Experimental inoculation of raccoons (Procyon lotor) with Spiroplasma mirum and transmissible mink encephalopathy (TME)

The primary objective of this study was to determine whether or not Spiroplasma mirum would be capable of producing lesions of transmissible spongiform encephalopathy (TSE) when inoculated in raccoons (Procyon lotor) and, if that was possible, to compare the clinicopathological findings with those of transmissible mink encephalopathy (TME) in the same experimental model. For this purpose, 5 groups (n = 5) of raccoon kits were inoculated intracerebrally with either S. mirum and/or TME. Two other groups (n = 5) of raccoon kits served as sham-inoculated controls. All animals inoculated with TME, either alone or in combination, showed clinical signs of neurologic disorder and were euthanized within 6 mo post-inoculation (MPI). None of the carcasses revealed gross lesions. Spongiform encephalopathy was observed by light microscopy and the presence of abnormal disease-causing prion protein (PrP(d)) was detected by immunohistochemistry (IHC) and Western blot (WB) techniques in only the raccoons administered TME. Raccoons inoculated with Spiroplasma, but not administered TME agent, were euthanized at 30 MPI. They did not show clinical neurologic signs, their brains did not have lesions of spongiform encephalopathy, and their tissues were negative for S. mirum by polymerase chain reaction (PCR) and for PrP(d) by IHC and WB techniques. The results of this study indicate that Spiroplasma mirum does not induce TSE-like disease in raccoons.     

Neuroaxonal dystrophy in raccoons (Procyon lotor) from Iowa.

During a 12-month period (1998-1999), microscopic evidence of neuroaxonal dystrophy (NAD) in medullae oblongata of raccoons (Procyon lotor) was observed in 17/39 (47% prevalence in adults) from Iowa, USA. Three of the animals were kits (<3 months), 26 were between 1 and 2 years, and 10 were over 7 years. Lesions were not seen in the medullae of the 3 kits. In young adults, the lesions were mild and were seen in 7 animals. More severe lesions were present in the 10 older raccoons. Grossly, the brains were unremarkable. Microscopically, NAD was confined to the dorsal caudal medulla, where certain nuclei (predominantly gracilis and cuneate) were bilaterally affected. Severely affected animals had vacuolar degeneration of neurons or neuronal loss and extensive areas of spongiosis. Tests for the presence of PrP(res) in the brain were negative. Spongiotic areas often contained axonal spheroids. Degenerate neurons and axons occasionally contained amphophilic periodic acid-Schiff-positive granular material. There was a paucity of inflammatory cells in the affected areas. Since lesions were not present in kits, were either absent or mild in young adults, and were severe in older raccoons, the findings may be related to advancing age. Neuroaxonal dystrophy has not been previously reported in raccoons. Retrospective examination of raccoon brains from the eastern and northwestern areas of the country revealed very low prevalence of NAD. Because of the apparently high prevalence of this condition at this geographic location, factors other than age (genetic, nutritional, and/or environmental) may influence this degenerative process in the brains of raccoons in Iowa.     

Naturally occurring spirochetes in the colonic mucosa of raccoons (Procyon lotor)

The large intestines of 21 raccoons (Procyon lotor; 11 wild caught, 10 laboratory confined) were examined for the presence of intestinal spirochetes. Light microscopy of sections stained with hematoxylin and eosin and Warthin-Starry stain showed the presence of spiral shaped organisms deep within the lumina of intestinal glands at the ileocolonic junction of 16 raccoons (76% prevalence). All laboratory-confined, group-housed raccoons harbored the organisms, but only 6/11 (55% prevalence) live-trapped raccoons were positive for these spirochetes. The organisms were free in the glandular lumina, and there were no microscopic lesions. Two types of spirochetes were identified in the colonic glands: a slender spirochete 10-13 microm in length, 0.3 microm in diameter, and possessing long, thin tapered ends and a larger, regularly waved spiral organism (0.5 microm in diameter). The slender spirochete did not resemble any of the known spirochete genera and failed to grow on medium used to propagate oral treponemes and members of the genus Brachyspira.     

