Rabies in a pronghorn antelope, Antilocapra americana

A ten week old antelope died from rabies 35 days after being bitten on the left hock by a skunk. The result of the direct fluorescent antibody test for rabies was positive.     

DNA microsatellites of pronghorn (Antilocapra americana)

We developed a set of eight polymorphic microsatellite loci for pronghorn, Antilocapra americana. We screened 233 individuals from the National Bison Range in Moiese, MT, and found allele numbers from three to 11 and heterozygosity levels ranging from 0.142 to 0.807. These results suggest that these loci will be useful in paternity analysis and basic population genetics applications.     

Bluetongue in free-ranging pronghorn antelope (Antilocapra americana) in Wyoming: 1976 and 1984

At least 3,200 pronghorn (Antilocapra americana) died during a bluetongue (BT) epizootic in eastern Wyoming during late September and early October 1976. In August and September 1984, another BT epizootic occurred in northeastern Wyoming resulting in 300 known pronghorn deaths. In 17 pronghorn examined postmortem, hemorrhages and edema were the most common gross pathologic changes. Microscopic changes included hemorrhage, edema, arterial fibrinoid necrosis, lymphoid depletion in splenic and lymphatic follicles, and neuronal necrosis. Bluetongue virus serotype 17 was isolated from pronghorn in both epizootics. Mortalities ceased with the advent of cool weather in late September and October. Seventy-six of 94 pronghorn killed by hunters during the latter period of the 1976 epizootic, and 14 of 24 pronghorn killed 1 yr later had serologic evidence of exposure to BT virus. The reproductive rate in pronghorn was depressed to 47 fawns per 100 does in August 1977, but returned to 93 fawns per 100 does by 1978. Following the 1984 outbreak, the reproductive rate was similarly depressed, but the cause was confounded by other environmental and range conditions. Deer, mostly mule deer (Odocoileus hemionus), also died during both epizootics of what was presumed to be BT.     

Thermoregulatory anatomy of pronghorn (Antilocapra americana)

We have found that pronghorn (Antilocapra americana) use external heat exchange with the environment and internal heat exchange between the carotid artery rete and cavernous venous sinus blood to regulate body temperature. Now we have investigated the relationship between the histological structure of the skin, cephalic veins, and carotid rete–cavernous sinus system and the physiological mechanisms pronghorn use, and whether their thermoregulatory anatomy has adaptive advantages. We harvested tissue samples of skin, three veins (i.e., angularis oculi vein, dorsal nasal vein, and facial vein), and the carotid rete–cavernous sinus system from four pronghorn, two culled in summer and two in winter, and examined each histologically. The three veins had the typical structure of veins with large lumina and thin walls. The carotid rete consisted of small (0.1–0.5 mm) arterioles with a density of ~10/mm², intertwined with veins (~2/mm²), enclosed within the cavernous sinus; a structure ideal for heat exchange. We concluded that the main function of the dorsal nasal and facial veins is to return cold blood to the body to effect whole body cooling. The cavernous sinus is supplied with warm blood by the palatine veins in winter and cold blood by the deep facial veins in summer, an arrangement different to that in other ungulates, such as sheep, in which the angularis oculi vein supplies the cavernous sinus. Pronghorn skin is richly supplied with blood vessels that facilitate convective heat loss in summer. In winter, the number of coarse and fine hairs per square millimeter increases more than in European deer to form a thick pelage that minimizes heat loss. In summer, the pelage is shed because hair follicles involute. Unlike in other ungulates, pronghorn skin has little adipose tissue. The number of apocrine glands increases in winter rather than in summer. We concluded that the glands have a reproductive/social function rather than a thermoregulatory one. In summary, our study shows that the thermoregulatory anatomy is consistent with our physiological data and has adaptive advantages that help explain the survival of pronghorn in an arid habitat characterized by extreme temperature variation and sparse vegetation.     

