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PubMed2002

Do helminths increase the vulnerability of released pheasants to fox predation?

The success of ring-necked pheasant (Phasianus colchicus) restocking in Asturias, northern Spain was assessed, and the role of parasites and predators in the mortality of released birds was studied. The experimental release of 56 radio-tagged pheasants showed that 98% of birds died within 12 days. As soon as 72 h after release, 67.5% of males and 55.0% of females were found dead. Foxes (Vulpes vulpes) killed 63% of the birds. The survival of those birds killed by foxes was lower than for birds which died due to other causes, and pheasants depositing eggs of the nematode Eucoleus contortus (Creplin, 1839) survived less than those apparently non-parasitized. No impact of the parasite on the pheasants' condition was found, but foxes preyed upon parasitized birds more than expected by random. The results suggest that: (i) the current pheasant releases in this area are unsuccessful and need to be improved; (ii) this is mainly due to intense predation by red foxes; and (iii) parasites could have some influence on the predation of released birds by foxes. However, the way parasites affect pheasant vulnerability remains unclear.

Animal Husbandry↗
PubMed1983

The susceptibility of the European red fox (Vulpes vulpes) to infection with Echinococcus granulosus of Australian sheep origin.

A detailed comparative study was made of the development of Echinococcus granulosus of Australia sheep origin in European red foxes (Vulpes vulpes) and dogs. No significant differences in growth, segmentation or maturation of the parasite between dogs or foxes was found, although worm burdens were slightly lower in foxes than in dogs. It is concluded that although the role of foxes in the epidemiology of hydatidosis in Australia may not be significant, foxes should nevertheless be regarded as potential definitive hosts of the Australian strains of E. granulosus.

Animals↗
PubMedDate not supplied

Energy expenditure and water flux of Rüppell's foxes in Saudi Arabia.

Scattered populations of Rüppell's foxes (Vulpes rueppelli) occur across the deserts of northern Africa and Arabia. Little is known about the biology of these canids, especially the physiological mechanisms that contribute to their ability to live in such harsh environments. For individuals from Saudi Arabia, we tested the hypotheses that Rüppell's foxes have a reduced basal metabolic rate and total evaporative water loss (TEWL), parameters measured in the laboratory, and a reduced field metabolic rate (FMR) and water flux when free-living. Under basal conditions in the laboratory, males, which averaged 1,858 g in body mass, had an oxygen consumption of 914.9 mL O(2)/h, whereas females, which weighed on average 1,233 g, consumed 682.9 mL O(2)/h; rates of oxygen consumption translated to 441.4 kJ/d and 329.4 kJ/d, respectively. TEWL averaged 52.6 g H(2)O/d for males and 47.5 g H(2)O/d for females. We found no evidence that basal metabolism is reduced in Rüppell's foxes, but their TEWL was remarkably low: 50.9% of allometric prediction for males and 64.5% for females. In the wild during winter, males expended energy at a rate of 1,306.5 kJ/d, whereas females had an expenditure of 722.8 kJ/d. Analysis of covariance with FMR as the dependent variable, sex as a fixed factor, and body mass as a covariate showed no statistical difference in FMR between sexes. Water flux did not differ significantly between sexes and averaged 123 mL H(2)O/d, a value 30% lower than the kit fox from the deserts of southwestern North America. FMR was positively related to nocturnal activity levels as FMR (kJ/d) = -2,900.1+55.5 (% of time moving). The water content of prey items varied between 1.9 and 4.1 g H(2)O/g dry matter consumed. Based on these values and knowledge of their diet, we calculated that foxes captured about one rodent and a variety of anthropods per night of foraging.

Animals↗
PubMed2004

Patterns histopathologic of Fox-Fordyce disease.

