Sufentanil and xylazine immobilization of Rocky Mountain elk

From October 2009 through July 2010, five captive, 3-yr-old, female Rocky Mountain elk (Cervus elaphus) and nine free-ranging elk (one male, eight female) were immobilized with 0.1 mg/kg sufentanil plus 0.5 mg/kg xylazine which was antagonized with 1 mg/kg naltrexone and 2 mg/kg tolazoline. Induction and recovery times averaged 4.9 ± 0.3 min and 3.9 ± 0.4 min, respectively. Physiologic and blood gas parameters as well as bispectral index (BIS) were measured on the captive elk every 10 min for 30 min. Immobilization induced profound hypoxemia via hypoventilation and ventilation-perfusion mismatching as demonstrated by depressed partial pressure of arterial oxygen (P(a)O(2)) and increased partial pressure of arterial carbon dioxide (P(a)CO(2)). The only values to significantly (P<0.05) change over time were base excess (BE), bicarbonate (HCO(3)), and lactate. Bispectral index is a measure of anesthetic depth. The average BIS value over the 30 min period (59.1 ± 2.4) was higher than the BIS value at the approximate point where elk lose consciousness, which indicated that this drug combination produced neuroleptanalgesia but not general anesthesia. Sufentanil and xylazine provided effective remote immobilization in elk and could be substituted for carfentanil or thiafentanil and xylazine should the need arise.     

Mortality of Rocky Mountain elk in Michigan due to meningeal worm

Mortality from cerebrospinal parelaphostrongylosis caused by the meningeal worm (Parelaphostrongylus tenuis) has been hypothesized to limit elk (Cervus elaphus nelsoni) populations in areas where elk are conspecific with white-tailed deer (Odocoileus virginianus). Elk were reintroduced into Michigan (USA) in the early 1900s and subsequently greatly increased population size and distribution despite sympatric high-density (>or=12/km2) white-tailed deer populations. We monitored 100 radio-collared elk of all age and sex classes from 1981-94, during which time we documented 76 mortalities. Meningeal worm was a minor mortality factor for elk in Michigan and accounted for only 3% of mortalities, fewer than legal harvest (58%), illegal kills (22%), other diseases (7%), and malnutrition (4%). Across years, annual cause-specific mortality rates due to cerebrospinal parelaphostrongylosis were 0.033 (SE=0.006), 0.029 (SE=0.005), 0.000 (SE=0.000), and 0.000 (SE=0.000) for calves, 1-yr-old, 2-yr-old, and >or=3-yr-old, respectively. The overall population-level mortality rate due to cerebrospinal parelaphostrongylosis was 0.009 (SE=0.001). Thus, meningeal worm had little impact on elk in Michigan during our study despite greater than normal precipitation (favoring gastropods) and record (>or=14 km2) deer densities. Further, elk in Michigan have shown sustained population rates-of-increase of >or=18%/yr and among the highest levels of juvenile production and survival recorded for elk in North America, indicating that elk can persist in areas with meningeal worm at high levels of population productivity. It is likely that local ecologic characteristics among elk, white-tailed deer, and gastropods, and degree of exposure, age of elk, individual and population experience with meningeal worm, overall population vigor, and moisture determine the effects of meningeal worm on elk populations.     

Snakebite in captive Rocky Mountain elk (Cervus elaphus nelsoni)

Eight cases of snakebite occurred in seven of 11 captive Rocky Mountain elk (Cervus elaphus nelsoni) during June and July 1987. Severity of reactions to envenomation varied; affected elk presented with combinations of signs that included painful swelling restricted to the face and muzzle, submandibular edema, inspiratory dyspnea, epistaxis, frothy, blood-tinged nasal discharge, epiphora, anorexia and anxiousness or depression. We observed puncture wounds in only two cases. Treatment consisted of dexamethasone (about 0.1 mg/kg subcutaneously, single dose) and procaine penicillin G (about 25,000 IU/kg subcutaneously, once or twice daily, for 5 to 6 days), as well as revaccination using clostridium and tetanus toxoids. Swelling resolved and elk recovered in 3 to 5 days without complications. Using immunodiffusion, we detected serum antibodies to prairie rattlesnake (Crotalus viridis viridis) venom in six of seven affected elk, demonstrating seroconversion in three cases and anamnesis in one elk bitten twice. Venom was undetectable in any serum samples using similar techniques.     

