[Fox population and fox rabies in Lower Saxony with regard to the landscape structure].
Explore the source record for details and available documents.
Animals↗
SEARCH · PubMed Health
Results for “Foxes”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Peripheral plasma progesterone concentrations in pregnant and non-pregnant greyheaded flying-foxes (Pteropus poliocephalus) and little red flying-foxes (P. scapulatus).
Blood was collected from breeding-season and pregnant P. poliocephalus females shot in the wild and from captive pregnant and ovariectomized P. poliocephalus and P. scapulatus females. Peripheral plasma progesterone concentrations measured by radioimmunoassay were similar to those obtained by gas chromatography-mass spectroscopy: in intact non-pregnant P. poliocephalus females without corpora lutea (CLs) values ranged from 2 to 30 ng mL-1; after ovariectomy, they ranged from 1 to 85 ng mL-1. A significant source of progesterone in these bats may be the adrenal. In P. poliocephalus, peripheral plasma progesterone concentrations showed relatively little change over the breeding season or in early pregnancy when a CL formed, but increased from mid pregnancy to reach 200-800 ng mL-1 in late pregnancy. A mid-pregnancy ovary with CL contained 2.80 ng progesterone whereas the contralateral ovary contained 0.13 ng. Overall, CL size decreased during pregnancy and was negatively correlated with plasma progesterone concentrations. In late pregnancy, the main source of progesterone appears to be the placenta; plasma concentrations increase with placental growth and are significantly correlated with placental weight, and placentas contain 4-8 micrograms progesterone g-1. There was no evidence that progesterone concentrations fall before parturition. Limited observations indicated that peripheral progesterone concentrations follow similar patterns in P. scapulatus.
Animals↗
[Control of sylvatic rabies with special consideration of the decimation of the fox population by fumigation of fox holes].
Explore the source record for details and available documents.
Animals↗
A phylogenetic analysis of basal metabolism, total evaporative water loss, and life-history among foxes from desert and mesic regions.
We measured basal metabolic rate (BMR) and total evaporative water loss (TEWL) of species of foxes that exist on the Arabian Peninsula, Blanford's fox (Vulpes cana) and two subspecies of Red fox (Vulpes vulpes). Combining these data with that on other canids from the literature, we searched for specialization of physiological traits among desert foxes using both conventional least squares regression and regressions based on phylogenetic independent contrasts. Further, we explored the consequences of reduced body size of foxes on life history parameters such as litter size and neonate mass. For Blanford's foxes, Red foxes from the central desert of Arabia, and Red foxes from the more mesic Asir mountains, body mass averaged 1,285 +/- 52 g, 1,967 +/- 289 g, and 3,060 +/- 482 g, respectively, whereas mean BMR, during summer, was 304.5 +/- 32.3 kJ/day, 418.0 +/- 32.4 kJ/day, and 724.1 +/- 120.2 kJ/day (+/- SD). An analysis of covariance with body mass as a covariate showed no statistical differences in BMR among foxes. Analysis of covariance indicated that Red fox from the Asir mountains had a higher TEWL than Red foxes from central Arabia or than Blanford's foxes also from the mountains. Comparisons of all species of desert and mesic foxes showed no significant differences in BMR, nor did desert foxes have a significantly lower BMR than other carnivores. TEWL of desert foxes was lower than other more mesic carnivores; deviations in TEWL ranged from -17.7% for the Fennec fox (Fennecus zerda) to -57.4% for the Kit fox (Vulpes velox). Although desert foxes have a BMR comparable to other more mesic species, it appears that desert foxes do have a smaller body mass, lowering overall energy requirements. We attribute this reduction in body size to the "resource limitation hypothesis" whereby natural selection favors smaller individuals in a resource-limited environment, especially during periods of severe food shortage. However, until common garden experiments are performed, developmental plasticity and acclimation cannot be ruled out as contributors to this pattern.
Adaptation, Physiological↗
Experimental infection of European red foxes (Vulpes vulpes) with canine herpesvirus.