Fox-Fordyce disease is an uncommon condition that is biopsied even less commonly. Since the publication of Shelley and Levy, in 1956, the disease is regarded widely to be "apocrine miliaria", an analogue of eccrine miliaria. Histopathologically, an "intraepidermal sweat retention vesicle" is considered the only feature diagnostic of the condition. In this article, the entire literature devoted to the subject and reviewed features clinically and histopathologically as they were presented in those publications. Furthermore, observations in sections of tissue cut from 8 biopsy specimens taken from 4 patients with Fox-Fordyce disease are presented including correlation clinicopathologic. Changes histopathologically in Fox-Fordyce disease vary greatly. Apart from findings described previously as being typical (e.g., dilation, hyperkeratosis, and spongiosis of infundibula), there were vacuolar alteration at the dermo-epithelial junction of infundibula, dyskeratotic cells scattered in infundibula, and parakeratosis in the manner of cornoid lamellation within an orthokeratotic plug filling a dilated infundibulum. Infundibula and apocrine ducts were surrounded by numerous foamy macrophages. Despite that variation of features histopathologically, the appearance clinically, was similar in all patients, namely small infundibulocentric papules, sometimes with a keratotic plug in the center of it, and sometimes with a yellow cast. In conclusion, current concept of Fox-Fordyce disease is too restricted. All the different patterns histopathologically observed by us are manifestations of one single pathologic process named for Fox and Fordyce.

Dermatology↗
PubMed1975

Xenogeneic skin and kidney transplants in a closely related canine system, fox-dog.

Fox kidney and skin grafts were transplanted into dog recipients. Fox kidneys, transplanted en bloc into untreated dogs, survived 6.2 +/- 0.4 days. The skin transplants survived 5.9 +/- 1.4 days. The grafted kidneys showed almost normal function before rejection. Both skin and kidney rejection were mediated through a cellular mechansim. Performed natural antibodies against donor tissue were not present in the serum of the recipients. These results combined with absorption studies suggested a close relationship between fox and dog, but different number and morphology of chromosomes, immunoelectrophoretic patterns of serum proteins, and disparities of the transplantation antigens proved that the fox is a species quite separate from the dog. It was concluded that the fox-dog system, with its similarity to the chimpanzeeman relationship, offers a unique model to study clinically applicable methods of managing xenografts between closely related species.

Animals↗
PubMed2006

Assessing reliability of microsatellite genotypes from kit fox faecal samples using genetic and GIS analyses.

Noninvasive faecal DNA sampling has the potential to provide a wealth of information necessary for monitoring and managing endangered species while eliminating the need to capture, handle or observe rare individuals. However, scoring problems, and subsequent genotyping errors, associated with this monitoring method remain a great concern as they can lead to misidentification of individuals and biased estimates. We examined a kit fox scat data set (353 scats; 80 genotypes) for genotyping errors using both genetic and GIS analyses, and evaluated the feasibility of combining both approaches to assess reliability of the faecal DNA results. We further checked the appropriateness of using faecal genotypes to study kit fox populations by describing information about foxes that we could deduce from the 'acceptable' scat genotypes, and comparing it to information gathered with traditional field techniques. Overall, genetic tests indicated that our data set had a low rate of genotyping error. Furthermore, examination of distributions of scat locations confirmed our data set was relatively error free. We found that analysing information on sex primer consistency and scat locations provided a useful assessment of scat genotype error, and greatly limited the amount of additional laboratory work that was needed to identify potentially 'false' scores. 'Acceptable' scat genotypes revealed information on sex ratio, relatedness, fox movement patterns, latrine use, and size of home range. Results from genetic and field data were consistent, supporting the conclusion that our data set had a very low rate of genotyping error and that this noninvasive method is a reliable approach for monitoring kit foxes.

Animals↗
PubMed1994

Control of rabies in foxes: what are the appropriate measures?

Until recent years, the depopulation of reservoir species was the only feasible measure to break the transmission chain of rabies in wildlife. In Europe at the beginning of this century, when applied with compulsory muzzling and restrictions on movement, dog depopulation was shown to be effective before any large scale vaccination of dogs. Some examples of the success of the application of depopulation measures on wild carnivores in the past are described. But in the case of enzootics of rabies in the fox, the control measures applied to fox populations sometimes decreased the prevalence or postponed the invasion of an area but did not free or protect an area permanently. Some examples taken from France illustrate the difficulties of drawing clear conclusions from the results of control measures. Conversely, the oral vaccination of foxes was demonstrably successful in preventing the spread of rabies. However, mathematical modelling, historical considerations and first observations in areas in which foxes have been vaccinated strongly suggest that the 'traditional' methods of controlling fox populations, at least by hunting, should not be restricted because they complement the effects of vaccination.

