Nyctereutes Procyonoides Viverrinus Research Articles

Estimating the impact of sarcoptic mange epidemic on the population size of wild raccoon dogs (Nyctereutes procyonoides) from wildlife rescue data

The impact of infectious diseases on host populations is often not quantified because it is difficult to observe the host population and infectious disease dynamics. To address this problem, we developed a state-space model to simultaneously estimate host population and disease dynamics using wildlife rescue data. Using this model, we aimed to quantify the impact of sarcoptic mange on a Japanese raccoon dog population by estimating the change in their relative population size. We classified the status of rescued raccoon dogs into four categories: i) rescued due to infection with mange, ii) rescued due to traffic accidents without mange, iii) rescued due to traffic accidents with mange, and iv) rescued due to causes other than traffic accidents or mange. We modelled the observation process for each category and fitted the model to the reported number of raccoon dogs rescued between 1990 and 2010 at three wildlife rescue facilities in Kanagawa Prefecture, Japan. The mortality rate induced by mange was estimated to be 1.09 (95% credible interval (CI): 0.47–1.72) per year. The estimated prevalence of sarcoptic mange ranged between 4–80% in the study period. When a substantial prevalence of mange was observed (1995 to 2002), the host population size decreased by 91.2% (95% credible intervals: 86.3–94.7). We show that the impact of infectious disease outbreak on the wildlife population can be estimated from the time-series data of wildlife rescue events due to multiple causes. Our estimates suggest that sarcoptic mange triggered a substantial decrease in the Japanese wild raccoon dog populations.

New host record of Thelazia callipaeda (Nematoda: Spirurida) with a notably wide host range and shared zoonotic lineage in Japan

Thelazia callipaeda (Nematoda: Spirurida: Thelaziidae) parasitizes the eyes of dogs, cats, humans, and various wild mammals, and is transmitted by drosophilid flies. In Japan, T. callipaeda is considered an emerging parasite that has expanded its endemic region northward. However, reports of its detection in mammals other than domestic animals and humans are scarce. This study reports the detection of T. callipaeda in Japanese red fox (Vulpes vulpes japonica), masked palm civet (Paguma larvata), Japanese badger (Meles anakuma), Japanese black bear (Ursus thibetanus japonicus), raccoon (Procyon lotor), Japanese raccoon dog (Nyctereutes viverrinus), domestic dog (Canis lupus familiaris), domestic cat (Felis silvestris catus), and human. Of these, the Japanese red fox, masked palm civet, Japanese badger, and Japanese black bear have been reported as novel host records. Sequence analysis of the cytochrome c oxidase subunit I gene of T. callipaeda revealed two unique lineages specific to Japan, with no regional or host species differences. These results suggest a wide host range for T. callipaeda, highlighting the significant role of wildlife as a reservoir for this parasite in Japan.

Assessing Variation in the Individual-Level Impacts of a Multihost Pathogen

Most pathogens infect more than one host species, and given infection, the individual-level impact they have varies among host species. Nevertheless, variation in individual-level impacts of infection remains poorly characterised. Using the impactful and host-generalist ectoparasitic mite Sarcoptes scabiei (causing sarcoptic mange), we assessed individual-level variation in pathogen impacts by (1) compiling all documented individual-level impacts of S. scabiei across free-living host species, (2) quantifying and ranking S. scabiei impacts among host species, and (3) evaluating factors associated with S. scabiei impacts. We compiled individual-level impacts of S. scabiei infection from 77 host species, spanning 31 different impacts, and totalling 683 individual-level impact descriptions. The most common impacts were those affecting the skin, alopecia (130 descriptions), and hyperkeratosis coverage (106). From these impacts, a standardised metric was generated for each species (average impact score (AIS) with a 0-1 range), as a proxy of pathogen virulence allowing quantitative comparison of S. scabiei impacts among host species while accounting for the variation in the number and types of impacts assessed. The Japanese raccoon dog (Nyctereutes viverrinus) was found to be the most impacted host (AIS 0.899). We applied species inclusion criteria for ranking and found more well-studied species tended to be those impacted more by S. scabiei (26/27 species AIS < 0.5). AIS had relatively weak relationships with predictor variables (methodological, phylogenetic, and geographic). There was a tendency for Diprotodontia, Artiodactyla, and Carnivora to be the most impacted taxa and for research to be focussed in developed regions of the world. This study is the first quantitative assessment of individual-level pathogen impacts of a multihost parasite. The proposed methodology can be applied to other multihost pathogens of public health, animal welfare, and conservation concern and enables further research to address likely causes of variation in pathogen virulence among host species.

