Diseases and mortality in free-ranging brown bear (Ursus arctos), gray wolf (Canis lupus), and wolverine (Gulo gulo) in Sweden

Ninety-eight brown bears (Ursus arctos), 20 gray wolves (Canis lupus), and 27 wolverines (Gulo gulo), all free-ranging, were submitted to the National Veterinary Institute, Uppsala, Sweden, during 1987-2001 for investigation of diseases and causes of mortality. The most common cause of natural death in brown bears was infanticide. Infanticide also was observed in wolverines but not in wolves. Traumatic injuries, originating from road or railway accidents, were the most common cause of death in wolves and occurred occasionally in brown bears. Most wolverines were submitted as forensic cases in which illegal hunting/poaching was suspected. Sarcoptic mange was observed in several wolves but not in brown bears or wolverines. Sarcoptic mange most likely was acquired from infected red foxes (Vulpes vulpes) that were killed by wolves. Other parasites and infectious diseases were only found sporadically.     

Molecular identification of Taenia spp. in wolves (Canis lupus), brown bears (Ursus arctos) and cervids from North Europe and Alaska

Taenia tapeworms of Finnish and Swedish wolves (Canis lupus) and Finnish brown bears (Ursus arctos), and muscle cysticerci of Svalbard reindeer (Rangifer tarandus platyrhynchus), Alaskan Grant's caribou (Rangifer tarandus granti) and Alaskan moose (Alces americanus) were identified on the basis of the nucleotide sequence of a 396 bp region of the mitochondrial cytochrome c oxidase subunit 1 gene. Two species were found from wolves: Taenia hydatigena and Taenia krabbei. The cysticerci of reindeer, caribou and one moose also represented T. krabbei. Most of the cysticercal specimens from Alaskan moose, however, belonged to an unknown T. krabbei-like species, which had been reported previously from Eurasian elks (Alces alces) from Finland. Strobilate stages from two bears belonged to this species as well. The present results suggest that this novel Taenia sp. has a Holarctic distribution and uses Alces spp. as intermediate and ursids as final hosts.     

Geographic pattern of serum antibody prevalence for Brucella spp. in caribou, grizzly bears, and wolves from Alaska, 1975-1998

Blood samples were collected from 2,635 caribou (Rangifer tarandus), 1,238 grizzly bears (Ursus arctos), and 930 wolves (Canis lupus) from throughout mainland Alaska during 1975-98. Sera were tested for evidence of exposure to Brucella spp. Serum antibody prevalences were highest in the northwestern region of the state. In any specific area, antibody prevalences for caribou and wolves were of a similar magnitude, whereas antibody prevalence for bears in these same areas were two to three times higher.     

Prevalence of Sarcocystis in wolves and white-tailed deer in Northeastern Minnesota

The prevalence of Sarcocystis (Protozoa: Sarcocystidae) in white-tailed deer (Odocoileus virginianus) from northeastern Minnesota was determined by histologic examination of tongue samples. Seventy-nine of 100 deer were infected; infection was higher in yearlings and adults than in fawns. Sporocysts of Sarcocystis were found in 3% of 72 wolf (Canis lupus) scats. Three of four captive wolves fed muscle from a white-tailed deer naturally infected with Sarcocystis shed sporocysts 12-14 days later.     

Sequence analysis of three pigmentation genes in the Newfoundland population of Canis latrans links the Golden Retriever Mc1r variant to white coat color in coyotes

