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PubMed2003

Concentrations of selected essential and non-essential elements in arctic fox (Alopex lagopus) and wolverines (Gulo gulo) from the Canadian Arctic.

Arctic fox (Alopex lagopus) and wolverine (Gulo gulo) tissues were collected in the Canadian Arctic from 1998 to 2001 and analyzed for various essential and non-essential elements. Several elements (Ag, Al, As, B, Ba, Be, Co, Cr, Mo, Ni, Sb, Sn, Sr, Tl, U and V) were near or below the detection limits in >95% arctic fox and wolverine samples. Concentrations of Cd, Cu, Fe, total Hg (THg), Mn, Pb, Se and Zn were quantifiable in >50% of the samples analyzed and reported herein. Hepatic elemental concentrations were not significantly different among arctic foxes collected at Ulukhaqtuuq (Holman), NT (n=13) and Arviat, NU (n=50), but were significantly greater than concentrations found in wolverine liver from Kugluktuk (Coppermine), NU (n=12). The mean (+/-1 S.E.) concentrations of Cd in kidney were also significantly greater in arctic fox (1.08+/-0.19 microg g(-1) wet wt.) than wolverine (0.67+/-0.18 microg g(-1) wet wt.). However, mean hepatic Cu concentrations (Ulukhaqtuuq: 5.5+/-0.64; Arviat: 7.1+/-0.49 microg g(-1) wet wt.) in arctic foxes were significantly lower than in wolverines (32+/-3.3 microg g(-1) wet wt.). Hepatic total Hg (THg) concentrations in arctic fox from this study were not significantly different from specimens collected in 1973, suggesting that THg concentrations have not changed dramatically over the past 30 years. The mono-methylmercury (MeHg) concentrations in selected (n=10) arctic fox liver samples from Arviat (0.14+/-0.07 microg g(-1) wet wt.) comprised 14% of THg. While the molar concentrations of THg were correlated with Se in arctic foxes and wolverines, the hepatic Hg/Se molar ratios were consistently lower than unity; suggesting that Se-mediated detoxification pathways of Hg are not overwhelmed at current exposure.

Animals↗

PubMed2003

Organochlorine contaminant and stable isotope profiles in Arctic fox (Alopex lagopus) from the Alaskan and Canadian Arctic.

Arctic fox (Alopex lagopus) is a circumpolar species distributed across northern Canada and Alaska. Arctic fox muscle and liver were collected at Barrow, AK, USA (n=18), Holman, NT, Canada (n=20), and Arviat, NU, Canada (n=20) to elucidate the feeding ecology of this species and relate these findings to body residue patterns of organochlorine contaminants (OCs). Stable carbon (delta 13C) and nitrogen (delta 15N) isotope analyses of Arctic fox muscle indicated that trophic position (estimated by delta 15N) is positively correlated with increasing delta 13C values, suggesting that Arctic fox with a predominantly marine-based foraging strategy occupy a higher trophic level than individuals mostly feeding from a terrestrial-based carbon source. At all sites, the rank order for OC groups in muscle was polychlorinated biphenyls (Sigma PCB) > chlordane-related compounds (Sigma CHLOR) > hexachlorocyclohexane (Sigma HCH) > total toxaphene (TOX) > or = chlorobenzenes (Sigma ClBz) > DDT-related isomers (Sigma DDT). In liver, Sigma CHLOR was the most abundant OC group, followed by Sigma PCB > TOX > Sigma HCH > Sigma ClBz > Sigma DDT. The most abundant OC analytes detected from Arctic fox muscle and liver were oxychlordane, PCB-153, and PCB-180. The comparison of delta 15N with OC concentrations indicated that relative trophic position might not accurately predict OC bioaccumulation in Arctic fox. The bioaccumulation pattern of OCs in the Arctic fox is similar to the polar bear. While Sigma PCB concentrations were highly variable, concentrations in the Arctic fox were generally below those associated with the toxicological endpoints for adverse effects on mammalian reproduction. Further research is required to properly elucidate the potential health impacts to this species from exposure to OCs.

