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Prion diseases, or transmissible spongiform encephalopathies (TSEs), are a group of invariably fatal neurodegenerative disorders. One of the candidate genes involved in prion diseases is the shadow of the prion protein (SPRN) gene. Raccoon dogs, a canid, are considered to be a prion disease-resistant species. To date, the genetic polymorphisms of the SPRN gene and the predicted protein structure of the shadow of prion protein (Sho) have not been explored in raccoon dogs. SPRN was amplified using polymerase chain reaction (PCR). We also investigated the genetic polymorphisms of SPRN by analyzing the frequencies of genotypes, alleles, and haplotypes, as well as the linkage disequilibrium among the identified genetic variations. In addition, in silico analysis with MutPred-Indel was performed to predict the pathogenicity of insertion/deletion polymorphisms. Predicted 3D structures were analyzed by the Alphafold2. We found a total of two novel synonymous single nucleotide polymorphisms and three insertion/deletion polymorphisms. In addition, the 3D structure of the Sho protein in raccoon dogs was predicted to resemble that of the Sho protein in dogs. This is the first study regarding the genetic and structural characteristics of the raccoon dog SPRN gene.

Cryptosporidium spp. and Giardia duodenalis are zoonotic food- and water-borne protozoa of veterinary importance. They are one of the main causes of diarrhea in domestic dogs (Canis familiaris). Wild canids, such as red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides), can act as natural reservoirs for these parasites. The aim of this study was to estimate the prevalence of these pathogens and analyze possible factors that may affect the infection in wild and domestic canids. A total of 373 domestic dog, 219 red fox, and 78 raccoon dog fecal samples were collected and tested for Cryptosporidium spp. and G. duodenalis presence with direct immunofluorescent staining. The dog owners filled a questionnaire on the dog’s habits and lifestyle to identify and analyze potential factors that may affect the occurrence of these parasites in dogs. Cryptosporidium spp. were found in 16.3%, 28.3%, and 28.2% and G. duodenalis in 0.7%, 27.4%, and 30.8% of the examined dogs, red foxes, and raccoon dogs, respectively. The highest prevalence was observed in puppies—15.4% and 18.5% for Cryptosporidium spp. and G. duodenalis, respectively. In all three canid species, infection with Cryptosporidium increases the risk of co-infection with Giardia and vice versa.

Raccoon dogs (Nyctereutes procyonoides) and raccoons (Procyon lotor) are invasive alien species originating from East Asia and North America, respectively. They are discussed as vectors and reservoirs for various infectious diseases, including vector-borne and zoonotic pathogens, and are therefore a potential threat to human and domestic animal health, as well as to biodiversity and conservation. In the years 2021 and 2022, 110 raccoon dogs (Nyctereutes procyonoides) and 30 raccoons (Procyon lotor) were screened via qPCR for the presence of Leptospira spp., Rickettsia spp. and Borreliella spp. in the German federal state of Schleswig-Holstein as part of a health and risk assessment study. Borreliella spp. were confirmed in one raccoon dog and one raccoon, identified as Borreliella afzelii in the raccoon. Leptospira spp. were found in 21 (19.44%) raccoon dogs and 2 (6.90%) raccoons. In five raccoon dogs, Leptospira spp. were identified as Leptospira borgpetersenii, Leptospira kirschneri and Leptospira interrogans.

The raccoon dog (Nyctereutes procyonoides) is a typical omnivore possessing wide dietary adaptability and tolerance to rough feeding, which may be attributed to its intestinal microbiota. The study aimed to investigate the effect of dietary alfalfa meal levels on the growth performance, nutrient apparent digestibility, serum parameters, and intestinal microbiota of raccoon dogs. Sixty raccoon dogs were randomly divided into four dietary treatments containing 0% (AM0), 5% (AM5), 10% (AM10), and 15% (AM15) alfalfa meal for a 60-day experiment. The results showed that compared to raccoon dogs fed the AM0 diet, those fed the AM5 and AM10 diets had no significant difference in growth performance, while those fed the AM15 diet experienced a significant decrease. Raccoon dogs fed the AM5 diet had no significant effect on the nutrient apparent digestibility. Dietary supplementation with alfalfa meal significantly decreased serum urea levels and increased the antioxidant capacity of raccoon dogs. The intestinal microbiome analysis showed that the richness and diversity of colonic microbiota significantly increased in the AM15 group. With the increase in dietary alfalfa meal levels, the relative abundance of fiber-degrading bacteria in the colon of raccoon dogs, such as Treponema, Phascolarctobacterium, and Christensenellaceae R-7 group, increased. However, the relative abundance of pathogenic bacteria, including Anaerobiospirillum, decreased. In conclusion, the inclusion of 5% alfalfa meal in the raccoon dogs’ diet had no effect on growth performance, but it exhibited the potential to improve serum antioxidant capacity and intestinal microbiota. This indicates that raccoon dogs have a certain tolerance to the addition of alfalfa meal in their diet.

