Attainment of early puberty in female black-tailed deer. (Odocoileus hemionus columbianus).

Female black-tailed deer fawns were hand-raised until four months of age and bred to bucks in their first fall. Over 50% conceived and subsequently gave birth to single fawns. Conceptions occurred later than for wild adults but at weights which equalled the weights of the heaviest wild fawns. A high proportion of the fawns born to fawn does died due to presumed lactation failure. Further work is continuing on the factors governing puberty attainment in this species.     

Columbian black-tailed deer (Odocoileus hemionus columbianus) as hosts for Borrelia spp. in northern California

The prevalence of infection of Columbian black-tailed deer (Odocoileus hemionus columbianus) with Borrelia spp. was evaluated in an area of northwestern California (USA) where Lyme disease is endemic and the relapsing-fever group spirochete Borrelia coriaceae is enzootic, and in a far-removed comparison area having a disparate climate and lower density of vector ticks. Blood samples collected from both deer herds in 1987, 1988, and from 2000-02 were assayed for borrelial infection with microscopic and molecular methods. Serum specimens from two (5%) of 39 deer from the Dye Creek Preserve in Tehama County versus 13 (20%) of 64 animals from the Hopland Research and Extension Center (HREC) in Mendocino County, California were polymerase chain reaction (PCR) test positive for B. burgdorferi sensu lato. DNA sequencing analyses revealed that eight animals were infected with B. bissettii, six with three unclassified genotypes, and one with B. burgdorferi sensu stricto. One serum sample (2%) from HREC was positive for a relapsing-fever group spirochete that had a 16S rRNA sequence homology of 99% with the C053 type strain of B. coriaceae. Spirochetes undetermined to geno-species were detected in thick-blood drops prepared from three (8%) of 36 deer from the HREC by direct immunofluorescence. Adults of the hippoboscid flies Lipoptena depressa (n=73) and Neolipoptena ferrisi (n=24), the Pacific Coast tick (Dermacentor occidentalis) (n=22), and the western black-legged tick (Ixodes pacificus) (n=1) that had been removed from deer from both study areas in 2002 were PCR test negative for borreliae. The occurrence of diverse borreliae in deer from northern California confounds and, consequently, reduces the utility of borrelial serosurveys for detecting specific genospecies, unless they are complemented by more specific assays (e.g., immunoblotting, PCR/sequencing analysis).     

Changes in gonadotrophin and ovarian hormone levels during the estrous cycle of black-tailed deer (Odocoileus hemionus columbianus)

Daily blood samples over a fifteen day period were obtained from two adult female black-tailed deer and circulating levels of progesterone, estrogens, luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin were measured by radioimmunoassay. LH levels showed an apogee at the time when there was observed estrous behaviour. The length of the estrous cycle appeared to be 7 days. Progesterone levels peaked just subsequent to the LH peak. High estrogen levels coincided with high progesterone and prolactin levels. FSH reached maximum levels prior to peak estrogen levels. LH and FSH levels reached maxima on different days. There were two steroid peaks between the LH apogees.     

Effects of Cephenemyia spp. (Diptera: Oestridae) on the nasopharynx of black-tailed deer (Odocoileus hemionus columbianus)

A study was conducted to determine gross and microscopic tissue changes in the nasopharynx of black-tailed deer (Odocoileus hemionus columbianus) infected with nasal bot fly larvae (Cephenemyia spp.). Paired retropharyngeal recesses were the preferred sites for the growing second and third stage larvae of two species of Cephenemyia (C. apicata and C. jellisoni). Retropharyngeal recesses distended into "pouches" that harbored up to 30 larvae. Pouches were oriented caudal-laterally toward the basisphenoid bone of the cranium. Lateral support of the pouch mass was provided by the stylohyoid bone. The laryngeal orifice was never occluded by the enlarged recesses. The distal pouch wall was relatively thin and remained uniform in thickness as expansion progressed. Occasionally, aberrant larvae were found protruding through the distal wall of the pouch. Disruption of the epithelium and submucosa by larval mouth hooks and integumentary spines were examined by scanning electron microscopy. Histological examination of infected recesses revealed substantial loss of epithelium and mucous glands. Enlargement of recesses into pouches resulted from fibrosis. Healing occurred after larvae egressed from the pouches. Degenerating mucous glands, epithelial metaplasia, epithelial desquamation, and intense inflammation were found near larvae. An eosinophilic exudate with a mixture of macrophages and erythrocytes was present in the lumen of the pouch. The presence of larvae within the pouch inhibited secondary bacterial infection and suppuration. Infection by larvae caused severe local trauma and intense tissue response.     

Trypanosomes from mule deer, Odocoileus hemionus in Wyoming.

Examination of mule deer, Odocoileus hemionus, from Wyoming in Spring, 1974 (8) and in Winter of 1974-75 (8) revealed trypanosomes in all 16 deer. Spring samples showed dividing epimastigotes as well as normal bloodstream forms. Winter samples showed only normal blood stream forms. These differences are considered to be seasonally related.     