Alaska↗

PubMed2000

Screening for infection of Trichinella in red fox (Vulpes vulpes) in Denmark.

A total of 6141 foxes (Vulpes vulpes) were examined for infection with Trichinella. The foxes were killed in Denmark during the hunting season 1995-1996 and 1997-1998; 3133 and 3008, respectively. Foxes included in the investigation came from throughout the country with the exception of the island of Bornholm. The right foreleg from each fox was submitted for investigation. The legs were stored at -20 degrees C for 3-10 months prior to examination. Following thawing, muscle tissue (10 g) from each leg was examined by trichinoscopy and by a pepsin-HCl digestion technique. In 1995-1996, three foxes were found positive corresponding to a prevalence of 0.001. Each of the infected foxes harboured an extremely low infection, i.e. about one larva per 10 g muscle tissue. It was not possible to obtain sufficient larval material for species identification. All three foxes were shot in the vicinity of a small village in the north-western part of Denmark. In 1997-1998 no Trichinella cases were found. The results, compared with previous studies, indicate that the prevalence of infection of Trichinella sp. among wild living foxes in Denmark is very low. This is further supported by the fact, that no infection of Trichinella sp. has been found in slaughtered pigs in Denmark for more than 65 years, which suggests that the infection pressure is very low. Considering the facts above we conclude that the risk of Trichinella infections is negligible in intensive indoor pig production units in Denmark whereas high local prevalence of Trichinella infections in the wildlife might constitute a serious risk for the expanding outdoor pig production.

Animals↗

PubMed1993

Epidemiology of Toxocara canis in red foxes (Vulpes vulpes) from urban areas of Bristol.

A descriptive epidemiological survey was undertaken of the ascarid nematode Toxocara canis in 521 red foxes (Vulpes vulpes) during the period January 1986 to July 1990. Age-prevalence and age-intensity profiles show that worm burdens are significantly higher in cubs than in subadult or adult foxes and higher in subadult than in adult foxes. Seasonal variations in worm burdens occur, with the highest prevalences and intensities being found during the spring, when cubs are born, and in the summer months. Prevalences and intensities then decrease during the autumn and winter months in both subadult and adult foxes, but, during this period, prevalences are significantly higher in male than in female foxes. Variations in worm burdens in the fox population are likely to be related to the reproductive cycle of the fox, with a high proportion of cubs becoming infected in utero. The role of the fox in the transmission of T. canis in the urban environment is discussed.

Age Factors↗

PubMed2000

Preliminary study of the role of red foxes in Echinococcus multilocularis transmission in the urban area of Sapporo, Japan.

In order to assess the infection risk of alveolar echinococcosis among urban residents of Sapporo, the capital of Hokkaido, Japan, a survey was conducted on fox distribution in the urban area and on the prevalence of Echinococcus multilocularis among the foxes. The fox distribution, evaluated from fox footprints left on the snow in parks and woodlands, and from locations of fox carcasses recorded by the Sapporo municipality, was concentrated along the border of the urban area and in the southwestern part of the city, facing the mountain. Fox faeces were collected around active fox dens, and analysed by a coproantigen detection assay and parasite egg examination for the Echinococcus infection. Thirty-three out of 155 faeces were coproantigen positive. Coproantigen-positive faeces were collected from 11 den sites (57.9% of total den sites), and all except 1 were located in the urban fringe. A high intensity of taeniid eggs (> 100 eggs per 0.5 g) containing faeces were also collected in the 3 sites of them. Although Echinococcus infection in rodents was not observed from the necropsy of 23 rodents captured around active fox dens, arvicolid rodents, a suitable intermediate host for E. multilocularis, were captured in the urban fringe. Therefore, the urban fringe offers suitable conditions in which the life-cycle of E. multilocularis could be maintained. Prompt measures to control echinococcus infection should be taken, even in urban areas.

Animals↗

PubMed2003

The city-fox phenomenon: genetic consequences of a recent colonization of urban habitat.