Distinctly different gut microbiota in Japanese badgers and Japanese raccoon dogs despite sharing similar food habits and environments

Distinctly different gut microbiota in Japanese badgers and Japanese raccoon dogs despite sharing similar food habits and environments

Bone growth and body weight patterns in juvenile raccoon dogs in Wakayama Prefecture, western Japan

Abstract Information on growth of the Japanese raccoon dog, Nyctereutes procyonoides is limited. We collected 237 juvenile raccoon dogs, road-killed and culled for pest control in Wakayama Prefecture, western Japan from 2002 to 2019. We measured the skull, mandible, femur lengths, and body weights of all specimens and used the body weights of healthy animals (n = 136). We found that these variables increased rapidly up to September and reached maximum values in October. Evidence of dorsal surface roughness of the neurocranium became obvious in October, and up to 35 % of individuals had rough dorsal surfaces of neurocranium in December. Epiphyseal fusion of femurs appeared in September, and 27 % of specimens having fused femurs was recorded in December. This study firstly described the growth patterns of the Japanese raccoon dogs based on a lot of samples.

Molecular characterization of oriental eyeworm (Thelazia callipaeda) detected from raccoon (Procyon lotor) and Japanese raccoon dog (Nyctereutes viverrinus) in Kanto region, Japan

BackgroundThe oriental eyeworm Thelazia callipaeda (Spirurida: Thelaziidae) is an emerging parasitic ocular nematode of carnivores and humans. In domestic animals and humans, the infection causes varying degrees of inflammation and lacrimation, and wild carnivores represent an important reservoir. In this study we examined the infection status and molecular characterization of T. callipaeda in two urban carnivores, raccoons Procyon lotor and wild Japanese raccoon dogs Nyctereutes viverrinus, in the Kanto region of Japan.MethodsFrom January 2020 to December 2021, 193 carcasses including 178 raccoons and 15 raccoon dogs were examined for the presence of worms in the eye. The worms from infected animals (one worm per host) were morphologically identified as T. callipaeda. Worms (1–5 worms per host) were subjected to genetic analysis using mitochondrial cytochrome c oxidase subunit I gene sequences.ResultsThe prevalence of T. callipaeda in raccoons and Japanese raccoon dogs was 20.2% (36/178) and 13.3% (2/15), respectively. The cox1 sequences from 56 worms from 38 animals revealed three haplotypes (h9, h10, and h12). Analysis of multiple worms for five raccoons showed co-infection of two different haplotypes (h9 and h10) in a single host. Comparing our data with published sequences, three sequences obtained from raccoons and raccoon dogs shared the same haplotypes as those reported in humans, dogs, and cats in Japan.ConclusionsOur findings show a high prevalence of T. callipaeda in raccoons, suggesting that this invasive carnivore species serves as an important natural reservoir of T. callipaeda in the Kanto region of Japan, an area with the highest human population of the country.Graphical

Seroprevalence of severe fever with thrombocytopenia syndrome virus in medium-sized wild mammals in Miyazaki, Japan