We report on the pathogenicity of canine herpesvirus (CHV) for European red foxes. In the first experiment, we inoculated 10 adult foxes intravenously with a canine isolate of CHV. All foxes became infected and shed CHV in saliva and genital secretions for up to 14 days post-inoculation (p.i.) as evaluated by PCR and/or by virus isolation. All foxes developed clinical signs such as fever, lethargy and evidence of respiratory tract disease. Two foxes died on day 6 p.i., one on day 7 p.i., and one fox was euthanased on day 6 p.i. Tissues taken from the four dead foxes were positive for CHV by PCR. The remaining six foxes recovered after approximately 14 days p.i. Virus particles with morphology typical of herpesviruses were found by electron microscopy in the liver of an infected animal. All surviving foxes developed serum anti-CHV antibodies. In a second experiment, six foxes were dosed perorally with CHV and paired with six untreated controls. Neither the perorally dosed nor the in-contact control foxes developed clinical signs of disease. Infectious CHV was not isolated from any of the dosed or the in-contact foxes but all perorally-infected foxes and one of the in-contact foxes tested PCR-positive for CHV on several occasions p.i. All perorally-infected foxes, but none of the in-contact foxes, seroconverted. In summary, intravenous CHV inoculation caused a clinical disease in adult foxes much more severe than observed in experimentally-infected adult dogs. No clinical disease or virus spread was observed after peroral dosing although viral infection occurred as evidenced by seroconversion.
Administration, Oral↗
A marker set for construction of a genetic map of the silver fox (Vulpes vulpes).
The silver fox, a variant of the red fox (Vulpes vulpes), is a close relative of the dog (Canis familiaris). Cytogenetic differences and similarities between these species are well understood, but their genomic organizations have not been compared at higher resolution. Differences in their behavior also remain unexplained. Two silver fox strains demonstrating markedly different behavior have been generated at the Institute of Cytology and Genetics of the Russian Academy of Sciences. Foxes selected for tameness are friendly, like domestic dogs, while foxes selected for aggression resist human contact. To refine our understanding of the comparative genomic organization of dogs and foxes, and enable a study of the genetic basis of behavior in these fox strains, we need a meiotic linkage map of the fox. Towards this goal we generated a primary set of fox microsatellite markers. Four hundred canine microsatellites, evenly distributed throughout the canine genome, have been identified that amplify robustly from fox DNA. Polymorphism information content (PIC) values were calculated for a representative subset of these markers and population inbreeding coefficients were determined for tame and aggressive foxes. To begin to identify fox-specific single nucleotide polymorphisms (SNPs) in genes involved in the neurobiology of behavior, fox and dog orthologs of serotonin 5-HT1A and 5-HT1B receptor genes have been cloned. Sequence comparison of these genes from tame and aggressive foxes reveal several SNPs. The close relationship of the fox and dog enables canine genomic tools to be utilized in developing a fox meiotic map and mapping behavioral traits in the fox.
Aggression↗
[Annual testing of immunity in foxes after oral rabies immunization].
Ten young foxes were orally immunized with a "Rabies vaccine for oral immunization of foxes--LYSVULPEN por. a.u.v.," batch 69 10 93, commercially manufactured by the company Bioveta, s.r.o. at Ivanovice in Haná. The vaccine contained 1.8 x 10 of rabies vaccination virus, strain SAD-Bern, in a vaccination dose. Three foxes were used as control animals without vaccination. Blood samples were taken before the beginning of the experiment in all test foxes, and then in three-month intervals. The last blood samples were taken just before the beginning of a challenge experiment and two months after challenge in the foxes that survived. A challenge test was done in all foxes (vaccinated and nonvaccinated ones) a year after single oral immunization against rabies. Challenge virus was prepared from the salivary gland of a naturally infected fox living in the territory of the Czech Republic. Street virus was applied to each fox i.m. to a great depth to both masticatory muscles (musculus masseter) at a total dose of 10,000 MICLD50. The experimental animals were 60 days under observation. Tab. I shows the titers of virus-neutralizing rabies antibodies after oral immunization against rabies in all experimental foxes. Except fox no. 8, the formation of specific virus-neutralizing rabies antibodies was recorded in all animals after they had eaten vaccination baits. The antibodies were detected throughout the whole year of observation. Tab. II shows the results of challenge test. Out of the nine vaccinated foxes (fox no. 9 died before infection) only fox no. 8 died from rabies, the other treated foxes were protected from rabies (89% rate of protection). Tab. III presents the results of laboratory examination. Tetracycline was demonstrated in all treated foxes (a vaccination proof). Death due to rabies was demonstrated in control animals without vaccination and in fox no. 8. The results achieved in the Czech Republic for oral immunization of foxes against rabies with the vaccination strain SAD-Bern document very good efficacy of the vaccine manufactured by the company Bioveta, s.r.o., in Ivanovice in Haná since 1992. Oral immunization largely improved the infection situation in the Czech Republic. A total of 1,501 cases of rabies infection were recorded at the start of vaccination in 1989 while it was only 221 cases in 1994 (a decrease in then number of foci by 85%).