The red fox (Vulpes vulpes) is one of the best-documented examples of a species that has successfully occupied cities and their suburbs during the last century. The city of Zurich (Switzerland) was colonized by red foxes 15 years ago and the number of recorded individuals has increased steadily since then. Here, we assessed the hypothesis that the fox population within the city of Zurich is isolated from adjacent rural fox populations against the alternative hypothesis that urban habitat acts as a constant sink for rural dispersers. We examined 11 microsatellite loci in 128 foxes from two urban areas, separated by the main river crossing the city, and three adjacent rural areas from the region of Zurich. Mean observed heterozygosity across individuals and the number of detected alleles were lower for foxes collected within the city as compared with their rural conspecifics. Genetic differentiation was significantly lower between rural than between rural and urban populations, and highest value of pairwise FST was recorded between the two urban areas. Our results indicate that the two urban areas were independently founded by a small number of individuals from adjacent rural areas resulting in genetic drift and genetic differentiation between rural and urban fox populations. Population admixture and immigration analysis revealed that urban-rural gene flow was higher than expected from FST statistics. In the five to seven generations since colonization, fox density has dramatically increased. Currently observed levels of migration between urban and rural populations will probably erode genetic differentiation over time.

Alleles↗

PubMed2004

Rabies in red foxes (Vulpes vulpes) experimentally infected with European bat lyssavirus type 1.

The susceptibility of red foxes (Vulpes vulpes) to European bat lyssavirus type 1 (EBLV-1) infection was examined. Eight foxes were inoculated intramuscularly (i.m.) with 10(4.9) foci-forming units (FFU) (n = 4) and 10(5.1) FFU (n = 4) and observed for up to 90 days. All foxes showed manifestations of a neurologic disorder (e.g. seizures, myoclonus, agitation), starting as early as 5 days post-infection (p.i.). Subsequently, all animals showed improvement followed by one or more relapses. One fox was killed 3 days after it recovered, 26 days post-infection. Two other foxes were also killed 38 and 54 days post-infection after severe neurologic signs returned. All foxes developed a humoral immune response against EBLV-1 as determined in serum and brain tissues. However, no rabies virus antigen was detected in the brain, other tissues and secretions examined (e.g. salivary gland, saliva, tonsils, lungs) by using different standard diagnostic techniques [fluorescent antibody test, reverse transcription polymerase chain reaction (RT-PCR), rabies tissue culture inoculation test], with the exception of one fox in which EBLV-1 RNA was detected by RT-PCR in only the spinal cord. Brain tissues showed moderate to severe multifocal, mononuclear encephalomyelitis in the three foxes that were killed during the observation period, although no EBLV-1 virus was detectable in these tissues.

Animals↗

PubMed1989

Three new plasma protein polymorphisms in domestic foxes, detected by a simple method of 2D horizontal electrophoresis.

Plasma samples of 270 foxes from 45 complete families (14 of arctic foxes, 28 of silver foxes and 3 with arctic x silver fox hybrid offspring) were analysed by a method of two-dimensional agarose gel (pH 5.4)-horizontal polyacrylamide gel (pH 9.0) electrophoresis followed by general-protein staining of gels. Genetic polymorphism of three plasma proteins, tentatively designated prealbumin (Pr), postalbumin 1 (Pa1), and pretransferin 1 (Prt1), was observed. In silver foxes, Pa1 and Prt1 showed a high degree of polymorphism, each with 3 common alleles, while Pr showed a scarce polymorphism. The arctic foxes were monomorphic for Pr and Prt1 and showed a scarce Pa1 polymorphism. The Prt1 phenotype of arctic foxes showed identical mobility with one of the Prt1 variants of silver foxes.

Animals↗

PubMedDate not supplied

Assessment of antibodies to rabbit haemorrhagic disease virus in fox serum as an indicator of infection in sympatric rabbit populations.