Gene expression alterations in Rocky Mountain elk infected with chronic wasting disease

Chronic wasting disease (CWD) is an invariably fatal neurologic disease that naturally infects mule deer, white tailed deer and elk. The understanding of CWD neurodegeneration at a molecular level is very limited. In this study, microarray analysis was performed to determine changes in the gene expression profiles in six different tissues including brain, midbrain, thalamus, spleen, RPLN and tonsil of CWD-infected elk in comparison to non-infected healthy elk, using 24,000 bovine specific oligo probes. In total, 329 genes were found to be differentially expressed (> 2.0-fold) between CWD negative and positive brain tissues, with 132 genes upregulated and 197 genes downregulated. There were 249 DE genes in the spleen (168 up- and 81 downregulated), 30 DE genes in the retropharyngeal lymph node (RPLN) (18 up- and 12 downregulated), and 55 DE genes in the tonsil (21 up- and 34 downregulated). Using Gene Ontology (GO), the DE genes were assigned to functional groups associated with cellular process, biological regulation, metabolic process, and regulation of biological process. For all brain tissues, the highest ranking networks for DE genes identified by Ingenuity Pathway Analysis (IPA) were associated with neurological disease, cell morphology, cellular assembly and organization. Quantitative real-time PCR (qRT-PCR) validated the expression of DE genes primarily involved in different regulatory pathways, including neuronal signaling and synapse function, calcium signaling, apoptosis and cell death and immune cell trafficking and inflammatory response. This is the first study to evaluate altered gene expression in multiple organs including brain from orally infected elk and the results will improve our understanding of CWD neurodegeneration at the molecular level.     

Gene expression alterations in Rocky Mountain elk infected with chronic wasting disease

Chronic wasting disease (CWD) is an invariably fatal neurologic disease that naturally infects mule deer, white tailed deer and elk. The understanding of CWD neurodegeneration at a molecular level is very limited. In this study, microarray analysis was performed to determine changes in the gene expression profiles in six different tissues including brain, midbrain, thalamus, spleen, RPLN and tonsil of CWD-infected elk in comparison to non-infected healthy elk, using 24,000 bovine specific oligo probes. In total, 329 genes were found to be differentially expressed (> 2.0-fold) between CWD negative and positive brain tissues, with 132 genes upregulated and 197 genes downregulated. There were 249 DE genes in the spleen (168 up- and 81 downregulated), 30 DE genes in the retropharyngeal lymph node (RPLN) (18 up- and 12 downregulated), and 55 DE genes in the tonsil (21 up- and 34 downregulated). Using Gene Ontology (GO), the DE genes were assigned to functional groups associated with cellular process, biological regulation, metabolic process, and regulation of biological process. For all brain tissues, the highest ranking networks for DE genes identified by Ingenuity Pathway Analysis (IPA) were associated with neurological disease, cell morphology, cellular assembly and organization. Quantitative real-time PCR (qRT-PCR) validated the expression of DE genes primarily involved in different regulatory pathways, including neuronal signaling and synapse function, calcium signaling, apoptosis and cell death and immune cell trafficking and inflammatory response. This is the first study to evaluate altered gene expression in multiple organs including brain from orally infected elk and the results will improve our understanding of CWD neurodegeneration at the molecular level.     

Nematode-Trapping Fungi in Biological Control of Dictyocaulus viviparus

Larvae of the cattle lungworm Dictyocaulus viviparus were cultured in experimental units of 200 g cattle faeces placed in semi-transparent trays in the laboratory. In each of 4 experimental series using this experimental unit, chlamydospores (chl) of the nematode-trapping fungus Duddingtonia flagrans were admixed to half of the faecal cultures in a concentration of 50.000 chl/g. In all 4 series there was a significant reduction in the development and subsequent release of infective lungworm larvae from faecal cultures containing chlamydospores. The average reduction in larval release, caused by fungal spores, was 86%.     

Morphology of inhibited larvae of the bovine lungworm Dictyocaulus viviparus.

Some morphological features of inhibited fourth stage (L4) and fourth moult larvae (4M) of the bovine lungworm Dictyocaulus viviparus are described. Inhibition was induced by maintaining the third stage larvae (L3) for 6 weeks at 4 degrees C. Inhibited fourth stage (L4) and fourth moult larvae (4M) were collected by perfusion of the lungs of experimentally infected calves after necropsy at 15 and 68 days post infection (d.p.i.), respectively. Inhibited 4M, isolated at 68 d.p.i., were about ten times larger than inhibited L4 isolated at 15 d.p.i.     