Testicular atrophy in Columbian black-tailed deer in California.

During an 18-year period, 4.1% (34/831) of male deer (Odocoileus hemionus columbianus) killed on a field station during the autumn hunting season had velvet-covered, often misshapen antlers, and at least two deer had testicular atrophy (gonads from most deer were not available for examination). Testes from six similarly affected deer and several normal deer were compared histologically. Lesions ranged from hypocellularity of the semeniferous tubules and relative hyperplasia or degeneration of interstitial cells to complete connective tissue replacement of the testicular parencyma. Chronic vascular changes were present in several testes. The etiology and pathogenesis of the lesions were not determined.     

Parelaphostrongylus odocoilei in Columbian black-tailed deer from Oregon

Documenting the occurrence of Parelaphostrongylus odocoilei has historically relied on the morphological examination of adult worms collected from the skeletal muscle of definitive hosts, including deer. Recent advances in the knowledge of protostrongylid genetic sequences now permit larvae to be identified. Dorsal-spined larvae (DSLs) collected in 2003-2004 from the lung and feces of six Columbian black-tailed deer (Odocoileus hemionus columbianus) from Oregon were characterized genetically. The sequences from unknown DSLs were compared to those from morphologically validated adults and larvae of P. odocoilei at both the second internal transcribed spacer (ITS-2) of ribosomal DNA and the mitochondrial cytochrome oxidase II gene. We provide the first unequivocal identification of P. odocoilei in Columbian black-tailed deer from Oregon. The broader geographic distribution, prevalence, and pathology of P. odocoilei are not known in populations of Oregon deer.     

Demodicosis in a mule deer (Odocoileus hemionus hemionus) from Saskatchewan, Canada

Infestation of deer with Demodex spp. mites has been described in white-tailed deer (Odocoileus virginianus) and in Columbian black-tailed deer (Odocoileus hemionus columbianus) in North America, as well as in four species of deer in Europe. We describe Demodex sp. infestation in an adult female mule deer (Odocoileus hemionus hemionus) with skin lesions found dead near Saskatoon, Saskatchewan, Canada. This is believed to be the first report of demodicosis in mule deer.     

Experimental Fascioloides magna infections of mule deer (Odocoileus hemionus hemionus).

Six mule deer (Odocoileus hemionus hemionus) and one white-tailed deer (Odocoileus virginianus), approximately 5-mo-old, each were inoculated orally with 500 metacercariae of Fascioloides magna. All mule deer died from liver fluke infection between 69 and 134 days (mean = 114, SE = 9.9) after inoculation. Between 38 and 326 immature F. magna (mean = 102, SE = 45.5) were recovered from each deer at necropsy. Flukes were present in livers, lungs, and free in pleural and peritoneal spaces. Infection was characterized by necrotizing hepatitis, fibrosing peritonitis and pleuritis, and hematin pigment accumulation in liver, lung, and many other internal organs. Eggs of F. magna first were detected in feces of the white-tailed deer 28 wk after inoculation, and weekly thereafter until the healthy deer was euthanized at 31 wk. At necropsy, 205 F. magna, including 12 encapsulated mature and 193 nonencapsulated immature flukes were recovered from liver, lungs, and free in abdominal and thoracic spaces of the white-tailed deer. Based on these results, F. magna may be fatal to mule deer within 5 mo of infection. Like domestic sheep and goats, mule deer may be highly susceptible to infection, and it is unlikely mule deer can survive infection with large numbers of F. magna.     

Hybrid swarm between divergent lineages of mule deer (Odocoileus hemionus)

Studies of hybrid zones have revealed an array of evolutionary outcomes, yet the underlying structure is typically characterized as one of three types: a hybrid zone, a hybrid swarm or a hybrid taxon. Our primary objective was to determine which of these three structures best characterizes a zone of hybridization between two divergent lineages of mule deer (Odocoileus hemionus), mule deer and black-tailed deer. These lineages are morphologically, ecologically and genetically distinct, yet hybridize readily along a zone of secondary contact between the east and west slopes of the Cascade Mountains (Washington and Oregon, USA). Using microsatellite and mitochondrial DNA, we found clear evidence for extensive hybridization and introgression between lineages, with varying degrees of admixture across the zone of contact. The pattern of hybridization in this region closely resembles a hybrid swarm; based on data from 10 microsatellite loci, we detected hybrids that extend well beyond the F1 generation, did not detect linkage disequilibrium at the centre of the zone and found that genotypes were associated randomly within the zone of contact. Introgression was characterized as bidirectional and symmetric, which is surprising given that the zone of contact occurs along a sharp ecotone and that lineages are characterized by large differences in body size (a key component of mating success). Regardless of the underlying mechanisms promoting hybrid swarm maintenance, it is clear that the persistence of a hybrid swarm presents unique challenges for management in this region.