OBJECTIVE: To assess the value of foxes as indicators of rabbit haemorrhagic disease virus in sympatric populations of rabbits. DESIGN: Serum samples from 341 foxes in central western New South Wales were tested for exposure to rabbit haemorrhagic disease virus using antibody cELISAs. Selected samples were tested for viral antigens by ELISA, viral nucleic acids by reverse transcriptase PCR and viral infectivity by rabbit inoculation. RESULTS: Antibodies against rabbit haemorrhagic disease virus were first detected in foxes 4 months after rabbit haemorrhagic disease was observed in rabbits in the same area. There was evidence of exposure of foxes to the virus in two subsequent years. A proportion of antibody positive, inconclusive and negative serum samples from foxes gave false positive results in an antigen ELISA for rabbit haemorrhagic disease virus. These serum samples were negative for viral nucleic acid by reverse transcriptase PCR and for infectious virus by rabbit inoculation. Liver samples from foxes were negative for viral antigens. CONCLUSIONS: Antibodies against rabbit haemorrhagic disease virus in fox serum can serve as an index of the occurrence of rabbit haemorrhagic disease in rabbit populations. Some fox serum samples exhibit false positive reactivity in an antigen ELISA for rabbit viral haemorrhagic disease virus.

Animals↗

PubMed1994

Efficacy of the first oral vaccination against fox rabies in Slovenia.

Fox population reduction was the first measure undertaken to control rabies in foxes, but this proved unsuccessful. The promising results of oral immunisation of foxes against rabies in some European countries encouraged the authorization of the first rabies vaccination of foxes in the field in Slovenia, in October 1988. In the present study, intervention analysis is used to evaluate the results of this vaccination campaign. The analysis took into account the cyclic nature of fox rabies and the possible effects of variability in the fox carcass submission rate. The results confirmed the decrease in fox rabies after the launch of the vaccination campaign. The reduction was independent of both cyclic oscillations in fox rabies and variability in carcass submission rate, thus indicating a positive net effect of the vaccination.

Administration, Oral↗

PubMed1980

Occurrence of (Dirofilaria immitis) in gray fox (Urocyon cinereoargenteus) in Alabama and Georgia.

The occurrence of Dirofilaria immitis in gray fox (Urocyon cineroargenteus) was determined by gross examination, blood samples, and filtered tissue sediments in a sampling of 149 gray foxes taken from Alabama and Georgia during the 1977-78 trapping season. Microfilariae were not found in blood samples obtained from 24 of these gray foxes. Three of 82 male foxes (3.7%) and 1 of 67 female foxes (1.5%) were infected with heartworm. D. immitis rate of infection was 1 of 19 (5.3%) and 3 of 130 (2.3%), respectively, in juvenile and adult gray foxes. Single sex infections with D. immitis occurred in 4 of the 6 foxes, with a maximum nematode burden of approximately eight. Two other infected foxes were encountered separate from this study.

Alabama↗

PubMedDate not supplied

Rabies oral vaccination of foxes during the summer with the VRG vaccine bait.

The vaccination of foxes by distributing vaccine baits in the environment was initiated in France in 1986. Two campaigns per year were carried out: one in the spring and one in the autumn. After the spring campaigns, only 22-52% of fox cubs consumed vaccine baits compared to 75% of the adults and 70-80% of the adults or fox cubs after autumn campaigns. In order to reduce the period of time during which fox cubs do not have access to baits and are not immunised, a vaccination campaign was organised during the summer of 1992 over a contaminated area of 25,748 km2 where vaccines had never previously been given. Vaccine bait stability was assessed during the same summer in the field and their appetence tested on captive foxes. The efficacy of the campaign was evaluated by the relative decrease in rabies incidence and the rate of bait uptake by foxes compared to those from neighbouring areas vaccinated for the first time with the same vaccine during the spring or autumn. Summer vaccination significantly increased (P < 0.01) bait uptake by fox cubs (71%) compared with spring vaccination (39%), but no significant difference was observed for adult foxes. Moreover, the decrease in rabies incidence, measured during the 6-month period following the campaigns was less pronounced after summer vaccination (49% decrease) than when the first vaccination was carried out during the spring or autumn (79 and 72% decrease, respectively). Three campaigns led to an apparent elimination of rabies when the first campaign was performed in the spring or autumn, but only to a 76% decrease in rabies incidence density index when the first campaign was performed during the summer. The high thermostability of the Raboral VRG bait permits its use during the summer for an emergency campaign. For routine vaccination plans, however, the classical calendar of spring and autumn vaccination campaigns should continue to be preferred.