Three genes, Mc1r, Agouti, and CBD103, interact in a type-switching process that controls much of the pigmentation variation observed in mammals. A deletion in the CBD103 gene is responsible for dominant black color in dogs, while the white-phased black bear (“spirit bear”) of British Columbia, Canada, is the lightest documented color variant caused by a mutation in Mc1r. Rare all-white animals have recently been discovered in a new northeastern population of the coyote in insular Newfoundland and Labrador, Canada. To investigate the causative gene and mutation of white coat in coyotes, we sequenced the three type-switching genes in white and dark-phased animals from Newfoundland. The only sequence variants unambiguously associated with white color were in Mc1r, and one of these variants causes the amino acid variant R306Ter, a premature stop codon also linked to coat color in Golden Retrievers and other dogs with yellow/red coats. The allele carrying R306Ter in coyotes matches that in the Golden Retriever at other variable amino acid sites and hence may have originated in these dogs. Coyotes experienced introgression with wolves and dogs as they colonized northeastern North America, and coyote/Golden Retriever interactions have been observed in Newfoundland. We speculate that natural selection, with or without a founder effect, may contribute to the observed frequency of white coyotes in Newfoundland, as it has contributed to the high frequency of white bears, and of a domestic dog-derived CBD allele in gray wolves.     

Characterization of 59 canine single nucleotide polymorphisms in the Italian wolf (Canis lupus) population

We characterized 59 canine single nucleotide polymorphisms (SNPs) in the endangered Italian wolf (Canis lupus) population, which were discovered by resequencing sequence‐tagged‐site (STS) DNA sequences that are known to contain SNPs in domestic dogs. Dog SNPs were usually found also in wolves. Additional SNPs unique in dogs or wolves were discovered, which is important for detecting hybrids between dogs and wolves. We developed new primer sets and analysed 15 SNPs by Pyrosequencing. The characterized SNPs will provide an important addition to the genetic markers that are currently available for studying wild populations of canids.     

Sarcocystis caninum and Sarcocystis svanai n. spp. (Apicomplexa: Sarcocystidae) Associated with Severe Myositis and Hepatitis in the Domestic Dog (Canis familiaris)

There are several reports of Sarcocystis sarcocysts in muscles of dogs, but these species have not been named. Additionally, there are two reports of Sarcocystis neurona in dogs. Here, we propose two new names, Sarcocystis caninum, and Sarcocystis svanai for sarcocysts associated with clinical muscular sarcocystosis in four domestic dogs (Canis familiaris), one each from Montana and Colorado in the USA, and two from British Columbia, Canada. Only the sarcocyst stage was identified. Most of the sarcocysts identified were S. caninum. Sarcocysts were studied using light microscopy, transmission electron microscopy (TEM), and polymerase chain reaction. Based on collective results two new species, S. caninum and S. svanai were designated. Sarcocystis caninum and S. svanai were structurally distinct. Sarcocystis caninum sarcocysts were up to 1.2 mm long and up to 75 μm wide. By light microscopy, the sarcocyst wall was relatively thin and smooth. By TEM, the sarcocyst wall was “type 9”, 1–2 μm thick, and contained villar protrusions that lacked microtubules. Bradyzoites in sections were 7–9 μm long. Sarcocysts of S. svanai were few and were identified by TEM. Sarcocystis svanai sarcocysts were “type 1”, thin walled (< 0.5 μm), and the wall lacked villar protrusions but had tiny blebs that did not invaginate. DNA was extracted either from infected frozen muscle biopsies or formalin‐fixed paraffin‐embedded sections. Dogs were either singly infected with S. caninum or multiply co‐infected with S. caninum and S. svanai (the result of a mixed infection) based on multilocus DNA sequencing and morphology. BLASTn analysis established that the sarcocysts identified in these dogs were similar to, but not identical to Sarcocystis canis or Sarcocystis arctosi, parasites found to infect polar bears (Ursus maritimus) or brown bears (Ursus arctosi), respectively. However, the S. caninum sequence showed 100% identify over the 18S rRNA region sequenced to that of S. arctica, a parasite known to infect Arctic foxes (Vulpes lagopus).     