The intracellular protozoan Toxoplasma gondii is distributed worldwide and infects many species of warm-blooded animals. Most mammals, including humans, can serve as intermediate hosts. This pathogen, with its zoonotic potential, causes toxoplasmosis, a condition that can range from subclinical to fatal in humans. It is therefore important to assess the occurrence of the pathogen, even if only indirectly through the detection of antibodies. Epidemiological data on the seroprevalence in wild animals, including invasive species, are rare in Poland. Therefore, we tested 197 wild raccoons (Procyon lotor) and 89 raccoon dogs (Nyctereutes procyonoides) from Zgorzelec County, southwestern Poland, for the presence of antibodies. Samples were collected between January 2019 and December 2020 and analysed using a commercial indirect modified agglutination test (MAT, cut-off 1:25). The statistical analysis revealed significant differences in seroprevalence between the two predatory species. Of the 197 surveyed raccoons, 96 (48.73%; 95% confidence interval (CI): 41.73–55.73%) tested positive, while 25 of the 89 raccoon dogs (28.09%; 95% CI: 18.70–37.48%) were positive. Regarding risk factors, body weight and sex influenced the presence of T. gondii antibodies in both the species, with a higher likelihood of seropositivity among heavier animals and females, respectively. For raccoon dogs, juveniles were more likely to be seropositive than adults at a given weight. Our results suggest that T. gondii infection is widespread in the regional raccoon and raccoon dog populations, indicating a high level of parasite circulation in the environment.

Sarcoptic mange was detected in five free-ranging raccoon dogs (Nyctereutes procyonoides) in the federal state of Schleswig-Holstein, Germany, during a health assessment study of invasive species, including raccoon dogs, carried out between 2021 and 2022. Four raccoon dogs showed severe lesions, including extensive alopecia with thickening and hyperpigmentation of the skin (lichenification). The fifth animal was less affected, showing only thinning of the hair coat in multiple body locations. Skin scrapings were performed and confirmed the presence of Sarcoptes scabiei. Histopathology of the skin revealed diffuse epidermal hyperplasia and hyperkeratosis, mild eosinophilic dermatitis, and varying amounts of intralesional mites. Staphylococcus pseudintermedius and Corynebacterium auriscanis were detected in the skin samples of the affected animals, indicating a secondary bacterial infection. The source of sarcoptic mange remains unclear; interspecies transmission via direct or indirect contact seems likely. Raccoon dogs are therefore a potential vector for sarcoptic mange, and their behaviour could contribute to disease spread and persistence.

Platycladus orientalis leaves are rich in flavonoids and polysaccharides, which offer high medicinal and nutritional benefits. This study aimed to investigate the impact of P. orientalis leaf extract (PLE) on the growth performance, fur quality, serum parameters, and intestinal microbiota of raccoon dogs. Sixty healthy male black raccoon dogs, aged 85 (±5) days, were randomly assigned to four groups and fed a basal diet supplemented with 0, 0.25, 0.50, and 1.00 g/kg PLE for 125 days (designated as groups P0, P1, P2, and P3, respectively). The results revealed that the raccoon dogs in group P1 exhibited increased average daily gain and underfur length while showing a decreased feed/gain ratio compared to group P0 (p < 0.05). However, the heart index in group P2 was significantly lower than in group P0 (p < 0.05), and the kidney index and serum alanine aminotransferase activities in group P3 were higher than in groups P2 and P0 (p < 0.05), suggesting potential adverse effects at higher PLE dosages. Notably, dietary PLE supplementation led to a reduction in serum glucose concentrations (p < 0.05), which may have implications for glucose regulation. Furthermore, the study explored the impact of dietary supplementation with 0.25 g/kg PLE on the raccoon dogs’ intestinal microbiota using high-throughput sequencing. The results showed significant alterations in the microbial community structure, with a notable decrease in the abundance of Prevotella copri in response to 0.25 g/kg PLE supplementation (p < 0.05). In conclusion, supplementing raccoon dogs’ diet with 0.25 g/kg PLE can lead to improved growth performance and a positive influence on the intestinal microbiota. However, caution should be exercised regarding higher dosages, as they may have adverse effects on certain parameters. As a result, PLE holds promise as a potential feed additive for fur animal production.