Administration, Oral↗
Measurement of plasma hydroperoxide concentration by FOX-1 assay in conjunction with triphenylphosphine.
INTRODUCTION: Hydroperoxides are well-recognized reactive oxygen species which are associated with oxidative stress, a phenomenon of current clinical interest as oxidative stress is associated with a number of disease condition. Ferrous ion oxidation xylenol orange (FOX) methods of hydroperoxide estimation has outdated other methods available for hydroperoxide estimation. Two versions FOX assays are described in the literature, FOX-1 and FOX-2, in which FOX-1 is more sensitive. METHODS: we increased the sensitivity of FOX-1 assay by stabilizing the reagent pH 1.7-1.8. Analogous to FOX-2 assay, we have modified FOX-1 assay by using it in conjunction with triphenylphosphine and butylated hydroxytoluene, thus increasing the specificity of FOX-1 assay for hydroperoxide. By modified FOX-1 method, we estimated plasma hydroperoxide concentration of normal human subjects and of diabetic patients and compared with FOX-2 method. RESULTS: The FOX-1 method showed a significant high value of plasma hydroperoxide concentration compared to FOX-2 method both in normal subjects and diabetic patients with a significant correlation. By modified FOX-1 method, the recovery percentage of cumene hydroperoxide was better in biological samples when compared to FOX-2 method. CONCLUSION: The modified FOX-1 method is equally specific for hydroperoxide determination when compared to FOX-2 but is more sensitive.
Ascitic Fluid↗
Fox-2 mediates epithelial cell-specific fibroblast growth factor receptor 2 exon choice.
Alternative splicing of fibroblast growth factor receptor 2 (FGFR2) transcripts occurs in a cell-type-specific manner leading to the mutually exclusive use of exon IIIb in epithelia or exon IIIc in mesenchyme. Epithelial cell-specific exon choice is dependent on (U)GCAUG elements, which have been shown to bind Fox protein family members. In this paper we show that FGFR2 exon choice is regulated by (U)GCAUG elements and Fox protein family members. Fox-2 isoforms are differentially expressed in IIIb+ cells in comparison to IIIc+ cells, and expression of Fox-1 or Fox-2 in the latter led to a striking alteration in FGFR2 splice choice from IIIc to IIIb. This switch was absolutely dependent on the (U)GCAUG elements present in the FGFR2 pre-mRNA and required critical residues in the C-terminal region of Fox-2. Interestingly, Fox-2 expression led to skipping of exon 6 among endogenous Fox-2 transcripts and formation of an inactive Fox-2 isoform, which suggests that Fox-2 can regulate its own activity. Moreover, the repression of exon IIIc in IIIb+ cells was abrogated by interfering RNA-mediated knockdown of Fox-2. We also show that Fox-2 is critical for the FGFR2(IIIb)-to-FGFR2(IIIc) switch observed in T Rex-293 cells grown to overconfluency. Overconfluent T Rex-293 cells show molecular and morphological changes consistent with a mesenchymal-to-epithelial transition. If overconfluent cells are depleted of Fox-2, the switch from IIIc to IIIb is abrogated. The data in this paper place Fox-2 among critical regulators of gene expression during mesenchymal-epithelial transitions and demonstrate that this action of Fox-2 is mediated by mechanisms distinct from those described for other cases of Fox activity.
Alternative Splicing↗
Dietary taurine deficiency and dilated cardiomyopathy in the fox.