Survival and cause-specific mortality of female Rocky Mountain elk exposed to human activity

Animal populations are becoming increasingly exposed to human activity as human populations expand and demand for energy resources (e.g., coal, oil and natural gas) increases. We initiated this study to document survival and cause-specific mortality patterns of female Rocky Mountain elk (Cervus elaphus) exposed to increasing levels of human activity. We fitted 184 females with VHF or GPS collars over 4 years and used the Kaplan–Meier survival estimator to calculate annual survival rates. We used multinomial logistic regression to assess differences in cause-specific mortality and generalized linear mixed models to determine how probability of survival was structured during hunting season; both analyses examined a suite of 5 covariates (i.e., age, year, extent of space use, cover, and human footprint) as potentially influencing cause-specific mortality and survival probability. Annual probability of survival averaged 0.8 (±0.02 SE) over 4 years but averaged 0.91 (±0.03 SE) when harvest mortality was excluded, which was the most significant source of mortality in most years ( [`(x)] = 0.13 ±0.02 \textSE \bar{x} = 0.13 \pm 0.02\,{\text{SE}} ). We found no difference between cause-specific mortality sources relative to elk that survived during the hunting season (χ ₁₀² = 5.79, P = 0.832). The probability of a female surviving during hunting season was negatively influenced by age, year, extent of space use, cover, and human footprint. We found evidence that human activity may have influenced annual rates of natural survival (i.e., exclusive of hunting mortality) and probability of survival during the hunting season. We note that this study occurred largely on privately owned and managed residential and ranch land and focused on female elk; we acknowledge that survival rate and cause-specific patterns of mortality may vary as a function of land ownership (private vs. public), demographic status, and management and harvest practices. While temporal and spatial scales of 1 week may be sufficient to describe patterns of direct mortality during hunting season, broad temporal or spatial scale analyses may be needed to address natural mortality during other seasons.     

The effects of elk on aspen in the winter range in Rocky Mountain National Park

National parks face problems in managing wild ungulates and their forage resources, including small park sizes and incomplete protection of winter ranges, absence of major predators, and influences from exterior management activities Our study focuses on the effects of elk Cervus elaphus browsing on aspen Populus tremuloides in the elk winter range of Rocky Mountain National Park Elk can prevent successful regeneration of aspen by suckers, and increase the mortality of established trees Here we quantify the effect of elk on aspen in the elk winter range of the park particularly since the adoption of a policy of “natural regulation” in 1968 We collected a stratified-random sample of aspen cohorts in the elk winter range, and also inside two long-term exclosures In each cohort we tallied live and dead trees by diameter, recorded the height and percentage of stem surface covered by bark-stripping, and estimated the date of regeneration of the cohort using increment cores We also tallied live and dead aspen suckers (young trees < 2 5 in tall) by height and the number of live and dead branches on each sucker Aspen outside the exclosures are declining as evidenced by 1) high mortality among established trees, including entire stands that are dead, 2) low density of live suckers, insufficient to regenerate the stand, 3) suckers that are excessively branched and seldom surviving to reach tree height, and 4) almost no cohort regeneration since adoption of natural regulation Exclosures and early photos of the elk winter range suggest these are anomalous conditions Over the last century, aspen cohorts regenerated only when there were fewer than ca 600 elk on the park's elk winter range, far fewer than the present estimated 1600 head Fire suppression, natural succession, fluctuations in beaver populations, climatic fluctuations, and other factors are of no or lesser importance than elk in the regeneration and survival of aspen cohorts on the elk winter range The decline of aspen is a concern when management is focused on the ecosystem scale rather than simply the scale of wildlife and their primary forage resources     

Brucellosis in elk I. Serologic and bacteriologic survey in Wyoming.