Animals↗
PubMed1983

Studies on pathogenic, immunogenic, and protective efficiency of fox rabies virus before and after adaptation to cell culture: application to vaccination against rabies.

Rabies virus from the submandibular salivary gland of a naturally infected fox was adapted to growth in BHK-21 cells. The pathogenicity of the original isolate and the cell culture adapted virus were compared by the intramuscular and oral routes in mice and foxes. Animals surviving exposure were tested for serum rabies antibodies (immunogenic efficiency) and for their ability to survive a second challenge with rabies virus (protective efficiency). In mice, ratios between lethal and protective doses of the two strains via the oral or muscular route were similar. In foxes, however, pathogenic efficiency was modified after cell culture adaptation, although good immunogenic and protective efficiency was maintained. Inoculation via the oral route resulted in lethal infection with the wild-type strain and survival (with some subsequent immunity) with the cell-adapted strain. Via the intramuscular route, foxes given high doses of cell culture adapted virus survived whereas several foxes given lower doses died and virus could not be reisolated. It is concluded that safety testing of modified strains should be done with different dilutions of virus in the target species. "Autosterilizing" infections may result in erroneous diagnosis.

Adaptation, Physiological↗
PubMed2005

Distribution of Crenosoma vulpis and Eucoleus aerophilus in the lung of free-ranging red foxes (Vulpes vulpes).

Crenosoma vulpis and Eucoleus aerophilus are nematode parasites that can cause verminous pneumonia in wild carnivores. There is a paucity of information regarding the distribution of parasites in the lungs and the relationship between histopathological and parasitological diagnoses in naturally infected foxes. The objectives of this study were: first, to study the lobar and airway distribution of C. vulpis and E. aerophilus in wild red foxes and second, to investigate the relationship between fecal and histopathological diagnoses. Samples from 6 sites of the lung and fecal contents were obtained from 51 wild foxes in Prince Edward Island. By fecal examination, 78.4% of wild foxes tested positive for C. vulpis and 68.6% for E. aerophilus. In contrast, 66.6% and 49% of foxes had histopathological evidence of C. vulpis and E. aerophilus in the lungs, respectively. Anatomically, C. vulpis was observed in the small bronchi and bronchioles of all pulmonary lobes whereas E. aerophilus was restricted to the large bronchi and the caudal lobes. Affected airways exhibited severe epithelial glandular hyperplasia and bronchiolar mucous metaplasia. It was concluded that C. vulpis is widely distributed in airways of all pulmonary lobes, whereas E. aerophilus is mainly restricted to the bronchi of caudal lobes. Also, this study showed that histological examination of lung underestimates the infection with E. aerophilus.

Animals↗
PubMed2003

Age- and sex-dependent distribution of persistent organochlorine pollutants in urban foxes.

The colonization of urban and suburban habitats by red foxes (Vulpes vulpes) provides a novel sentinel species to monitor the spread of anthropogenic pollutants in densely populated human settlements. Here, red foxes were collected in the municipal territory of Zürich, Switzerland, and their perirenal adipose tissue was examined for persistent organochlorine residues. This pilot study revealed an unexpected pattern of contamination by polychlorinated biphenyls (PCBs), with significantly higher levels of the predominant congeners PCB-138, PCB-153, and PCB-180 in juvenile foxes relative to adult animals. Further data analysis demonstrated that the observed difference was attributable to an age-dependent reduction of PCB concentrations in females, whereas male foxes retained approximately the same PCB burden throughout their life span. A similar sex-related bias between population members has been observed, primarily in marine mammals. Interestingly, the reduction of organochlorine contents with progressive age is reminiscent of human studies, where an extensive maternal transfer of xenobiotics to the offspring has been shown to result in increased exposure levels of infants relative to adults. To our knowledge, this is the first example of an urban wildlife species that faithfully reflects the dynamic distribution of toxic contaminants in the corresponding human population. Suburban and urban foxes occupy habitats in close proximity to humans, depend on anthropogenic food supplies, are relatively long-lived and readily available for sampling, can be easily aged and sexed, have a limited home range, and, therefore, meet several important requirements to serve as a surrogate species for the assessment of toxic health hazards.

Adipose Tissue↗
PubMedDate not supplied

Effects of seasonality and fasting on the body mass and plasma growth hormone concentrations of the raccoon dog (Nyctereutes procyonoides) and the blue fox (Alopex lagopus).