Sarcocystis of deer in South Dakota

The prevalence of Sarcocystis in white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) in South Dakota was determined through microscopic examination of tongue samples. The percentage of Sarcocystis infection for both species of deer was determined for prairies east of the Missouri River, west of the Missouri River, and Black Hills of western South Dakota. Sixteen percent (N = 62) of the white-tailed deer tongues from East River, 69% (N = 42) from West River, and 74% (N = 23) from the Black Hills were infected. Prevalence for mule deer was 88% (N = 24), 78% (N = 63), and 75% (N = 12) from East River, West River, and the Black Hills, respectively. Of 50 tongue samples obtained from both species of deer during a special antlerless deer hunt in the Black Hills in 1978, 66% were infected. Coyotes (Canis latrans), dogs (Canis familiaris), red foxes (Vulpes vulpes), a gray fox (Urocyon cinereoargenteus), bobcat (Felis rufus), and raccoon (Procyon lotor) were fed muscle from white-tailed deer and mule deer naturally infected with Sarcocystis to determine their role as definitive hosts. All coyotes, dogs, and the gray fox shed sporocysts, while none were recovered from the other animals. Sporocysts shed by coyotes were counted and concentrated into an inoculum and administered to a white-tailed deer fawn, which was necropsied 85 days after inoculation. Sections of heart, tongue, esophagus, diaphragm, and skeletal muscle were found to be heavily infected with sarcocysts, while sarcocysts were not detected in a control fawn.     

Size‐assortative choice and mate availability influences hybridization between red wolves (Canis rufus) and coyotes (Canis latrans)

Anthropogenic hybridization of historically isolated taxa has become a primary conservation challenge for many imperiled species. Indeed, hybridization between red wolves (Canis rufus) and coyotes (Canis latrans) poses a significant challenge to red wolf recovery. We considered seven hypotheses to assess factors influencing hybridization between red wolves and coyotes via pair‐bonding between the two species. Because long‐term monogamy and defense of all‐purpose territories are core characteristics of both species, mate choice has long‐term consequences. Therefore, red wolves may choose similar‐sized mates to acquire partners that behave similarly to themselves in the use of space and diet. We observed multiple factors influencing breeding pair formation by red wolves and found that most wolves paired with similar‐sized conspecifics and wolves that formed congeneric pairs with nonwolves (coyotes and hybrids) were mostly female wolves, the smaller of the two sexes. Additionally, we observed that lower red wolf abundance relative to nonwolves and the absence of helpers increased the probability that wolves consorted with nonwolves. However, successful pairings between red wolves and nonwolves were associated with wolves that maintained small home ranges. Behaviors associated with territoriality are energetically demanding and behaviors (e.g., aggressive interactions, foraging, and space use) involved in maintaining territories are influenced by body size. Consequently, we propose the hypothesis that size disparities between consorting red wolves and coyotes influence positive assortative mating and may represent a reproductive barrier between the two species. We offer that it may be possible to maintain wild populations of red wolves in the presence of coyotes if management strategies increase red wolf abundance on the landscape by mitigating key threats, such as human‐caused mortality and hybridization with coyotes. Increasing red wolf abundance would likely restore selection pressures that increase mean body and home‐range sizes of red wolves and decrease hybridization rates via reduced occurrence of congeneric pairs.     

First report of Thelazia callipaeda (Spirurida, Thelaziidae) in wolves in Italy

Thelazia callipaeda (Spirurida, Thelaziidae) infects the eyes of humans and rabbits as well of domestic and wild carnivores (i.e., dogs, cats, and foxes). The first three cases of infection by T. callipaeda eyeworms in wolves (Canis lupus) are here described with up to 96 nematodes collected from a single animal. The host competence of wolf was demonstrated by the retrieval of adult worms in the eyes of all examined animals. All nematodes collected were evaluated by morphologic and molecular techniques. Sequence analysis of the partial mitochondrial cytochrome c oxidase subunit 1 gene (cox1) confirmed that only one haplotype of T. callipaeda was present. The competence of wolves as a definitive host for T. callipaeda is discussed in view of the relevance of wild fauna in maintaining and spreading eyeworm infection in humans and domestic animals.     