Inbreeding depression in pronghorn (Antilocapra americana) fawns

Although inbreeding depression affects survival, fitness and population viability, the extent of inbreeding depression in wild populations remains unclear. We examined inbreeding depression in the small, isolated National Bison Range (NBR), MT, pronghorn (Antilocapra americana) population following a bottleneck. We have studied the National Bison Range pronghorn extensively since 1981, and we have detailed birth, survival and mate choice data. We genotyped all animals in the population between 1999 and 2010 at 19 microsatellite loci, assigned paternities to all fawns based on genotype and constructed a genetic-based pedigree to calculate inbreeding coefficients (f). We found an increase in the frequency of inbreeding following the bottleneck. We detected evidence of inbreeding depression on fawn survival to weaning, birth mass, foot length and condition. We estimated the number of diploid lethal equivalents on survival to weaning as 24.17-28.72. Standardized heterozygosity (H) had a relatively small influence on survival, mass, length and condition compared with f, and H was not correlated with f. We conclude that for pronghorn, H was not a good predictor of pedigree-estimates of f.     

Invasive entamoebae in pronghorn (Antilocapra americana) from Wyoming

Trophozoites and cysts of an amoeba resembling Entamoeba bovis were recovered from soft stools of captive pronghorn fawns (Antilocapra americana). Chronic or intermittent diarrhea was observed in most individuals in two groups of hand-raised 1- to 8-mo-old pronghorns. Ileocecal lymph nodes were mildly to moderately enlarged. Microscopic lesions were characterized by lymphoid hyperplasia, focal necrosis and pyogranulomatous inflammation in lymph nodes and focal necrosis and diffuse nonsuppurative enteritis in ileum and cecum. In 12 of 17 fawns, trophic stages of amoebae were observed in the submucosa of the cecum and/or the cortex of the ileocecal lymph node. This is the first report of E. bovis-like organisms invading and causing pathological changes in the tissues of their host.     

Phylogeny of ruminants secretory ribonuclease gene sequences of pronghorn (Antilocapra americana)

Phylogenetic analyses based on primary structures of mammalian ribonucleases, indicated that three homologous enzymes (pancreatic, seminal and brain ribonucleases) present in the bovine species are the results of gene duplication events, which occurred in the ancestor of the ruminants after divergence from other artiodactyls. In this paper sequences are presented of genes encoding pancreatic and brain-type ribonuclease genes of pronghorn (Antilocapra americana). The seminal-type ribonuclease gene could not be detected in this species, neither by PCR amplification nor by Southern blot analyses, indicating that it may be deleted completely in this species. Previously we demonstrated of a study of amino acid sequences of pancreatic ribonucleases of a large number of ruminants the monophyly of bovids and cervids, and that pronghorn groups with giraffe. Here we present phylogenetic analyses of nucleotide sequences of ribonucleases and other molecules from ruminant species and compare these with published data. Chevrotain (Tragulus) always groups with the other ruminants as separate taxon from the pecora or true ruminants. Within the pecora the relationships between Bovidae, Cervidae, Giraffidae, and pronghorn (Antilocapra) cannot be decided with certainty, although in the majority of analyses Antilocapra diverges first, separately or joined with giraffe. Broad taxon sampling and investigation of specific sequence features may be as important for reliable conclusions in phylogeny as the lengths of analyzed sequences.     

Serologic survey for pathogens potentially affecting pronghorn (Antilocapra americana) fawn recruitment in Arizona, USA

During the 1990s, pronghorn (Antilocapra americana) populations declined in Arizona, USA. To investigate potential causes of decline, we collected blood samples from hunter-harvested male pronghorn from 2001 to 2003 on four Arizona sites. Sera were tested for antibody to parainfluenza virus type 3 (PI3), bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, bovine respiratory syncytial virus, epizootic hemorrhagic disease virus (EHDV), bluetongue virus (BTV), and Chlamydia psittaci. Antibody against PI3 was found in 33% of the samples, whereas antibody against BTV/EHDV was found in 77%. Antibodies to other pathogens were found at low prevalence rates. Although pronghorn decline in Arizona is probably not directly related to disease, potential reproductive effects of BTV/EHDV and PI3 infection on pronghorn in Arizona merit further study.     