Taurine deficiency has been implicated as a potential cause of dilated cardiomyopathy. However, the relationship between taurine and myocardial function is presently unclear. The purpose of this study was to determine whether dilated cardiomyopathy in the fox is associated with dietary taurine deficiency. A total of 68 foxes from farms with a history of death caused by dilated cardiomyopathy and 14 foxes from a farm with no history of dilated cardiomyopathy were studied. Dilated cardiomyopathy was diagnosed by echocardiography in 48% of the foxes from one farm with a positive history and in none of the foxes from the control farm. Foxes less than 9 months of age were more commonly affected than older foxes (p = 0.03). Plasma taurine concentrations were significantly less (p less than 0.01) in foxes that had dilated cardiomyopathy (26.8 +/- 16.4 nmol/ml) than in the control foxes (99.3 +/- 60.2 nmol/ml). A significantly higher (p less than 0.01) incidence of dilated cardiomyopathy was present in foxes with a history of a sibling or offspring that died of dilated cardiomyopathy than in foxes without a family history of cardiac death. In one fox with dilated cardiomyopathy that was tested, the myocardial taurine concentration was lower (1.7 mumol/gm wet weight) than that of control foxes (7.3 +/- 1.6 mumol/gm wet weight). Hepatic cysteinesulfinic acid decarboxylase activity was significantly less (p less than 0.001) in foxes with dilated cardiomyopathy (0.97 +/- 0.2 nmol/mm.mg protein) than in control foxes (2.11 +/- 0.07 nmol CO2/mm.mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Primary multiplication site of the vaccinia-rabies glycoprotein recombinant virus administered to foxes by the oral route.
The primary multiplication site of VVTGgRAB, a recombinant vaccinia virus (VV) expressing the rabies virus G glycoprotein, was studied in comparison with that of the parental VV Copenhagen strain, after oral administration to foxes. Foxes were fed with 10(8) TCID50 of either VVTGgRAB or VV and were sacrificed 12, 24, 48 or 96 h after inoculation. Both viruses were detected by viral isolation in the tonsils during the first 48 h after inoculation at titres between 10(2) and 10(4.3) TCID50/ml. Indirect immunofluorescence confirmed the presence of the virus in tonsils of some of the foxes. The polymerase chain reaction allowed the detection of VVTGgRAB in the tonsils of both of two foxes tested after 24 h, three of three foxes after 48 h, in the buccal mucosa of one of two foxes tested after 24 h and two of three foxes after 48 h and in the soft palate of one of two foxes tested after 24 h and one of three foxes after 48 h. VV was detected in the tonsils of one fox tested after 48 h, in the buccal mucosa of another fox tested after 24 h, and in the first fox after 48 h by the same reaction. Foxes were inoculated with virus isolated from fox tonsils 24 h after oral administration (with or without cell culture amplification) to perform back passages. No virus could be isolated in either case after this passage. The innocuity of VVTGgRAB was also demonstrated when foxes were inoculated with passaged virus.
Administration, Oral↗
Responses of red foxes to first and second infection with Sarcoptes scabiei.
The clinical response of red foxes (Vulpes vulpes) to the mange mite, Sarcoptes scabiei, was characterized by infection of five, 4-mo-old red foxes with S. scabiei originally isolated from a wild red fox. The infected foxes and three uninfected control foxes were monitored with weekly complete blood counts and biweekly serum chemistry profiles, hypersensitivity tests, and evaluation of skin biopsies. After 7 wk, the foxes were treated and held free of infection for 2 mo. Six foxes, three previously infected and three with no history of exposure, were then infected with the same isolate of S. scabiei and followed for another 7 wk; two additional previously infected foxes were held as treatment controls, and two foxes with no history of exposure as naive controls. All infected foxes developed significant immediate (Type I) hypersensitivity reactions to a S. scabiei mite extract within 2 wk of exposure and maintained this reaction as long as 4 mo after clearance of mites. Pronounced mast cell hyperplasia and infiltration with eosinophils were the earliest inflammatory cell responses noted in biopsy samples from infected foxes and were maintained throughout infection. Infected foxes also showed significant increases in white blood cell counts, due primarily to increases in numbers of circulating neutrophils and eosinophils. Clinical response, severity of disease, and relative numbers of mites per cm2 of skin of previously infected foxes and foxes undergoing their first infection did not differ. These results show that red foxes develop strong immediate hypersensitivity reactions to S. scabiei but, under our experimental conditions, did not exhibit resistance to reinfection.