Trichinella spp. are nematodes distributed throughout the world that affect an impressive number of host animals (mammals, birds, and reptiles) involved in the evolution of two cycles, the domestic and the sylvatic. The raccoon dog (Nyctereutes procyonoides) is an omnivorous mammal with great ecological plasticity. The expansion of the raccoon dog in Europe is associated with the risk of the introduction and spread of different pathogens, especially zoonotic ones (Trichinella, Echinococcus). Currently, the raccoon dog’s range in Romania is limited to the Danube Delta area, the Lower Danube Meadow, and the Prut Meadow. The aim of this study was to examine the presence of Trichinella larvae isolated from the muscles of raccoon dog from six hunting funds of Giurgeni, Ialomița County, Romania. The muscle samples were examined via artificial digestion, and the obtained larvae were processed via multiplex PCR. The PCR-amplified ESV and ITS1 DNA fragments were then sequenced for species confirmation. The species Trichinella britovi, which is the most common species identified in wild carnivores in temperate zones, was confirmed. Although T. britovi has been reported in several host animals in Romania, this case report confirms its presence in the raccoon dog for the first time.

The present investigation endeavours to discern dental and non-dental pathologies affecting cranial structures of raccoon dogs, while focusing on cases of periodontitis. Furthermore, the study aims to conduct a comparative analysis based on sex and the nature of the pathologies encountered. The number of investigated skulls amounted to 126, including 76 males and 50 females. The predominant pathology identified was hypodontia, which accounted for 26.7% of males and 20% of females. Notably, the majority of hypodontia cases involved the absence of the mandibular third molar. Another noteworthy pathology was various stages of periodontitis, with rates ranging from 21.3% in males to 8% in females. Other pathologies, like tooth fractures and abrasion, were significantly less encountered. Excessive bone formation was relatively abundant and localized in specific areas—the parietal bone and the occipital regions. This tendency was observed in 8% of male cases and 6% of females. We found that the total number of dental and skull-bone pathologies is significantly more common in males than in females (p = 0.003). Additionally, the total number of various cases of periodontitis is more common in males too (p = 0.04).

The monitoring of medium-sized carnivores is essential because of their role in disease transmission and as predators. We focused on red foxes, badgers, raccoon dogs, and domestic dogs, and considered 9441 ha of field–forest mosaic in Central Poland. We compared current (2011–2018) abundance (i.e., number of natal dens recorded annually) and breeding parameters (assessed with the aid of camera traps) with published past data (1980s–1990s). The red fox population increased after rabies vaccinations were introduced and has increased further in the last few years. The population is now stable, which suggests that other factors, possibly mange, limit the population instead. Contrary to historical data, one-fourth of red fox females now breed outside of forests areas, indicating the high plasticity of the species. The number of natal dens of badgers and recruitment rates have also increased. The mean litter sizes of these two species are positively affected by small rodent availability. The raccoon dog, which is an alien and invasive species, used to be recorded sporadically but now breeds regularly (1.8 breeding cases yearly). Nowadays, free-ranging/feral domestic dogs are not controlled by culling, so they have started to breed in the wild (1.6 cases per year), which is a new occurrence.

Unlike farm animals, wild animals are not subject to continuous health surveillance. Individual projects designed to screen wildlife populations for specific pathogens are, therefore, also of great importance for human health. In this context, the possible formation of a reservoir for highly pathogenic zoonotic pathogens is a focus of research. Two of these pathogens that have received particular attention during the last years are the novel severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), due to its fast global spread and high impact to the human health, and, since its introduction into Germany, the flavivirus West Nile virus (WNV). Especially in combination with invasive vertebrate species (e.g., raccoons (Procyon lotor) and raccoon dogs (Nyctereutes procyonoides) in Germany), risk analysis must be done to enable health authorities to assess the potential for the establishment of new wild life reservoirs for pathogens. Therefore, samples were collected from raccoons and raccoon dogs and analyzed for the presence of SARS-CoV-2 and WNV infections in these populations. Molecular biological and serological data obtained imply that no SARS-CoV-2 nor WNV reservoir has been established in these two wild life species yet. Future investigations need to keep an eye on these invasive carnivore populations, especially since the close contact of these animals to humans, mainly in urban areas, would make animal–human transmission a challenge for human health.

