Prevalence of selected pathogenic microbial agents in the red fox (Vulpes fulva) and gray fox (Urocyon cinereoargenteus) of southwestern Wisconsin

Free-ranging red foxes (Vulpes fulva) and gray foxes (Urocyon cinereoargenteus) were trapped in southwestern Wisconsin. Fox sera were tested to determine the prevalence of antibody for five different Leptospira interrogans serovars, canine distemper virus (CDV), infectious canine hepatitis virus (ICHV), and Franciscella tularensis infections. Grippotyphosa was the most prevalent leptospiral serovar antibody observed. Twenty-five of 53 (47%) red foxes and 11 of 36 (31%) gray foxes had specific antibodies to grippotyphosa. Juvenile foxes had geometric mean antibody titers to grippotyphosa significantly higher (P less than 0.05) than those of the adults of both species. CDV antibody was detected in sera of red foxes only. Six of 57 (11%) red foxes had CDV antibody. ICHV antibody was detected in 2 of 57 (3%) red foxes and 3 of 32 (9%) gray foxes. Antibody to F. tularensis was not detected in any fox sera.     

Identification of the Tibetan fox (Vulpes ferrilata) and the red fox (Vulpes vulpes) by copro-DNA diagnosis

Studies on feeding habits based on faeces dissecting are imperative to understand the natural history of Tibetan foxes and their functions in the transmission of a lethal zoonotic parasite, Echinococcus multilocularis. However, Tibetan foxes and red foxes live sympatrically on the Tibetan plateau, China. Therefore, the faeces of Tibetan foxes must be distinguished from those of red foxes. We established a diagnostic method to distinguish the faeces of the two species by amplifying a portion of the mitochondrial cytochrome b gene (cytb) and digesting with the restriction enzymes BamHI and SspI, to produce specific diagnostic banding patterns. This PCR-RFLP assay enabled rapid, accurate and easily performed identification and differentiation of the two species.     

LHRH and LH release in the red fox Vulpes vulpes L

Pituitary responsiveness to exogenous LHRH was studied in vivo and in vitro in the female red fox, a mono-oestrous species. In vivo, the ability of the pituitary to release LH in response to a single injection of LHRH (2 micrograms/kg) was determined at various stages of the reproductive cycle. The greatest responsiveness is observed during the preovulatory period, the lowest during the luteal phase. During the anoestrus phase, the responsiveness is reduced by more than 50% in lactating females compared to non lactating females. In vitro, dispersed fox anterior pituitary cells were exposed four times to LHRH (10(-9) M), hourly, for 8 min. Pituitary cells were taken from lactating and non lactating females. The cells are not sensitive to LHRH in lactating females but become more and more sensitive after weaning. It is suggested the inhibitory influence of lactation could be the result of prolactin-ovarian steroids-gonadotrophins interactions.     

Acute disseminated toxoplasmosis in a red fox (Vulpes vulpes)

A red fox (Vulpes vulpes) with signs of neurological disease was captured in Fairmount Park, Philadelphia, Pennsylvania (USA). The animal died in captivity and was examined because of suspected rabies. The liver had pale foci up to 4 mm in diameter. Foci of necrosis were associated with Toxoplasma gondii tachyzoites in several organs including liver, lungs and adrenal glands. Rabies antigen and distemper virus inclusions were not detected. The diagnosis of acute disseminated toxoplasmosis was confirmed by immunohistochemical staining.     

Systemic AA amyloidosis in the red fox (Vulpes vulpes)

Amyloid A (AA) amyloidosis occurs spontaneously in many mammals and birds, but the prevalence varies considerably among different species, and even among subgroups of the same species. The Blue fox and the Gray fox seem to be resistant to the development of AA amyloidosis, while Island foxes have a high prevalence of the disease. Herein, we report on the identification of AA amyloidosis in the Red fox (Vulpes vulpes). Edman degradation and tandem MS analysis of proteolyzed amyloid protein revealed that the amyloid partly was composed of full‐length SAA. Its amino acid sequence was determined and found to consist of 111 amino acid residues. Based on inter‐species sequence comparisons we found four residue exchanges (Ser31, Lys63, Leu71, Lys72) between the Red and Blue fox SAAs. Lys63 seems unique to the Red fox SAA. We found no obvious explanation to how these exchanges might correlate with the reported differences in SAA amyloidogenicity. Furthermore, in contrast to fibrils from many other mammalian species, the isolated amyloid fibrils from Red fox did not seed AA amyloidosis in a mouse model.     