Animals↗
Genetic and molecular analysis of fox-1, a numerator element involved in Caenorhabditis elegans primary sex determination.
fox-1 was previously identified as a candidate numerator element based on its overexpression phenotype. FOX-1 is an RRM-type RNA-binding protein, which can bind RNAs in vitro. Western analysis detects FOX-1 throughout development. fox-1::lacZ comes on ubiquitously early during embryogenesis. Postembryonically, fox-1::lacZ is expressed sex specifically in a subset of cells in the head and tail. We describe a Tc1-derived deletion allele [fox-1(Delta)] that removes the RRM domain. fox-1(Delta) confers no phenotype in XXs, but can rescue XO-specific lethality and feminization caused by duplications of the left end of the X. fox-1(Delta) synergizes with putative numerators, resulting in abnormal XX development. Genetic analysis indicated that fox-1(Delta) leads to a slight increase in xol-1 activity, while fox-1(gf) leads to partial loss of xol-1 activity, and xol-1 is epistatic to fox-1. RNase protection experiments revealed increased levels of the 2.2-kb xol-1 message in fox-1(Delta) animals, and reduced levels in fox-1(gf) animals. Additionally, fox-1(Delta) impairs male mating efficiency, which, we propose, represents another function of fox-1, independent of xol-1 and its role in sex determination.
Animals↗
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.
Animals↗
Genetic polymorphism of plasma alpha 1 B-glycoprotein and transferrin in arctic and silver foxes.
Plasma samples of 235 foxes from 38 complete families (14 of arctic foxes, 21 of silver foxes and 3 with arctic x silver fox hybrid offspring) were analysed by one-dimensional horizontal polyacrylamide gel electrophoresis (PAGE) pH 9.0 followed by general-protein staining of gels. A major postalbumin of fox plasma was identified as alpha 1B-glycoprotein (alpha 1B) by using immunoblotting with antiser m specific to human or pig plasma alpha 1B. Four codominant, autosomal alleles of alpha 1B were found in arctic foxes. Two transferrin (TF) alleles (TfF, TfS) were observed in arctic foxes and two (TfD, Tff) in silver foxes; the TF F type of both of the fox species showed identical electrophoretic mobilities. The arctic foxes showed a high degree of polymorphism for both TF and alpha 1B. The silver foxes showed a scarce polymorphism of TF and were monomorphic for alpha 1B. The arctic fox, silver fox and their hybrids could be clearly differentiated from one another by their plasma protein patterns obtained by the PAGE method.
Alleles↗
Corticosteroid treatment does not reactivate canine herpesvirus in red foxes.
To study canine herpesvirus (CHV) reactivation from red foxes (Vulpes vulpes), 29 foxes with varying CHV antibody and CHV carrier status were treated with methylprednisolone acetate, a glucocorticosteroid drug with prolonged immunosuppressive effect in dogs. In the first experiment, 17 foxes with unknown CHV carrier status were treated once with methylprednisolone: in the second experiment, five foxes were treated twice, 4 mo after being intravenously CHV infected; and in the third experiment, six foxes were treated five times, 11 mo after peroral CHV infection. Infectious CHV was not isolated after treatment from either naturally or experimentally CHV-infected foxes or from untreated, CHV-seronegative in-contact foxes. Canine herpesvirus DNA was not detectable in mucosal secretions or white blood cells of any of the foxes, whereas all trigeminal ganglia of experimentally CHV-infected foxes were polymerase chain reaction-positive. In CHV-seropositive foxes, anti-CHV antibody titers did not change with time after treatment, and CHV-seronegative in-contact controls did not seroconvert. Hematologic parameters remained mostly unchanged. We conclude that CHV is not as easily reactivated in foxes following corticosteroid treatment as in dogs, although there was no obvious sign of immunosuppression. Canine herpesvirus was not spread from virus carriers to naive in-contact foxes, which may be among possible explanations for the reported low CHV prevalence in wild foxes.
Animals↗
alpha- and beta-FOX-7, polymorphs of a high energy density material, studied by X-ray single crystal and powder investigations in the temperature range from 200 to 423 K.