Growth hormone (GH) promotes growth and endochondral ossification, but it is also important in the response to fasting due to its effects of increasing gluconeogenesis and lipolysis. In this study eleven raccoon dogs and blue foxes were followed for six months and their body mass and GH levels were measured. In November half of the animals of both species were put to a three-week fast. There were no significant differences in the GH levels between the animals of different ages and the subadults and adults both had quite low GH levels in the summer. Fasting had no effect on the GH levels of the raccoon dogs, but the fasting blue foxes had lower GH concentrations than the controls in Nov 16th. The control blue foxes experienced a significant increase in the GH levels in early November and the fasting blue foxes in late November. The GH concentrations of all the raccoon dogs rose in early December. As fasting did not cause an elevation in the GH levels but the concentrations increased with decreasing temperature and shortening daylength, the autumnal GH secretion of these species could be regulated by endogenous seasonal rhythms entrained by exogenous Zeitgebers such as temperature or photoperiod. The autumnal increase of GH levels contributes to the response to fasting as an adaptation to survive the winter months with inadequate nutrition. The raccoon dog which spends the coldest part of the winter in winter sleep seems to be better adapted to a total fast than the actively wintering blue fox.

Animals↗
PubMed1987

Hematologic values of the endangered San Joaquin kit fox, Vulpes macrotis mutica.

Between 1981 and 1982 blood samples were collected from 64 adult San Joaquin kit foxes, Vulpes macrotis mutica, in western Kern County, California. The goal of the study was to establish normal blood values for this endangered species, and to determine whether changes in them could be used to assess the possible effects of petroleum developments on these foxes. None of the values differed significantly between the sexes, or between foxes sampled in developed habitats compared with foxes sampled in undisturbed habitats. Mean values of Hb, MCH, MCHC, and WBC counts differed significantly between summer and winter. Average hematological characteristics were: RBC, 8.4 X 10(6)/microliter; Hb, 14.5 g/dl (summer), 15.6 g/dl (winter); PCV, 46.9%; MCV, 56.3 fl; MCH, 17.8 pg (summer), 18.4 pg (winter); MCHC, 31.2 g/dl (summer), 33.2 g/dl (winter); and WBC, 6,200/microliter (summer), 7,500/microliter (winter). Comparisons of hematological data for kit foxes, coyotes (Canis latrans), and wolves (Canis lupus) confirmed a previously published observation that within mammalian families RBC counts are correlated inversely with body weight, and that MCV is correlated directly with body weight.

Animals↗
PubMed1993

The prevalence of Trichinella sp. in Arctic foxes (Alopex lagopus) in Svalbard.

The prevalence of Trichinella sp. in arctic foxes (Alopex lagopus) from Svalbard was studied from 1983 to 1989. Diaphragms of 697 foxes were examined for larvae; 59 foxes (8.5%) were infected. The prevalence of Trichinella sp. increased from 4% in juveniles to 36% in foxes aged more than 6 years of age. There were no significant correlations when condition and body weight each were correlated to the occurrence and number of larvae of Trichinella sp. More foxes were infected in the northern than in the central part of Svalbard. There were only minor differences in prevalence among years.

Age Factors↗
PubMed2002

Immobilization of swift foxes with ketamine hydrochloride-xylazine hydrochloride.

There is an increasing need to develop field immobilization techniques that allow researchers to handle safely swift foxes (Vulpes velox) with minimal risk of stress or injury. We immobilized captive swift foxes to determine the safety and effectiveness of ketamine hydrochloride and xylazine hydrochloride at different dosages. We attempted to determine appropriate dosages to immobilize swift foxes for an adequate field-handling period based on three anesthesia intervals (induction period, immobilization period, and recovery period) and physiologic responses (rectal temperature, respiration rate, and heart rate). Between October 1998-July 1999, we conducted four trials, evaluating three different dosage ratios of ketamine and xylazine (2.27:1.2, 5.68:1.2, and 11.4:1.2 mg/kg ketamine:mg/kg xylazine, respectively), followed by a fourth trial with a higher dosage at the median ratio (11.4 mg/kg ketamine: 2.4 mg/kg xylazine). We found little difference in induction and recovery periods among trials 1-3, but immobilization time increased with increasing dosage (P < 0.08). Both the immobilization period and recovery period increased in trial 4 compared with trials 1-3 (P < or = 0.03). There was a high variation in responses of individual foxes across trials, making it difficult to identify an appropriate dosage for field handling. Heart rate and respiration rates were depressed but all physiologic measures remained within normal parameters established for domestic canids. We recommend a dosage ratio of 10 mg/kg ketamine to 1 mg/kg xylazine to immobilize swift foxes for field handling.

