The flea epifauna of a suburban fox (Vulpes vulpes) population

Five hundred and thirteen fleas, of eight different species, were collected from a sample of 252 foxes killed in suburban London. 25–8% of foxes carried fleas, with a mean of 204 fleas per fox. Levels of infestation of male and female hosts did not differ significantly. Possible sources of the fleas infesting foxes are discussed with respect to their seasonal occurrence and fox prey composition. No evidence was found to support the suggestion that foxes obtain the majority of their fleas from prey items, although occasional heavy infestations of some flea species were probably derived from recent meals. Although Pulex irritans, Paraceras m. melis and Ctenocephalides canis , which contributed 35 % of the flea epifauna, could be considered parasitic on the fox, it seems probable that foxes pick up the majority of their fleas from the habitat through which they move. Thus, two particularly heavily infested categories of foxes were found: (1) juveniles during July-September, their fleas probably being accumulated during exploratory and play activities, and (2) all animals during the period October-December.     

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.     

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.     

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.     

Successful embryo transfer in the silver fox (Vulpes vulpes)

Surgical embryo transfer in the silver fox was investigated as part of a larger project concerning the conservation of endangered canine species using modern artificial reproduction techniques with the farmed fox as a model. The animals were chosen on the basis of synchrony in natural oestrus. The timing of ovulation and artificial insemination was determined by measuring electrical resistance in the vagina. Twenty-nine embryos were flushed from eight humanely killed donor females and transferred surgically into the uteri of eight recipients. One recipient female gave birth to two male pups 47 days after the transfer of four expanded blastocysts and one embryo at the 16-cell stage derived from a donor female flushed 10 days after artificial insemination.     

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.     

Responses of small mammals to Red fox (Vulpes vulpes) odour

This paper describes the responses of three species of rodents (Apodemus sylvaticus, Microtus agrestis and Clethrionomys glareolus) and a shrew (Sore.x araneus) to traps tainted with the faecal odour of a predator, the Red fox. The rodents generally avoided traps bearing fox odour, but readily entered traps marked with rodent odour, whereas shrews entered all traps equally. Among the rodents, avoidance of fox odour was strongest in male A. sylvaticus and C. glareolus and least in M. agrestis and female A. sylvaticus . Fox droppings were found principally along paths and in open habitats where, of the rodents mentioned, they were most likely to be encountered by A. sylvaticus . It was suggested that avoidance of fox faecal and urinary odours in this species, especially by the active males, would reduce the time spent in areas frequented by foxes, and hence reduce the chance of encountering the predator itself. In contrast, M. agresis would seldom encounter fox droppings in its sub-surface runways, so avoidance of fox faecal odour would do little to reduce its chance of encountering the predator. Avoidance by the rodents of the faecal odour of badger, a predator not present in the study areas, was only slightly less marked than their avoidance of fox faecal odour. It was postulated that similar chemicals eliciting avoidance in rodents may commonly occur in the faeces and urine of carnivores.     

Seasonal and age changes in the thymus gland of the Red fox, Vulpes vulpes,

Seasonal and age changes in thymus weight and histological structure were examined in the Red fox ( Vulpes vulpes ). Growth in the fox thymus slowed down after birth compared with the last third of foetal existence, but the gland still grew rapidly to reach a peak first year weight when the cubs were 20 weeks of age. From this point the thymus in both sexes decreased markedly in weight to reach a low point by the beginning of the first breeding season. During this involution lobule structure broke down and adipose tissue and connective tissue was laid down in the gland. Recovery of the thymus towards the second year weight maximum was accompanied by the regaining of lobule structure and the gland resembled that of the juvenile again. The male thymus increased in weight from the middle of the mating season, but recovery in the female thymus was delayed until the end of lactation. Involution occurred prior to the second breeding season. Thereafter, the gland never attained the high weights seen in the first two years of life, but histological changes still occurred even in old animals. The thymus gland of animals infected with sarcoptic mange is described.     

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.     

Photoperiodic regulation of reproduction in the male silver fox (Vulpes vulpes)

Six silver fox males were exposed to short days (6L:18D) from February, when the testes were fully developed, until June 1986 (Group 6L). Eight males maintained in natural daylight served as controls (Group N). Histological sections from the testes of 2 males in Group 6L killed in June indicated full spermatogenic activity. Three blue fox vixens inseminated the following year with semen collected and frozen in June from 3 males in Group 6L failed to produce litters. One possible explanation for the reproductive failures could have been that the high environmental temperatures in June influenced semen quality. There was no significant difference (P greater than 0.05) in LH release in response to GnRH stimulation in June, but testosterone response to LH release was significantly higher (P less than 0.01) in animals subjected to a restricted photoperiod, demonstrating that testicular testosterone production was maintained longer than in control animals. Two males in Group 6L were retained in 6L:18D from June until December 1986 and then exposed to natural daylight until the end of the study in May 1987 (Group 6L:6L:N). These males started to shed their winter coat and showed clinical signs of testicular regression in December, i.e. after approximately 11 months exposure to 6L:18D. The 2 remaining males in Group 6L were moved to cages with natural daylight in June 1986, where they were kept until the end of the experiment (Group 6L: N:N). These males displayed testicular regression soon after the change in photoperiod but maintained their capacity for testicular redevelopment during the following breeding season.(ABSTRACT TRUNCATED AT 250 WORDS)