Severe fever with thrombocytopenia syndrome (SFTS) is a fatal emerging tick-borne zoonotic disease caused by the SFTS virus (SFTSV). SFTSV infection in humans and companion animals is a matter of concern in endemic areas. Various wild animals are involved in the transmission cycle of SFTSV with vector ticks. Because the home range of medium-sized wild mammals commonly overlaps with humans’ living spheres, this study aimed to reveal the endemicity of SFTSV in such mammals. This study investigated the prevalence of antibodies against SFTSV and viral RNA in medium-sized wild mammals in Miyazaki Prefecture, Japan where human cases have been most frequently reported in Japan and performed a phylogenetic analysis to compare the detected SFTSV with those previously reported. Forty-three of 63 (68%) Japanese badgers (Meles anakuma) and 12 of 53 (23%) Japanese raccoon dogs (Nyctereutes procyonoides viverrinus) had antibodies against SFTSV. Japanese marten (n = 1), weasels (n = 4), and Japanese red fox (n = 1) were negative. Two of 63 (3%) badgers tested positive for SFTSV RNA, whereas the other species were negative. Phylogenetic analysis of the partial nucleotide sequence of SFTSV revealed that viral RNA detected from badgers exhibited 99.8% to 100% similarity to SFTSV, as previously reported in humans, cat, and ticks in the study area. This study demonstrated high seropositivity of antibodies in medium-sized wild mammals and suggested that SFTSV could be shared among these mammals, humans, and companion animals in endemic areas.

Antimicrobial resistance in Escherichia coli isolates from Japanese raccoon dogs (Nyctereutes viverrinus) in Kanagawa Prefecture, Japan: Emergence of extended-spectrum cephalosporin-resistant human-related clones.

Introduction. Wild animals are one of the putative reservoirs of antimicrobial-resistant bacteria, but the significance of raccoon dogs remains to be investigated.Hypothesis. Raccoon dogs can be a reservoir of antimicrobial-resistant bacteria.Aim. This study aimed to explore the prevalence of antimicrobial resistance, mainly extended-spectrum cephalosporins resistance, in Escherichia coli isolates from faeces of 80 Japanese raccoon dogs in Kanagawa Prefecture, Japan.Methodology. All of the 80 faecal samples were streaked onto deoxycholate-hydrogen sulfate-lactose (DHL) and cefotaxime (CTX)-supplemented DHL (DHL-CTX) agars. Susceptibilities to ten antimicrobials were determined using the agar dilution method. Additionally, extended-spectrum β-lactamases (ESBLs) and AmpC-type β-lactamases (ABLs) were identified in addition to sequence types (STs), in ESC-resistant isolates by a polymerase chain reaction and sequencing.Results. Out of all the samples, 75 (93.8 %) and 20 (25.0 %) E. coli isolates were isolated by DHL and DHL-CTX agars, respectively. Significantly higher resistance rates to most of the drugs were found in DHL-CTX-derived isolates than DHL-derived isolates (P<0.01). Genetic analysis identified CTX-M-14 (n=6), CTX-M-2 (n=2), CTX-M-1 (n=1) and CTX-M-55 (n=1) as ESBLs, and CMY-2 (n=8) and DHA-1 (n=1) as ABLs in 20 DHL-CTX-derived isolates. Most of the detected STs were related to Japanese humans (i.e. ST10, ST58, ST69, ST131, ST357, ST648 and ST4038). Notably, this is the first report on ST69, ST131, ST155 and ST648, which are well-known international high-risk clones in Japanese raccoon dogs.Conclusion. Our findings underscore the need to understand the significance of raccoon dogs as an antimicrobial-resistant bacteria reservoir using one health approach.

Mapping the Potential Distribution of Ticks in the Western Kanto Region, Japan: Predictions Based on Land-Use, Climate, and Wildlife.