Administration, Oral↗

PubMed1991

A new type of lesion associated with severe fur damage in Canadian ranch foxes and an investigation of possible causes.

In the silver fox, as in its wild ancestor, the red fox (Vulpes vulpes L.), the annual growing phase (anagen) of guard hair follicles occupies at least four months. Severe damage to the hair coat near the end of this growing period was reported in 1985 on many ranches in New Brunswick and Nova Scotia. A histological analysis of serial sections of skin biopsies showed a marked increase in nuclear aberrations in the hair matrix of anagen guard hair follicles. These nuclear aberrations indicated that cells were undergoing apoptosis, a controlled form of cell death. Tissues from affected and unaffected foxes for histological and toxicological analysis, as well as other data, were obtained during visits to 26 ranches in 1986 and 34 ranches in 1987. Histological sections of the 1987 skin samples showed the mean percentage of nuclear aberrations in 43 unaffected foxes to be 0.08 +/- 0.01 (SEM), while that for 49 affected foxes was 0.51 +/- 0.23. The four foxes with the most severe coat damage also had the highest incidences of guard hair matrix cells with nuclear aberrations, ranging from 20 to 100 times greater than the mean for unaffected foxes. The mitotic index of the hair matrix, which normally remains fairly constant during the hair growth phase, was similar for unaffected and affected foxes (1.83 +/- 0.06 and 1.97 +/- 0.07 respectively). Although our analyses of field data have not established a specific environmental factor associated with increased nuclear aberrations, the possible involvement of toxic agents in follicle damage may warrant further investigation.

Adipose Tissue↗

PubMed1991

[Transmissibility and pathogenicity in the red fox of two rabies viruses isolated at a 10 year interval].

Two rabies virus strains collected from naturally infected foxes in France in 1976 and 1986 were inoculated in 2 groups each consisting of 10 foxes (approximately 50 lethal doses50 mouse intracerebral per fox). Another 20 healthy foxes were kept in the same cages as the inoculated animals in order to study the transmission of both strains. All the inoculated foxes became rabid and transmitted rabies to their cage companion. The intervals between death of the inoculated foxes and death of the cage companion were significantly more variable (P less than 0.001) with the earlier strain, from 1 to 33 days compared to the range obtained with the later strain, 10-14 days. However, the mean intervals did not differ. Epidemiological consequences of such a decrease in variability, if confirmed in the field could decrease the epidemiological extent of rabies. Viremia was demonstrated in 2 foxes inoculated with the later strain but we cannot assume this to be a characteristic of this strain compared with the earlier strain. Rabies virus (both strains) was isolated from the saliva of foxes 29 days or less before the onset of clinical symptoms. This last result raises the question of the time limit as regards security before onset of clinical symptoms in animals involved in human contamination.

Animals↗

PubMed1984

[Electrocution of foxes; an ethically acceptable method?].

The routine practice of electrocution of foxes by the Fox final apparatus was observed. The measured current was an average 0.31 (+/- 0.01 s.d.) A, the voltage 111.2 (+/- 18.7) V and the stunning time 3.0 (+/- 0.3) seconds (n = 40). The EEG (electroencephalogram) and the ECG (electrocardiogram) were recorded in 12 foxes. The current was initially applied for 1 sec. Ten foxes showed a general epileptiform insult (= unconscious) which was interrupted by a heart fibrillation, based on the EEG and ECG traces. Two foxes showed a general epileptiform insult while the heart fibrillation was incomplete. These two foxes recovered again. After the second stunning with a duration of about 3 seconds the heart fibrillation was complete in these animals. In the EEG and ECG experiments the voltage was on average 110.0 (+/- 7.9) V, the current 0.40 (+/- 0.11) A and the stunning time 1.1 (+/- 0.3) seconds (n = 12). The observations of the method in practice and the EEG and ECG measurements suggest that electrocution of foxes by the Fox final apparatus is a quick and effective method if the current delivery is at least 3 to 4 seconds.