Enzyme-linked immunosorbent assay for efficient detection of antibody to bluetongue virus in pronghorn (Antilocapra americana)

An indirect enzyme-linked immunosorbent assay (ELISA), using cell-associated viral antigen, was developed for detection of antibody to bluetongue virus (BTV) in field-collected pronghorn (Antilocapra americana) sera. To test the applicability of the ELISA to seroepizootiologic studies, pronghorn serum samples from three Wyoming counties (USA) were tested. Bluetongue virus ELISA results were compared to those of the bluetongue immunodiffusion assay. Discrepant serum samples were retested for reaction to either BTV or epizootic hemorrhagic disease virus. The pronghorn BTV ELISA gave rapid, quantitative, objective results and should facilitate testing large numbers of sera for BT diagnostic and seroepizootiologic studies.     

A seroepidemiologic survey of three pronghorn (Antilocapra americana) populations in southeastern Idaho, 1975-1977

Sera from 104 adult and 42 fawn pronghorn antelope (Antilocapra americana) from southeastern Idaho were tested against selected livestock pathogens. The numbers positive/numbers tested (% positive) were as follows: bovine virus diarrhea - adults 2/102 (2), fawns 0/41 (0);; infectious bovine rhinotracheitis - adults 27/101 (27), fawns 9/42 (22); parainfluenza 3 - adults 79/104 (76), fawns 22/42 (52); bovine adenovirus 7 - adults 42/103 (41), fawns 20/48 (48); bovine adenovirus 3 - adults 11/32 (34), fawns 4/14 (23); Anaplasma marginale - adults 1/104 (1), fawns 1/42 (2). There were no reactors to brucellosis, bluetongue, or epizootic hemorrhagic disease; The prevalence of reactors varied considerably for different locations and for different years.     

Polioencephalomalacia-like disease in pronghorns (Antilocapra americana)

A disease resembling thiamine-responsive polioencephalomalacia of domestic ruminants is described in four wild pronghorn from Saskatchewan. One animal was found dead, two were recumbent and unable to rise and the fourth was staggering and ataxic. Lesions were confined to the brain and consisted of brain swelling with herniation, symmetrical hemorrhagic foci in the thalamus and brainstem, and laminar necrosis of cortical neurons. All animals had been eating grain prior to their death. Possible pathogenetic mechanisms including changes in rumen microflora resulting in thiamine deficiency, plant and salt intoxication are discussed.     

A summary of the prevalence of Parelaphostrongylus tenuis in a captive wapiti population.

A total of 87 brains from harvested and collected wapiti and red deer (Cervus spp.) were examined grossly and microscopically between 1973 and 1977 in a 2104 ha. preserve. Prevalence of infection significantly increased from 26.6% of the sample in 1973 to 64.3% in 1975 (P less than .05). A decline to 47.7% in 1977 (P greater than .05) was not significant. However, the number of clinical cases was significantly higher in 1976-1977 (P less than .02) than previously reported in 1973-1975.     

Distribution of meningeal worm (Parelaphostrongylus tenuis) in South Dakota

Heads of hunter-harvested deer (Odocoileus sp.) and elk (Cervus elaphus) were collected from meat processing plants throughout South Dakota (USA) from 1997 through 1999 to determine distribution of meningeal worm (Parelaphostrongylus tenuis) in eastern and western South Dakota. A total of 2,848 white-tailed deer (WTD) were examined for P. tenuis, of which 578 (20.3%) were infected with the parasite. Of 578 deer infected, 570 (98.6%) were harvested east of the Missouri River. Our results indicate that P. tenuis is widely distributed throughout eastern South Dakota and limited to the southcentral region of western South Dakota. Infected WTD were documented in 37 of 44 counties in eastern South Dakota and three of 22 counties in western South Dakota. No meningeal worms were found on the meninges or cranial surfaces of 215 mule deer ( Odocoileus hemionus) or 344 elk examined. These findings further define the distribution of the parasite throughout the state. We suggest that the Missouri River acts, in part, as a physical barrier to the westward expansion of P. tenuis to the grasslands of western South Dakota.