Simple SummaryRecently, the risk of tick-borne diseases (TBD) has drawn increasing attention from a public health perspective. Information about where ticks are distributed is important for the prevention of TBDs. In this study, we used the MaxEnt model to predict the potential distribution of six major tick species out of 16 tick species collected in the Kanto region, the central part of Japan, based on land-use, climate, and wildlife distribution, and to investigate the factors that contribute to each distribution of ticks. The distribution of raccoons contributed to the distribution of five tick species, and forest connectivity was a strong contributor to the distribution of all species.Background: Tick distributions have changed rapidly with changes in human activity, land-use patterns, climate, and wildlife distributions over the last few decades. Methods: To estimate potential distributions of ticks, we conducted a tick survey at 134 locations in western Kanto, Japan. We estimated the potential distributions of six tick species (Amblyomma testudinarium Koch, 1844; Haemaphysalis flava Neumann, 1897; Haemaphysalis kitaokai Hoogstraal, 1969; Haemaphysalis longicornis Neumann, 1901; Haemaphysalis megaspinosa Saito, 1969; and Ixodes ovatus Neumann, 1899) using MaxEnt modeling based on climate patterns, land-use patterns, and the distributions of five common wildlife species: sika deer (Cervus nippon Temminck, 1838), wild boar (Sus scrofa Linnaeus, 1758), raccoon (Procyon lotor Linnaeus, 1758), Japanese raccoon dog (Nyctereutes procyonoides Gray, 1834), and masked palm civet (Paguma larvata C.E.H. Smith, 1827)). Results: We collected 24,546 individuals of four genera and 16 tick species. Our models indicated that forest connectivity contributed to the distributions of six tick species and that raccoon distribution contributed to five tick species. Other than that, sika deer distribution contributed to H. kitaokai, and wild boar distribution, bamboo forest, and warm winter climate contributed specifically to A. testudinarium. Conclusions: Based on these results, the dispersal of some tick species toward residential areas and expanded distributions can be explained by the distribution of raccoons and by forest connectivity.

Development of a rapid scabies immunodiagnostic assay based on transcriptomic analysis of Sarcoptes scabiei var. nyctereutis

Scabies is a highly contagious skin disease caused by the mite Sarcoptes scabiei that affects many mammals. However, the sensitivity of traditional tests for scabies diagnosis in humans is less than 50%. To simplify the diagnosis of scabies, methods that are simple, sensitive, specific, and cost-effective are required. We developed an immunodiagnostic test based on S. scabiei var. nyctereutis RNA-seq data collected from Japanese raccoon dogs with sarcoptic mange. Three candidate antigens—a highly expressed hypothetical protein “QR98_0091190,” another mite allergen known as “SMIPP-Cc,” and an abundant “vitellogenin-like protein”—were evaluated by western-blot analysis. A lateral flow immunoassay, using specific antibodies against the vitellogenin-like protein, successfully detected scabies in the skin flakes of S. scabiei-infected raccoon dogs. This assay can potentially diagnose scabies more accurately in wildlife, as well as in humans.

A mutant gene for albino body color is widespread in natural populations of tanuki (Japanese raccoon dog).

Albino mutants (white coat and red eyes) of tanuki (Nyctereutes procyonoides viverrinus) have been repeatedly found in the Central Alps area of Japan. We recently reported that an albino tanuki from Iida, a city in this area, lacks the third exon of the TYR gene encoding tyrosinase, which is essential for melanin synthesis. The absence of this exon was due to the chromosomal deletion of a complex structure. In the present study, we analyzed TYR of another albino tanuki that was found in Matsusaka, a city located outside the mountainous area. In this animal, the third exon was also lost, and the loss was due to a deletion in which the structure was identical to that of the Iida mutant. Our results indicate, in consideration of the complex structure of the deletion, that the two albino animals inherited a single deletion that arose in their common ancestor. Iida and Matsusaka are approximately 170 km apart. This is, to our knowledge, the first report of an albino mutant gene that is widely distributed in mammalian natural populations. As the origin of this mutation is not known, the distance covered by the mutant gene remains unclear. If we assume that the mutation occurred halfway between Iida and Matsusaka, we can predict the migration distance to be approximately 85 km; however, if the mutation occurred at any other place, a longer distance would be predicted. Natural selection against albino tanuki may be relaxed because of a recent increase in food resources and refuge in urban areas.

