic Bibersteinia trehalosi, and Pasteurella multocida all contributed to lamb pneumonia. Histopathology suggested a continuum of disease, with lesions typical...

  • How Respiratory Pathogens Contribute to Lamb Mortality in a Poorly Performing Bighorn Sheep ( Ovis Canadensis ) Herd.
    Journal of wildlife diseases, 2016
    Co-Authors: Mary E. Wood, Mi. W. Miller, Halcyon J Killion, Karen A. Fox, Jessica Jennings-gaines, Sierra Amundson, William H. Edwards
    Abstract:

    Abstract We evaluated bighorn sheep (Ovis Canadensis) ewes and their lambs in captivity to examine the sources and roles of respiratory pathogens causing lamb mortality in a poorly performing herd. After seven consecutive years of observed December recruitments of

  • Paranasal Sinus Masses of Rocky Mountain Bighorn Sheep (Ovis Canadensis Canadensis)
    2016
    Co-Authors: Karen A. Fox, Sarah K Wootton, Sandra L. Quackenbush, Ivy K. Levan, Mi. W. Miller, Lisa L Wolfe, Terry R Spraker
    Abstract:

    This article describes 10 cases of paranasal sinus masses in Rocky Mountain bighorn sheep (Ovis Canadensis Canadensis). Among 21 bighorns that were examined from 11 herds in Colorado, 10 individuals (48%) from 4 herds (36%) had masses arising from the paranasal sinuses. Affected animals included 9 of 17 females (53%) and 1 of 4 males (25%), ranging in age from approximately 2 years to greater than 10 years. Defining gross features of these masses included unilateral or bilateral diffuse thickening of the respiratory lining of the maxillary and/or frontal sinuses, with abundant seromucinous exudate in the affected sinus cavities. Defining histologic features of these masses included chronic inflammation and proliferation of mesenchymal and epithelial cells of the mucosa and submucosa. Epithelial changes included hyperplasia of mucosal epithelium, hyperplasia of submucosal glands and ducts, and neoplasia (adenocarcinoma). Mesenchymal changes included submucosal myxedema, submucosal fibroplasia/ fibrosis, bone destruction, and neoplasia (myxomatous fibroma). Specific immunohistochemistry and polymerase chain reaction for Jaagsiekte sheep retrovirus and enzootic nasal tumor virus were performed with negative results. Keyword

  • Experimental Transmission of Bighorn Sheep Sinus Tumors to Bighorn Sheep (Ovis Canadensis Canadensis) and Domestic Sheep.
    Veterinary Pathology, 2016
    Co-Authors: Karen A. Fox, Sarah K Wootton, Ivy K. Levan, Mi. W. Miller, Terry R Spraker, A. Marolf, N. Rouse, Sandra L. Quackenbush
    Abstract:

    Bighorn sheep sinus tumors are a recently described disease affecting the paranasal sinuses of Rocky Mountain bighorn sheep (Ovis Canadensis Canadensis). Several features of this disease suggest an infectious cause, although a specific etiologic agent has not been identified. To test the hypothesis that bighorn sheep sinus tumors are caused by an infectious agent, we inoculated 4 bighorn sheep lambs and 4 domestic sheep lambs intranasally with a cell-free filtrate derived from a naturally occurring bighorn sheep sinus tumor; we held 1 individual of each species as a control. Within 18 months after inoculation, all 4 inoculated domestic sheep (100%) and 1 of the 4 inoculated bighorn sheep (25%) developed tumors within the ethmoid sinuses or nasal conchae, with features similar to naturally occurring bighorn sheep sinus tumors. Neither of the uninoculated sheep developed tumors. Histologically, the experimentally transmitted tumors were composed of stellate to spindle cells embedded within a myxoid matrix, with marked bone production. Tumor cells stained positively with vimentin, S100, alpha smooth muscle actin, and osteocalcin, suggesting origin from a multipotent mesenchymal cell. A periosteal origin for these tumors is suspected. Immunohistochemical staining for the envelope protein of JSRV (with cross-reactivity to ENTV) was equivocal, and PCR assays specific for these agents were negative.

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