Pedigree-based assignment tests for reversing coyote (Canis latrans) introgression into the wild red wolf (Canis rufus) population

The principal threat to the persistence of the endangered red wolf (Canis rufus) in the wild is hybridization with the coyote (Canis latrans). To facilitate idengification and removal of hybrids, assignment tests are developed which use genotype data to estimate identity as coyote, 1/4, 1/2, 3/4 or full red wolf. The tests use genotypes from the red wolves that founded the surviving population and the resulting pedigree, rather than a contemporary red wolf sample. The tests are evaluated by analysing both captive red wolves at 18 microsatellite loci, and data simulated under a highly parameterized, biologically reasonable model. The accuracy of assignment rates are generally high, with over 95% of known red wolves idengified correctly. There are, however, tradeoffs between ambiguous assignments and misassignments, and between misidengifying red wolves as hybrids and hybrids as red wolves. These result in a compromise between limiting introgression and avoiding demographic losses. The management priorities and level of introgression determine the combination of test and removal strategy that best balances these tradeoffs. Ultimately, we conclude that the use of the assignment tests has the capacity to arrest and reverse introgression. To our knowledge, the presented approach is novel in that it accounts for genetic drift when the genotypes under analysis are temporally separated from the reference populations to which they are being assigned. These methods may be valuable in cases where reference databases for small populations have aged substantially, pedigree information is available or data are generated from historical samples.     

Polymorphism of alpha 1-antitrypsin in North American species of Canis

alpha 1-Antitrypsin (A1AT) is a major protease inhibitor present in all mammalian sera that have thus far been investigated. A1AT is also highly polymorphic and is therefore a useful genetic marker. Previously reported A1AT polymorphism in domestic dogs consisted of two alleles designated as PiM and PiS which exhibited frequencies of 0.72 and 0.28, respectively, in a group of randomly collected mongrel dogs. North American species of Canis, which included gray wolves (n = 29), Mexican wolves (n = 20), coyotes (n = 24), wolf-dog crosses (n = 9), and red wolves (n = 27) were tested for A1AT polymorphism. A1AT phenotypes were determined by isoelectric focusing, followed by direct immunoblotting using a specific antiserum. A1AT concentrations were determined by radial immunodiffusion. Concentrations of A1AT were similar to those found in domestic dogs (2.26 +/- 0.3, +/- SD mg/ml, +/- SD) and tended to be higher in females than in males, possibly indicating that A1AT may be hormonally influenced in females. Three phenotypic band patterns were observed (M, MS, S). The allele frequencies for domestic dogs and gray wolves were very similar, 0.72 and 0.67 for PiM and 0.28 and 0.33 for PiS, respectively. The Mexican wolves had a significantly lower frequency of PiS = 0.10. Coyotes and red wolves were all found to be monomorphic for the PiS allele and were indistinguishable from each other in that respect.     

Parelaphostrongylus odocoilei (Nematoda: Protostrongylidae) and a protostrongylid nematode in woodland caribou (Rangifer tarandus caribou) of Alberta, Canada

Two size-groups of dorsal-spined, first-stage, nematode larvae were found in feces of woodland caribou, Rangifer tarandus caribou (Gmelin), in Alberta from 1976-1982. Larvae from caribou feces in northeastern Alberta were 451 +/- 17 micrograms in length, while those from west-central Alberta were 362 +/- 18 micrograms in length. Larvae collected from west-central Alberta developed to the infective stage, experimentally, in the terrestrial gastropod Triodopsis multilineata (Say) and were infective to captive mule deer fawns, Odocoileus H. hemionus (Rafinesque). Adult nematodes, identified as Parelaphostrongylus odocoilei (Hobmaier and Hobmaier, 1934), were recovered from the skeletal muscles of the mule deer.     

Detection of Echinococcus granulosus coproantigens in Australian canids with natural or experimental infection