Complex intragene deletion leads to oculocutaneous albinism in tanuki (Japanese raccoon dog).

Tanuki (Nyctereutes procyonoides viverrinus), or Japanese raccoon dog, is a canine native to Japan. Tanuki with complete oculocutaneous albinism are relatively frequent in mountainous areas of mainland Japan. Tyrosinase, which is encoded by the TYR gene, is an enzyme essential for the biosynthesis of melanin pigment. We examined the structure and nucleotide sequence of TYR in an albino tanuki and found that the third exon was removed due to a deletion of approximately 11 kb. In addition, two nonsynonymous nucleotide substitutions were found in the fifth exon. These mutations are possible causes of the albino phenotype; however, the order of occurrence is unclear. Even if the 11-kb deletion was not the first of these mutations, it is considered to cause a total loss of the tyrosinase function because the third exon carries codons for one of the two copper-binding sites of tyrosinase and these sites are essential for the enzyme function. Intriguingly, the deletion was not a simple removal of an 11-kb segment: an internal portion was retained as a segment in the reverse orientation. We propose possible formation processes for this mutation that involve multiple DNA scission events, or an inversion followed by a deletion.

Phylogenetic relationships between different raccoon dog (Nyctereutes procyonoides) populations based on four nuclear and Y genes.

The raccoon dog (Nyctereutes procyonoides), endemic to East Asia, is classified as six subspecies according to their geographical distribution including a population introduced to Europe. Studies on phylogenetic relationship or population genetics in both native and introduced areas have been carried out recently. Lately, opinions that Japanese raccoon dogs should be classified as a different species were asserted based on several studies using karyotypes, morphometric characters, mtDNA, and microsatellites analysis. However, no data pertaining to the nuclear DNA (nDNA) or Y chromosome are available. To estimate the relationship among the species using different genes is necessary in understanding of the history of this species. Therefore, we investigated nDNA and Y chromosomes in our study to define relationships: (1) between continental raccoon dog populations, (2) between original and introduced groups, and (3) between continental and Japanese groups. The analysis of four nuclear (CHRNA1, VTN, TRSP, WT1) and ZFY genes indicated that there had been no genetic differentiation among the continental populations. However, significant differences were observed between continental and Japanese raccoon dogs in VTN and ZFY genes implying genetic differentiation has been going between them. To better understand the phylogenetic relationship among raccoon dog populations, further study will be necessary.

MOLECULAR SURVEY OF BARTONELLA ROCHALIMAE IN JAPANESE RACCOON DOGS (NYCTEREUTES PROCYONOIDES VIVERRINUS).

Wild carnivores serve as reservoirs of several zoonotic Bartonella species such as Bartonella henselae, Bartonella vinsonii subsp. berkhoffii, and Bartonella rochalimae. The raccoon dog (Nyctereutes procyonoides viverrinus) is the most common native carnivore in Japan, but epidemiologic studies of Bartonella infections have not been performed in this animal species yet. Here, we report a molecular survey of B. rochalimae prevalence in 619 wild raccoon dogs captured from 2009 to 2017 in western Japan. Bartonella rochalimae DNA was detected in 7.1% (44/619) of the raccoon dogs examined by PCR targeting the rpoB and ssrA genes. All of the sequences obtained were identical in each of the genes. The prevalence of B. rochalimae by sex of the animals was 6.1% (21/344) in male and 8.4% (23/275) in female. The prevalence by year varied from 2% (1/45) in 2011 to 14% (4/28) in 2016. The prevalence (7.9%) of B. rochalimae in the raccoon dogs with sarcoptic mange tended to be higher than the prevalence (4.0%) in the animals without the infestation of mites, although the differences were not significant. Sequence analysis indicated that Japanese raccoon dogs in the area examined were infected with B. rochalimae carrying identical sequences in the rpoB and ssrA genes. In addition, the raccoon dog strain had few sequence variations in both genes compared to other known B. rochalimae strains detected in other parts of the world.