The alpha-beta phase transition in the novel energetic material 1,1-diamino-2,2-dinitroethylene, C2H4N4O4 (FOX-7), has been studied by single-crystal X-ray investigations at five different temperatures over the 200-393 K range. In these investigations, the positions of the hydrogen atoms were experimentally determined without any geometric constraints. In addition, X-ray powder investigations using the Guinier technique have been performed to characterize the beta-phase up to 423 K. The alpha-beta phase transition at 389 K is first order, shows a discontinuous increase of the molar volume and entropy (DeltaV = 1.75 cm3/mol, X-ray investigation; DeltaS = 1.5 cal/K mol, DSC analysis), and can be classified as displacive. The hitherto unknown structure of beta-FOX-7 was solved at 393 K and showed simple structural relations to the alpha-polymorph. The characteristic bonding in wave-shaped layers is now found for beta-FOX-7 (P2(1)2(1)2(1), z = 4, a= 6.9738(7) A, b = 6.635(1) A, c = 11.648(2) A, 393 K), as well as for alpha-FOX-7 (P2(1)/n, z = 4, a = 6.9467(7) A, b = 6.6887(9) A, c = 11.350(1) A, beta = 90.143(13) degrees , 373 K). Interestingly, whereas the intramolecular C-C, C-N, N-O, and N-H bond distances remain nearly unchanged for both polymorphs over the whole temperature range from 200 to 393 K, the two nitro groups deviate strongly from the molecular plane formed by the two carbon and two amino nitrogen atoms. In alpha-FOX-7 at 373 K, the nitro groups are twisted -47 and +6 degrees with respect to the carbon-carbon bond, but in beta-FOX-7 at 393 K, these twist angles are changed to -36 and +20 degrees . Within the layers, the FOX-7 molecules show strong pi-conjugation and extensive intra- and intermolecular hydrogen bonding. In this investigation, we have been able to show that alpha- and beta-FOX-7 build up different nets of intermolecular hydrogen bonds. In alpha-FOX-7, each oxygen atom of the nitro groups is involved in two hydrogen bonds resulting in two intramolecular and six intermolecular hydrogen bonds. But in beta-FOX-7 this coordination changes, and half of the oxygen atoms build up two and the other half build up three hydrogen bonds leading to two intramolecular and eight intermolecular hydrogen bonds. The average intermolecular hydrogen bond distance increases slightly from 2.31 A in alpha-FOX-7 to 2.52 A in beta-FOX-7. The C-NO2 bonds are of particular interest because they are referred to as the detonation trigger. It has been suggested that these bonds could be strengthened by the extensive intermolecular hydrogen bonding within the layers in both polymorphs. Such bond strengthening via cooperative effects was proposed in earlier DFT calculations on FOX-7 and may be one key to understanding its low sensitivity and high activation energy to impact.
Journal Article↗
Comparison of heavy metal concentrations in tissues of red foxes from adjacent urban, suburban, and rural areas.
The red fox (Vulpes vulpes) is a representative of the canid family with wide distribution in the Northern Hemisphere and Australia. The increasing utilization of urbanized habitats by red foxes prompted us to test whether this species may be used to monitor the presence of anthropogenic pollutants in cities or suburbs. For that purpose, we compared the concentrations of heavy metals (Cd, Pb, Cu, Zn) in foxes from urban, suburban, and rural areas within the municipality of Zürich (Switzerland). The kidney and liver of suburban and rural foxes contained the highest Cd concentrations, whereas urban foxes contained the highest Pb levels. In the kidney of suburban foxes, Cd concentrations increased from a median value of 0.73 mg/kg in juvenile animals to 1.82 mg/kg in adults. Similarly, the liver of suburban foxes contained increasing Cd levels from a median of 0.21 mg/kg in juvenile animals to 0.94 mg/kg in adults. An age-dependent storage of Cd was also found in foxes from the rural surroundings, but no such accumulation occurred in urban foxes from the city center, where even adult animals contained very low Cd levels. Conversely, foxes from the urban center were characterized by elevated Pb concentrations during the first 2 years of life, but this transient Pb accumulation was absent in suburban or rural animals. The liver of juvenile foxes contained a median Pb concentration of 0.99 mg/kg in the city compared to only 0.47 and 0.37 mg/kg in the suburban and rural area, respectively. Thus, we found that animals from separate environmental compartments contain different patterns of tissue residues, implying that red foxes may serve as a bioindicator species to detect certain toxic hazards in urbanized habitats.
Animals↗