Invasive mammal species outside their natural range are causing damage to native ecosystems. Raccoon dogs were first observed in Lithuania in 1948, and since then, they have spread across the country. Surveys of this species stopped in 1997; therefore, numbers and trends are currently unknown. Raccoons were first observed in Lithuania in 2012, with only a few sporadic reports over the decade. Both species are listed as EU species of concern. Between September 2019 and July 2021, we evaluated the distribution and density of these animals using camera traps (system with a motion trigger/sensor that activates a camera to take a photograph when an animal is present) at 85 locations with a total sampling effort of 11,501 camera trap days. Raccoon dogs were identified in 57 locations (67.1% of all surveyed) and raccoons in 1 location (1.2%). The average relative shooting frequency of raccoon dogs was 5.12 photos/100 days and that of raccoons was 0.18 photos/100 days. The abundance of raccoon dog was not uniform. In the northeastern part of Lithuania, their relative shooting frequency was significantly higher than in western part (6.26 and 2.31 photos/100 days, respectively; p < 0.05). Raccoons were present in only one location; however, during the study period, they were registered 21 times. This indicates that a viable population has developed and could become a source of further invasion in the nearest future, requiring immediate control actions.

The raccoon (Procyon lotor) and the raccoon dog (Nyctereutes procyonoides) were introduced to Europe and, in the past decades, their populations have increased and adapted to synanthropic environments across Europe. In view of their possible further spread in Europe, the invasive species should be examined as potential reservoirs for helminths, including tapeworms. This study aims to investigate the prevalence and diversity of tapeworms in introduced wild carnivores in Poland by identifying cestode species based on copro-DNA analysis. A total of 214 individual fecal samples from non-native invasive carnivores, i.e., raccoons and raccoon dogs, and additionally 47 samples from native carnivores, i.e., European badgers (Meles meles), were analyzed for the presence of cestodes. PCR analysis of fecal samples targeting a fragment of mitochondrial (mt) 12S rRNA gene revealed the presence of cestode DNA in 19 of 103 (18.4%) raccoons, in 13 of 111 (11.7%) raccoon dogs and in 23 of 47 (48.9%) badgers. Sequence analysis demonstrated the presence of Mesocestoides litteratus in raccoons and raccoon dogs, while Mesocestoides lineatus was identified only in two samples derived from raccoon dogs. Moreover, in this study, Atriotaenia incisa was for the first time molecularly characterized by using fragments of mt 12S rRNA gene, and the DNA of this cestode species was detected in the fecal samples of all the examined host species.

Wild carnivores, both introduced and native species, are able to adapt well to peri-urban environments, facilitating cross-species pathogen transmission with domestic animals, and potentially humans. The role of wild living reservoir hosts cannot be ignored because of their known carriage of E. bieneusi zoonotic genotypes. In the past decades, populations of wild living carnivores, i.e., native, such as red foxes, and invasive, such as raccoon dogs and raccoons, have increased and adapted to synanthropic environments across Europe, including Poland. The knowledge concerning E. bieneusi genotype identification and distribution in wild carnivores is limited worldwide. A total of 322 individual fecal samples from six carnivore species, i.e., raccoon, raccoon dog, red fox, European badger, pine and beech martens, were collected and then analysed for the presence of E. bieneusi using the nested PCR method. Overall prevalence of the pathogen was estimated to be as high as 27.3%. The infection rates for E. bieneusi varied between the carnivore species, from 13.7% in beech martens to 40.4% in raccoon dogs. Based on sequence analysis of the ITS region of the rRNA gene marker, we detected five known genotypes of E. bieneusi in examined animals. In the invasive species, E. bieneusi NCF2 and D genotypes have been identified, whereas in the native ones, E. bieneusi NCF2, D, C, EbCar2 and Type IV genotypes were identified. All E. bieneusi genotypes recorded in this survey clustered in Group 1, showing their zoonotic potential. Our results provide the first description of the occurrence and genotypes of the microsporidian E. bieneusi in wild living population of raccoon dogs in Europe. Our findings are important for the study of pathogen epidemiology and emphasize the fact that the invasive and the native wild living carnivores, both widely distributed, should be considered more seriously as significant sources of zoonotic pathogens hazardous to domestic and farmed animals and humans.

Raccoon dogs (Nyctereutes procynoides) are canids indigenous to Eastern Asia being one of the most invasive non-native animals in Europe and potential vectors for several hazardous parasitic and viral diseases. To present, there is a lack of studies regarding objective techniques used to appreciate the integrity and functionality of the nervous system in this species. Brainstem auditory evoked potentials (BAER) is a cost-effective, quick and noninvasive technique to assess the functionality of nervous system. The aim of the study is to provide reference values and evaluates the reliability of BAER recording with needle electrodes in clinically healthy raccoon dogs. Nine individuals were investigated for BAER under xylazine and ketamine general anesthesia. Four waves (I, II, III and V) were identified and evaluated for latencies, morphologically similarity to those previously reported for other species (dogs, horses, cats, and ferret). Our data can be used in further studies to asses objectively the auditory system function in raccoon dogs.