Comparison of feeding habits and habitat use between invasive raccoons and native raccoon dogs in Hokkaido, Japan

BackgroundIn Japan, invasive raccoons cause severe ecological and social problems by transmitting pathogens to humans, livestock, and native species, causing substantial crop damage, and competing with native species. Possible competition between invasive raccoons and native raccoon dogs is of concern in Japan because Japanese raccoon dogs have a limited distribution and are native only to Japan and the two species have similar characteristics. We assessed potential competition between raccoons and raccoon dogs by comparing feeding habits and habitat use.ResultsBoth species were captured in Hokkaido, Japan from 2004 to 2017. More raccoons were captured close to agricultural land at the forest periphery (70.1%, 358/511); conversely, more raccoon dogs were captured in the forest core (74.9%, 253/338). Feeding habits were then examined by fecal analysis and stable isotope analyses. Fecal analysis revealed both species to be opportunistic omnivores that consumed easily found food items. However, raccoon feces contained more crops, whereas raccoon dog feces contained more insects, reflecting the different locations in which the species were trapped. Moreover, stable isotope ratios were significantly higher in raccoons than raccoon dogs (Corn has the highest carbon stable isotope (δ13C) value, and amphibians and reptiles are high in nitrogen stable isotope (δ15N); forest resources such as insects and wild fruits are low in δ13C and δ15N).ConclusionsWe conclude that both species ate similar food types, but their food preferences appeared to differ. Raccoon and raccoon dog habitat use also differed, possibly because the two species inhabited areas where they could easily obtain their preferred foods. Therefore, the current feeding habits and habitat use of raccoons do not appear to overlap sufficiently with those of raccoon dogs to impact the latter. The results of this study, particularly the stable isotope data, may provide a useful precedent for future studies of competition in medium-sized mammals, particularly canids.

The complete mitochondrial genome of Sarcoptes scabiei var. nyctereutis from the Japanese raccoon dog: Prediction and detection of two transfer RNAs (tRNA-A and tRNA-Y)

Sarcoptes scabiei (Acari: Sarcoptidae) causes a common contagious skin disease that affects many mammals. Here, the complete mitochondrial genome of a mite, S. scabiei var. nyctereutis, from Japanese wild raccoon dogs was analyzed. The 13,837bp circular genome contained 13 protein-coding genes, two rRNA genes, and 22 tRNA genes. For the first time, two tRNAs (alanine and tyrosine), that were thought to be absent in scabies mites from other animals, were predicted to have short, non-cloverleaf structures by in silico annotation and detected by RT-PCR, sequencing, and northern analysis. The mitochondrial genome structure of S. scabiei is similar to that of Psoroptes cuniculi and Dermatophagoides farinae. While small and unusual tRNA genes seem to be common among acariform mites, further experimental evidence for their presence is needed. Furthermore, through an analysis of the cox1 gene, we have provided new evidence to confirm the transmission of this mite between different animal hosts.

Home range of raccoon dogs in an urban green area of Tokyo, Japan

The raccoon dog (Nyctereutes procyonoides viverrinus) has recently become common in urban environments in Japan. We predicted that, like other carnivores adapted to urban environments, raccoon dogs in urban areas should have smaller home ranges than those in rural areas. We investigated the size of home ranges of raccoon dogs in the Akasaka Imperial Grounds, a 51-ha green area in central Tokyo. Between August 2012 and August 2014, 7 adult males and 4 adult females were radiotracked. Mean (± SD) home range size of these 11 raccoon dogs (100% minimum convex polygon = 17.6 ± 13.0 ha; 95% fixed kernel = 8.3 ± 5.7 ha) was smaller than that of raccoon dogs in rural areas obtained in previous studies, and core areas (75% local convex hull) averaged 3.7 ± 4.1 (SD) ha. We detected no seasonal changes in home range size. These results were consistent with the notion that urban carnivores typically have small home ranges. The small home range size seems to be explained by abundance of food resources, restricted environment, and the high population density of raccoon dogs in the urban green area.