Incidence of brucellosis in elk (Cervus canadensis) on two winter feedgrounds in Wyoming was examined over a 5-year period by testing serum samples using the standard plate agglutination (SPT) buffered Brucella antigen (BBA), rivanol (Riv) and complement fixation (CFT) tests. Thirty-one percent of 1,165 elk were positive by defined criteria. Considering each test individually, only 29% (106) of 370 positive sera would have been classified as reactors by the SPT, 83% (307) by the BBA test and 86% (314) by the Riv test. The CFT would have identified 85% (267) of 332 positive samples on which it was used. Brucella abortus, type 1, was isolated from 17 of 45 elk necropsied. The SPT identified 59% (10) of these as reactors, the BBA test 94% (16) and the Riv test 88% (15). The CFT identified nine of nine (100%) on which it was used. Prevalence of sero-positive animals increased with age. Brucellosis has been present in one of the two elk herds since at least 1930, and the incidence of infection among mature females in both herds was approximately 50% during this study. No single serologic test should be relied upon to diagnose brucellosis in elk.     

Abiotic,bottom-up,and top-down influences on recruitment of Rocky Mountain elk in Oregon: A retrospective analysis

Understanding the relative effects of the many factors that may influence recruitment of ungulates is fundamental to managing their populations. Over the last 4 decades, average recruitment in some populations of elk (Cervus elaphus) in Oregon, USA declined from >50 to <20 juveniles per 100 females, and several competing hypotheses address these declines. We developed a priori models and constructed covariates spanning 1977–2005 from hunter-killed elk, elk population estimates, cougar harvest, and weather statistics to evaluate abiotic, bottom-up, and top-down factors that may explain annual variation and long-term trends of pregnancy, juveniles-at-heel in late autumn, and recruitment of juvenile elk in spring. In models of pregnancy status, August precipitation, age, and cougar index had positive effects, whereas previous year (t − 1) winter severity or winter precipitation_(t−1) and elk density had negative effects. In models of juvenile-at-heel in late autumn, August precipitation, August precipitation_(t−1), cougar index × elk density_(t−1), and age had positive effects, whereas cougar index, elk density_(t−1), and winter precipitation_(t−1) had negative effects. Juvenile recruitment was best explained by positive effects of August precipitation_(t−1), lactation rate, and cougar index × elk density_(t−1) and negative effects of cougar index and elk density_(t−1). Winter severity, precipitation, and temperature were not significant in explaining variation in elk recruitment. Annual variation in pregnancy, juvenile-at-heel, and recruitment was most influenced by August precipitation, whereas long-term trends in recruitment were most influenced by cougar densities with relatively weak effects of elk density. These results provide insight into causes of year-to-year and long-term trends of elk recruitment and provide a basis for more rigorous evaluation of factors affecting recruitment of elk. © 2012 The Wildlife Society.     

Psoroptic scabies in Rocky Mountain bighorn sheep (Ovis canadensis canadensis) from Wyoming

Thirteen Rocky Mountain bighorn sheep (Ovis canadensis canadensis) with clinical signs of psoroptic scabies were captured in Wyoming. Signs included droopy ears, depilation on the head and neck, and exudate in the ears. Mites were identified as either Psoroptes cervinus or P. equi. Two ewes with scabies at the time of original capture had no clinical signs of mite infection 1 and 2 yr later.     

Molecular characterization of the Rocky Mountain elk (Cervus elaphus nelsoni) PRNP putative promoter

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) affecting deer (Odocoileus spp.), moose (Alces alces), and Rocky Mountain elk (Cervus elaphus nelsoni). Leucine homozygosity at elk PRNP codon 132 has been associated with reduced CWD susceptibility. However, naturally acquired CWD has been detected in elk possessing the 132 Leu/Leu genotype. Recent human and bovine studies indicate that PRNP regulatory polymorphisms may also influence TSE occurrence. Therefore, we generated sequences for the elk PRNP putative promoter (2.2 kb), exon 1 (predicted; 54 bp), intron 1 (predicted; 193 bp), and exon 3 (771 bp). Promoter prediction analysis using CpGProD yielded a single elk PRNP promoter that was homologous to regions of known promoter activity in cow and sheep. Molecular interrogation of the elk PRNP putative promoter revealed 32 diallelic single-nucleotide polymorphisms (SNPs). No variation was detected within the predicted exon 1 or intron 1 sequences. Evaluation of elk PRNP exon 3 revealed 3 SNPs (63Y, 312R, 394W-->Met/Leu). Bayesian haplotype reconstruction resulted in 3 elk PRNP haplotypes, with complete linkage disequilibrium observed between all PRNP putative promoter SNPs and codon 132. The results of this study provide the initial genomic foundation for future comparative and haplotype-based elk PRNP studies.