Variations of the chromosome number in the red fox (Vulpes vulpes)

The chromosome number in peripheral blood cells of five individuals of Vulpes vulpes (Red Fox) is shown to vary between 35 and 39. This variation is due to loss or gain of the smallest autosome, which it is suggested is heterochromatic and does not have any major influence on the phenotype. This species demonstrates variation in chromosome number both between and within individuals.     

Short microsatellite DNA markers for the red fox (Vulpes vulpes)

Seven short microsatellite loci (< 165 bp) were characterized for red foxes for the amplification of degraded DNA extracted from historical samples. Following polymerase chain reaction (PCR) using primers developed in the domestic dog, red fox‐specific primers were designed within the flanking regions. The number of detected alleles ranged between six and 15 alleles and the expected heterozygosities ranged between 0.67 and 0.92. No deviations from Hardy–Weinberg equilibrium were detected for any of the markers.     

Detection of rabies virus antibodies in Brazilian free-ranging wild carnivores

Rabies virus is a pathogen of major concern in free-ranging wild carnivores in several regions of the world, but little is known about its circulation in Brazilian wild carnivores. Sera from 211 free-ranging wild carnivores, captured from 2000 to 2006 in four locations of two Brazilian biomes (Pantanal and Cerrado), were tested for rabies antibodies. Twenty-six individuals (12.3%) had neutralizing antibody titers ≥0.10 IU/ml. The four sampled locations had antibody-positive animals, suggesting that Rabies virus circulates in all of these regions. Results underscore the risk posed by rabies for conservation of Brazilian carnivores and the possibility of the animals acting as reservoirs for the Rabies virus.     

Geography of dental polymorphism in the red fox Vulpes vulpes and its evolutionary implications

Frequency distributions of dental morphotype characters (groups of morphotypes from A to S) in 43 red fox Vulpes vulpes (Linnaeus, 1758) populations from the Holarctic region were analysed. Definite but different geographical gradients in morphotype dental patterns were found both in the Palearctic and Nearctic. In the Nearctic, a great number of characters present geographical gradient related to longitude whereas, in the Palearctic, gradient relates to latitude. Mean annual temperature and mean annual sum of precipitations play a significant role in shaping the geographical variation of morphotype characters. The shape of the teeth in the centre of the morphogenetic field is more heavily geo-climatically conditioned than the morphotype characters in the teeth at the ends of the cheek teeth field. There was an attempt to reconstruct the evolutionary changes in the morphotype dental pattern in the V. vulpes line. The morphotype pattern in the red fox dentition partially follows the phylogeographical evolutionary trends in Canidae in the northern hemisphere. However, the picture of morphotype variation is influenced by both earlier episodes of human interference (reintroductions of foxes in North America) and the recent phenomenon of heavy opportunism of the species.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 61–84.     

Environmental factors influencing the use of habitat in the red fox, Vulpes vulpes

The seasonal variation in habitat selection and its determinants were assessed weekly for a sample of three dog-foxes and two vixens in an ecotonal area of the Tuscan coast, in Italy. The most utilized habitats were the maquis (scrubwood), meadows and pinewood. In the cold season the maquis was preferred to any other habitat, but in the warm months foxes made extensive use of meadows. On the other hand, no clear seasonal pattern of use was detectable for the pinewood. Food habits showed a seasonal variation: juniper berries were the staple food, forming by far the greatest part of the diet during the whole study, except in late spring through midsummer, when beetles and grasshoppers predominated. Availability indices for each main food category were calculated on a weekly basis. Distribution of juniper berries was found to be clumped, whereas insects were dispersed. It was also assessed that the former occurred almost entirely in the pinewood, while the latter inhabited mainly meadows and, to a lesser extent. the pinewood. Measures of fox activity in the three habitats were also taken. The fox diet correlated well to the seasonal abundance of the important food resources, which in turn was significantly correlated to meteorologic factors (temperature, number of rainy days). Surprisingly, the seasonal activity in the pinewood was inversely correlated to local food availability, i.e. juniper berries. This can be explained by the clumpedness of this food resource which, when abundant, allows foxes to become quickly satiated and to retreat to other, more preferred habitat such as the maquis. Such results caution against assuming that extensive time spent in a habitat is an indication of proportional feeding dependence on it.     