Cytogenetic Profile of Rajapalayam Dog Breed of Southern India

Rajapalayam, an important dog breed of southern India which are maintained for guarding of farm houses and protection from wild animals. The aim of the present investigation is to study the karyology of this important dog population for cytological profiling. Metaphase plates were prepared after culturing of lymphocytes isolated from heparinized blood collected from animals of both the sexes. Giemsa banding, centromeric index, arm ratio and relative length were estimated through standard protocol. The cytogenetic profile of Rajapalayam dog is different from that of Chinese Raccoon and Japanese Raccoon dogs which belongs to Canidae family with a basic chromosome number of 78 without B chromosome. The X chromosomes are longer in bitches than that of in dogs. Giemsa banding analysis revealed higher number of bands (272) distributed among the 38 chromosome in Indian dog breed as compared to that Chinese Raccoon dog. The results of the present study gave insight knowledge to the researchers, dog breeders and kennel clubs about the karyology of Indian dog breeds and to know about any chromosomal abnormalities which may leads to fertility, growth and phenotypic abnormality related problems in this dog breed.

Cytogenetic Profile of Rajapalayam Dog Breed of Southern India

Rajapalayam, an important dog breed of southern India which are maintained for guarding of farm houses and protection from wild animals. The aim of the present investigation is to study the karyology of this important dog population for cytological profiling. Metaphase plates were prepared after culturing of lymphocytes isolated from heparinized blood collected from animals of both the sexes. Giemsa banding, centromeric index, arm ratio and relative length were estimated through standard protocol. The cytogenetic profile of Rajapalayam dog is different from that of Chinese Raccoon and Japanese Raccoon dogs which belongs to Canidae family with a basic chromosome number of 78 without B chromosome. The X chromosomes are longer in bitches than that of in dogs. Giemsa banding analysis revealed higher number of bands (272) distributed among the 38 chromosome in Indian dog breed as compared to that Chinese Raccoon dog. The results of the present study gave insight knowledge to the researchers, dog breeders and kennel clubs about the karyology of Indian dog breeds and to know about any chromosomal abnormalities which may leads to fertility, growth and phenotypic abnormality related problems in this dog breed.

Estimation of diet in extinct raccoon dog species by the molar ratio method

AbstractEstimation of the dietary habits of extinct species using morphological traits has been attempted in numerous studies; however, previous methods have encountered several difficulties, such as requiring specialized equipment. In this study, we describe an easy quantitative method for estimating the dietary habits, and apply it to extinct raccoon dogs (Nyctereutes) species (Carnivora, Mammalia). The method is based on the lower molar ratios (M2/M1 size) that reflect the species diet (carnivorous and omnivorous tendencies) in Canidae. Among the species statistically compared, Nyctereutes sinensis showed a lower M2/M1 score similar to that of Nyctereutes procyonoides albus (Hokkaido, Japan), whereas Nyctereutes tingi had a higher M2/M1 score similar to that of Nyctereutes procyonoides viverrinus (Honshu and Kyushu, Japan). These scores suggest that the diets of N. sinensis and N. tingi were similar to those of N. p. albus (relatively carnivorous) and N. p. viverrinus (relatively omnivorous), respectively. Other extinct raccoon dogs also showed varied M2/M1 score, suggesting dietary difference. These results suggest that raccoon dogs underwent dietary transitions or exhibited dietary plasticity during evolution, while their range of diets might have remained the same as those of different populations of extant species Nyctereutes procyonoides.