Coproparasitological and purging methods for diagnosing canids infected with the intestinal helminth Echinococcus granulosus, an important zoonotic parasite, are unreliable. Detection of coproantigens in feces of infected dogs by enzyme-linked immunosorbent assay (ELISA) is suitable for detecting patent and prepatent infections with a high degree of sensitivity and specificity. In the present study, natural and experimental infections in domestic and wild Australian canids were investigated using a coproantigen capture ELISA. Experimental infection of dogs with E. granulosus was detected at between 14 and 22 days postinfection (PI), and optical density (OD) values remained high until termination of experiments 35 days PI. After chemotherapy, coproantigen levels in infected dogs dropped rapidly, becoming negative 2-4 days after treatment. In experimentally infected red foxes (Vulpes vulpes), the coproantigen excretion profile was different, with ELISA OD levels peaking 15-17 days PI, then falling to low or undetectable levels by 30 days PI. Coproantigens were detected in the feces of naturally infected Australian wild dogs (dingoes, dingo/domestic dog hybrids) with infection levels ranging between 2 worms and 42,600. Preliminary data on the stability of coproantigen in dog feces exposed to environmental conditions indicated that there was no change in antigenicity over 6 days. The results suggest the coproantigen ELISA could be successfully used to monitor E. granulosus prevalence rates in Australian domestic dogs, foxes, and wild dogs.     

Serologic survey for Toxoplasma gondii in selected wildlife species from Alaska

Blood was collected from selected wildlife species in specific areas of Alaska (USA) during 1976-96. A modified agglutination test was used to test sera for evidence of exposure to Toxoplasma gondii. Serum antibody prevalence was 43% (62 positive of 143 tested) for black bears (Ursus americanus), 9% (11/125) for wolves (Canis lupus), 7% (22/319) for Dall sheep (Ovis dalli), 6% (14/241) for caribou (Rangifer tarandus), 1% (3/240) for moose (Alces alces), and 1% (2/241) for bison (Bison bison). A predictive model was developed to determine the effect of sex, age, location, and year of collection on antibody prevalence for each species. Prevalence was higher in older black bears, caribou, and wolves. For black bears, prevalence was highest in the southeast region of the state. For caribou, prevalence was lowest on the Alaska Peninsula.     

Wolves,white‐tailed deer,and beaver: implications of seasonal prey switching for woodland caribou declines

Population increases of primary prey can negatively impact alternate prey populations via demographic and behavioural responses of a shared predator through apparent competition. Seasonal variation in prey selection patterns by predators also can affect secondary and incidental prey by reducing spatial separation. Global warming and landscape changes in Alberta's bitumen sands have resulted in prey enrichment, which is changing the large mammal predator–prey system and causing declines in woodland caribou Rangifer tarandus caribou populations. We assessed seasonal patterns of prey use and spatial selection by wolves Canis lupus in two woodland caribou ranges in northeastern Alberta, Canada, that have undergone prey enrichment following recent white‐tailed deer Odocoileus virginianus invasion. We determined whether risk of predation for caribou (incidental prey) and the proportion of wolf‐caused‐caribou mortalities varied with season. We found that wolves showed seasonal variation in primary prey use, with deer and beaver Castor canadensis being the most common prey items in wolf diet in winter and summer, respectively. These seasonal dietary patterns were reflected in seasonal wolf spatial resource selection and resulted in contrasting spatial relationships between wolves and caribou. During winter, wolf selection for areas used by deer maintained strong spatial separation between wolves and caribou, whereas wolf selection for areas used by beaver in summer increased the overlap with caribou. Changing patterns in wolf resource selection were reflected by caribou mortality patterns, with 76.2% of 42 adult female caribou mortalities occurring in summer. Understanding seasonal patterns of predation following prey enrichment in a multiprey system is essential when assessing the effect of predation on an incidental prey species. Our results support the conclusion that wolves are proximately responsible for woodland caribou population declines throughout much of their range.     

Rabies of wild mammals in Russia at the turn of the 20th and 21st centuries

Analysis of the incidence of animal rabies in Russia (1960–2006) and assessment of the abundance of wild canids and rabies infection prevalence among them (1981–2006) have been made. The results provide evidence for the dominant role of red foxes in the spread of rabies among wild animals (91.67%), which is confirmed by a strong correlation between the abundance of this predator and the numbers of infected animals (r = 0.73). In 2004 to 2006, the prevailing incidence of animal rabies in one or another territory was determined mainly (74.7%) by the pooled population density of red and corsac foxes and wolves. Natural and economic features of the landscape determined the incidence of rabies indirectly, via changes in the numbers of wild animals (by 68.9%). A comparative analysis of the recorded and potentially possible rabies incidence rates among wolves, red and corsac foxes, and raccoon dogs over the period from 1996 and 2006 is presented.     