Mitochondrial DNA phylogeography of the red fox (Vulpes vulpes) in northern Japan

Mitochondrial DNA variation in the cytochrome b (cyt b) gene and the control region was examined in the red fox Vulpes vulpes from Japan, with special focus on the population divergence between Hokkaido and northern Honshu. Resultant haplotypes from Hokkaido were subdivided into two distinct groups (I and II), with an average genetic distance of 0.027 for cyt b. Divergence time is roughly estimated to be 1-2 million years ago, given that the conventional divergence rate of the mammalian cyt b gene is 2% per million years. Notably, Group II was only found in Hokkaido, whereas Group I comprised haplotypes from Honshu, Kyushu (Japan), eastern Russia, and Europe, as indicated by a comparison of our own data to the literature. On the other hand, judging from constructed trees, Group I haplotypes from Hokkaido appeared to differ from those from other parts of Japan, i.e., Honshu and Kyushu. This implies that Blakiston's Line, which demarcates the boundary between Hokkaido and Honshu, has been an effective barrier and has allowed the structuring of genetic variation in maternal lineages. Thus, these results suggest that the Hokkaido population, which is sometimes referred to as the distinct subspecies V. v. schrencki, has its own genetic background with multiple migration events and differs from the parapatric subspecies V. v. japonica found in Honshu and Kyushu.     

Body size of the red fox Vulpes vulpes in Spain: the effect of agriculture

The body size of animals is affected by several factors, including ambient temperature and food availability. Ambient temperature is often negatively related to body size (Bergmann's rule) whereas an improved diet, especially during growth, has a positive effect. Animals commensal with man commonly exploit additional food sources (e.g. garbage dumps), thereby increasing their food supply. Using museum material, we studied morphological variation in skull size (and thus body size) among Spanish red foxes. Four measurements were taken of each skull and were related to the habitat from which the foxes were collected (agricultural and non-agricultural), and to latitude as a proxy for ambient temperature. The skull size of foxes collected in agricultural areas during the late 20th Century was significantly larger than that of those from non-agricultural areas, and was negatively related to latitude, thus contradicting Bergmann's rule. We suggest that increased food availability from animal husbandry is the cause for the observed increase in skull size (and thus body size).  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 729–734.     

Fecundity and egg output by Toxocara canis in the red fox, Vulpes vulpes

The role of the red fox Vulpes vulpes in the dissemination of eggs of Toxocara canis into the environment is considered with reference to female worm fecundity and egg output in the faeces of infected foxes collected from four localities in southern England. A significant positive correlation was found between female worm size and the number of eggs in the uterus but there was no significant relationship between T. canis worm numbers and egg output in fox faeces. Reliable estimates of worm burdens in foxes could not, therefore, be determined from faecal egg counts alone. The highest mean egg output of 2145.0 epg recorded from adult foxes indicated that fox cubs are not necessarily the main sources of environmental contamination with T. canis eggs. Saturated magnesium sulphate was found to be a more effective flotation solution than zinc sulphate and sodium chloride for recovering eggs from fox faecal samples.     

准噶尔盆地荒漠区赤狐的食性分析

<正>赤狐(Vulpes vulpes)隶属于哺乳纲、食肉目、犬科、狐属,广泛分布于欧亚大陆、非洲北部和北美大陆,在我国也广布各地(高耀亭等,1987;马世来等,2001)。国内外有关赤狐的研究主要集中在洞穴结构(Nakazono and Ono,1987;贾竞波和萧前柱,1990;贾竞波等,1991;贾竞波和马建章,1992;周文扬和魏万红,1995;张洪海等,1999)和巢域选择等方面(Nakazono and Ono,1987;周文扬和魏万红,1995;张洪海等,1999;Frey and Conover,2006;Keith et al.,2007),而针对赤狐食性的研究主要集中在森林草原或苔原环境,如瑞典(Elmhagen et al.,2002)、立陶宛(Laima,2002)及匈牙利(Lanszki et al.,2006,2007)等。     

Rural populations of the red fox Vulpes vulpes show little evidence of reproductive senescence

The ageing theory predicts fast and early senescence for fast-living species. We investigated whether the pattern of senescence of a medium-sized, fast-living and heavily-culled mammal, the red fox (Vulpes vulpes), fits this theoretical prediction. We used cross-sectional data from a large-scale culling experiment of red fox conducted over six years in five study sites located in two regions of France to explore the age-related variation in reproductive output. We used both placental scars and embryos counts from 755 vixens’ carcasses aged by the tooth cementum method (age range: 1–10), as proxies for litter size. Mean litter size per vixen was 4.7 ± 1.4. Results from Generalized Additive Mixed Models revealed a significant variation of litter size with age. Litter size peaked at age 4 with 5.0 ± 0.2 placental scars and decreased thereafter by 0.5 cubs per year. Interestingly, we found a different age-specific variation when counting embryos which reached a plateau at age 5–6 (5.5 ± 0.2) and decreased slower than placental scars across older ages, pointing out embryo resorption as a potential physiological mechanism of reproductive senescence in the red fox. Contrary to our expectation, reproductive senescence is weak, occurs late in life and takes place at an age reached by less than 11.7% of the population such that very few females exhibit senescence in these heavily culled populations.