Animals↗

PubMed1981

Response of gray foxes to modified live-virus canine distemper vaccines.

Ten gray foxes seronegative for canine distemper virus were vaccinated with 1 of 3 commercial modified live-virus canine distemper vaccines. Of 5 foxes receiving vaccine A (chicken tissue culture origin), 4 developed significant titers (greater than or equal to 1:100) of neutralizing antibody to canine distemper virus and remained clinically normal after vaccination. Two of 3 foxes vaccinated with vaccine B (canine cell line origin) and both foxes receiving vaccine C (canine cell line origin) died of vaccine-induced distemper. Five unvaccinated control foxes died of distemper after a known occasion for contact transmission of virus from a fox vaccinated with vaccine B. The results suggested that the chicken tissue culture origin modified live-virus canine distemper vaccine is probably safe for normal adult gray foxes, whereas the canine cell origin vaccines are hazardous. The results of this study tended to corroborate anecdotal experiences of veterinarians who have observed that gray foxes frequently die from distemper soon after vaccination with modified live-virus canine distemper vaccines.

Animals↗

PubMed1996

Gastrointestinal helminths of Arctic foxes (Alopex lagopus) from different bioclimatological regions in Greenland.

Nine species of gastrointestinal helminths were recovered from 254 arctic foxes (Alopex lagopus) from 8 different localities in Greenland. Prevalences of infection with the helminth species differed from area to area: Toxascaris leonina (39-68%), Strongyloides stercoralis (0-14%), Mesocestoides lineatus (0-58%), Diphyllobothrium dendriticum (0-15%), Taenia ovis krabbei (0-70%), Cryptocotyle sp. (0-3%), Plagiorchis elegans (0-6%), and Polymorphus sp. (0-3%). Additionally, a Taenia species, which appears to be different from T. ovis krabbei, had a prevalence of 24% but only on the east coast of Greenland. In general, the composition of the helminth fauna of arctic foxes in Greenland showed distinct differences geographically. Thus, the diversity of helminth species in foxes caught in the northern districts of Greenland seems lower than in the southern districts; only nematode species with direct life cycles were represented equally in all parts of the country. The diversity of the surrounding fauna, and thereby the food items available for the foxes, seems to determine the spectrum of helminth species. Helminths requiring rodents as intermediate hosts were absent on the west coast, even in the areas in northwest Greenland in close proximity to the Canadian Archipelago. Foxes from air bases, which are known to feed intensively on garbage, harbored similar numbers of species compared to foxes from settlements in the same regions. The number of T. leonina in animals less than 1 yr of age was significantly higher than in older individuals. For M. lineatus, the prevalence of infection was found to increase and worm burdens to decrease with increasing host age. Infections with 2 or more helminth species were most frequent in older animals (47% in foxes > or = 4 yr old and 33% in foxes < 4 yr old).

Animals↗

PubMed1995

Clinical picture and antibody response to experimental Sarcoptes scabiei var. vulpes infection in red foxes (Vulpes vulpes).

Three red foxes (Vulpes vulpes) were experimentally infected with Sarcoptes scabiei isolated from a naturally infected wild red fox. A fourth red fox served as a control. The first signs of sarcoptic mange became evident on the 31st day post infection (dpi). The signs gradually increased thereafter and between dpi 49 and 77 characteristic lesions of hyperkeratosis developed. Two of the infected foxes developed severe sarcoptic mange, and one of these animals died on dpi 121. The third fox developed a chronic hyperkeratotic lesion on its back, at the site where the mites had been applied. On dpi 127 the surviving foxes were treated systemically with ivermectin, and within 4 weeks the skin lesions had healed except on the pinnae of one animal. Antibodies to S. scabiei var. vulpes were demonstrated in the infected foxes by an ELISA with which seroconversion was seen around 4 weeks post infection (wpi). Western blot analysis of sequential sera of the infected animals demonstrated antibody activity consistently after the 2nd wpi. The fourth, non-infected, fox did not show any skin lesions throughout the experimental period nor any specific antibodies to S. scabiei var. vulpes.

Animals↗