Prevalence and distribution of Sarcocystis spp. among white-tailed deer of the southeastern United States

Sarcocysts were found by light microscopic examination of muscle in 199 (51%) of 390 white-tailed deer (Odocoileus virginianus) from the southeastern United States. Sarcocystis infections were detected more frequently in histologic sections of tongue (45%) than of heart (9%). Sarcocysts were significantly more prevalent in adult deer (54%) than fawns (26%) (P less than .01). Statistically significant differences in prevalence were not found in deer from different physiographic provinces or between sexes. Artificial digestion was more sensitive in detecting Sarcocystis infections than examination of histologic sections when both techniques were used to examine tongues of 35 deer. Three different size sporocysts, possibly representing at least two species of Sarcocystis, were recovered during feeding trials. Seven dogs (Canis familiaris) shed sporocysts 9 to 12 days after eating infected venison. Sporocysts measured 13.4-16.8 x 9.0-12.3 micrometers with an average measurement of 15.2 x 10.9 micrometers (N = 195). One of three cats (Felis catus) and one of two red foxes (Vulpes vulpes) first shed sporocysts of Sarcocystis 10 days after eating infected venison. Sporocysts from the cat measured 11.2-13.4 x 6.72-8.96 micrometers (avg 12.0 x 8.7 micrometers, N = 18), and those from the fox measured 11.2-15.7 x 9.0-11.2 micrometers (avg 13.6 x 10.2 micrometers, N = 7).     

Experimental infections of Sarcocystis cruzi, Sarcocystis tenella, Sarcocystis capracanis and Toxoplasma gondii in red foxes (Vulpes vulpes)

Four littermate 6-wk-old red foxes (Nos. 1-4) were fed Toxoplasma gondii, Sarcocystis cruzi, S. tenella and S. capracanis. One littermate fox (No. 5) served as the control. Two foxes (Nos. 1, 2) were fed tissue cysts of T. gondii and two foxes (Nos. 3, 4) were fed oocysts of T. gondii. Twenty-one to 42 days later, the same five foxes were used to test the infectivity of meat of goat, sheep, and ox experimentally inoculated with Sarcocystis. Fox 2 was fed goat meat and shed S. capracanis-like sporocysts 10 days later. Foxes 3 and 4 were fed beef, and they shed S. cruzi-like sporocysts 9 days later. Fox 5 was fed sheep meat and shed S. tenella-like sporocysts 8 days later. Foxes were killed between 36 and 55 days of the experiment and their tissues were inoculated into mice to recover T. gondii. All foxes remained clinically normal and T. gondii was recovered from all inoculated foxes and not from the control. Sarcocystis sporocysts from foxes induced lethal infections in goats, sheep, and ox. The sporocysts, meronts, merozoites, and sarcocysts of fox-derived parasites were similar to those derived from coyotes or dogs. It was concluded that the red fox can act as a final host for the three pathogenic species of Sarcocystis in cattle, sheep, and goats.     

Mitochondrial DNA restriction-fragment-length monomorphism in the Italian wolf (Canis lupus) population

Mitochondrial-DNA (mtDNA) restriction patterns were studied in 22 wolves (Canis lupus) sampled in central-northern Italy. A total of 60 restriction sites were detected, encompassing about 2 % of the mitochondrial genome of canids. All wolves showed the same restriction pattern. Therefore, a single mtDNA haplotype was detected in the Italian wolf population. Historical information on peninsular isolation and demographic decline suggest that low genetically effective population size and random drift may have strongly reduced the mtDNA variability of wolves in Italy over the last 100–200 years. A different mtDNA restriction pattern in feral dogs sampled from a wolf range in central Italy was detected. These findings suggest that the hybridization and introgression of female dog genomes into the Italian wolf population may be rare or absent.