Anesthetics, Dissociative↗
PubMed2004

Oral vaccination of captive arctic foxes with lyophilized SAG2 rabies vaccine.

Arctic foxes (Alopex lagopus) were immunized with lyophilized SAG2 oral rabies vaccine. The effectiveness of this vaccine was determined by serologic response and survival to challenge by rabies virus isolated from a red fox from Alaska (USA). No vaccine virus was found in saliva 1-72 hr after ingestion. At 2 wk after vaccination, all foxes had seroconverted, with rabies virus neutralizing antibody levels of 0.2-3.1 IU ml(-1). All vaccinated foxes survived to week 17 after challenge, and hippocampus, pons, and cerebellum were free of rabies virus as determined by direct immunofluorescence testing after death. One of four nonvaccinated foxes survived challenge and was free of rabies virus in neural tissue, and no rabies virus neutralizing antibody was detected in blood. Our results suggest that the lyophilized SAG2 oral rabies vaccine could be effective in arctic and subarctic regions, where freezing air and ground temperatures probably would not reduce its immunogenicity.

Administration, Oral↗
PubMed2004

Occurrence of Helicobacter Infection in the gastric mucosa of free-living red foxes (Vulpes vulpes).

We studied gastric Helicobacter spp. in five red foxes (Vulpes vulpes). Samples of stomach from the cardia, corpus, pyloric antrum, and duodenum were subjected to histopathologic, immunohistochemical, and transmission electron microscopy (TEM) examination for the presence of Helicobacter and gastritis. All foxes had gastric Helicobacter-like organisms (GHLOs) on examination by light microscopy and TEM. Gastric Helicobacter-like organisms were present in all areas of the stomachs. Chronic mild or moderate gastric inflammation was associated with infection by GHLOs in one or more regions of the stomach, but there was no correlation between inflammation and infection. It is not clear whether the organisms were causing the minimal histologic lesions observed, but the gastric mucosa of free-living foxes appears to be commonly colonized with GHLOs. The frequent colonization of free-living foxes with distinct GHLOs possibly reflects their special characteristic in feeding and/or social behavior or the potential commensal nature of the bacteria in free-ranging foxes.

Animals↗
PubMed1976

Consideration of an association between geographic distribution of caves and occurrence of rabies in foxes.

Establishing a causative relationship for the association between geographic distribution of caves and the occurrence of rabies in foxes in the United States will require the demonstration of a plausible biological mechanism and proof from carefully designed epidemiologic studies. Considerable data implying biological plausibility exists in the form of rabies as an enzootic disease in bats, bat predation by ground animals, bat migratory patterns, and several possible virus transmission routes to the fox. Further data showing development of rabies in the fox following appropriate bat contact are needed. Evidence leading to the acceptability of a causal relationship should distinguish between spurious, causal, and indirect hypotheses. An alternative hypothesis is whether cave areas are superior fox habitats and harbor far greater populations of foxes than do noncave areas.

Animals↗
PubMed2001

Prevalence of species of Toxocara in dogs, cats and red foxes from the Poznan region, Poland.

The prevalence of toxocariasis was evaluated for 445 dogs, 105 cats and 92 foxes from the Poznan region during 1997-1998. Forty one cats were infected (39%), 140 dogs (32%) and 15 red foxes (16%). Toxocara canis was found most frequently in puppies up to 3 months old (58%) and T. cati in kittens 4-6 months old (64%). Toxocariasis was much more prevalent amongst adult foxes (14%) than adult dogs (3%). In contrast to cats, female dogs and foxes were less infected than males. The present study suggests that cats may constitute an underestimated risk of transmission of Toxocara spp. to humans and the progressive synatropization of red foxes may also increase the sources of environmental contamination with Toxocara eggs.

Age Factors↗