Gastrointestinal helminths of feral raccoons (Procyon lotor) in Wakayama Prefecture, Japan

The population and distribution of feral raccoons (Procyon lotor) are expanding in Japan after escape or release from animal-owners. Wakayama Prefecture is one of the most typically devastated areas by this exotic carnivore, particularly in the last five years after a latent distribution for more than ten years. Official control measures of feral raccoons commenced in the summer of 2002 by several municipalities, and 531 animals collected in 12 municipalities between May 2003 and April 2005 were submitted for parasitological examination of gastrointestinal helminths. Detected parasites included six nematodes (Physaloptera sp. [prevalence; 5.1%], Contracaecum spiculigerum [0.9%], Strongyloides procyonis [25.5%], Ancylostoma kusimaense [0.8%], Arthrostoma miyazakiense [0.4%], and Molineus legerae [1.1%]), seven trematodes (Isthmiophora hortensis [4.9%], echinostomatid sp. with 34-39 collar spines [1.7%], Metagonimus takahashii [12.4%], M. yokogawai [0.8%], Plagiorchis muris [0.2%], Macroorchis spinulosus [1.9%], and Consinium ten [0.2%]), one cestode (Mesocestoides sp. [0.2%]), and six acanthocephalan spp. (Centrorhynchus bazalenticus [0.2%], Centrorhynchus teres [5.5%], Sphaerirostris lanceoides [2.4%], Plagiorhynchus ogatai [0.6%], Porrorchis oti [1.5%], and Southwelina hispida [1.9%]). Most of the collected parasites are food-borne, indigenous helminth species. Physaloptera sp. has never been recorded in indigenous wild carnivores in Japan, and resembles closely P. rara, prevalent in raccoons of North America, in morphology. The position of a pair of phasmids in the posteroventral region of the adult male, however, could differentiate it from P. rara. Since Strongyloides procyonis is known to cause creeping eruption as well as intestinal infection in a healthy human volunteer, we should be concerned about the rapid increase in the population and distribution of feral raccoons in Japan from the viewpoint of public health as well.     

Seasonal changes in spermatogenesis and peripheral testosterone concentration in raccoons (Procyon lotor) in Hokkaido

Feral raccoons (Procyon lotor) have been increasing in number since 1979 and are currently subject to pest control in Hokkaido. One of the reasons for the increase in numbers is thought to be the high reproductive potential of raccoons, but little is known about their reproduction. The main aim of this study was to clarify seasonal changes in spermatogenesis and peripheral testosterone concentration of raccoons in Hokkaido. In the present study, external characteristics and histology of the testis and epididymis and the plasma testosterone concentration were investigated in 68 feral, male raccoons culled for pest control and once a month in one live, captive male. The feral males exhibited seasonal changes in spermatogenesis, showing active spermatogenesis in autumn, winter and spring (October-June) with noted spermatogenesis and inactive spermatogenesis in summer (July-September) with lower mean levels of spermatozoa in the cauda epididymis. Even in the inactive period, spermatozoa were observed in about half of the individuals (14/26); therefore, individuals producing spermatozoa existed every month throughout the year. Testosterone concentrations were significantly high in the winter mating season. In the captive male, the testosterone concentrations were low from June to August, and spermatozoa could not be observed from July to September. These results suggest that raccoons exhibit seasonality of reproduction, but the time and duration of spermatogenetic decline varies widely among individuals. This individual variation in the inactive period is a feature of male raccoon reproduction and is unique among seasonally breeding mammals.     

First and second cattle passage of transmissible mink encephalopathy by intracerebral inoculation

To compare clinicopathologic findings of transmissible mink encephalopathy (TME) with other transmissible spongiform encephalopathies (TSE, prion diseases) that have been shown to be experimentally transmissible to cattle (sheep scrapie and chronic wasting disease [CWD]), two groups of calves (n = 4 each) were intracerebrally inoculated with TME agents from two different sources (mink with TME and a steer with TME). Two uninoculated calves served as controls. Within 15.3 months postinoculation, all animals from both inoculated groups developed clinical signs of central nervous system (CNS) abnormality; their CNS tissues had microscopic spongiform encephalopathy (SE); and abnormal prion protein (PrP(res)) as detected in their CNS tissues by immunohistochemistry (IHC) and Western blot (WB) techniques. These findings demonstrate that intracerebrally inoculated cattle not only amplify TME PrP(res) but also develop clinical CNS signs and extensive lesions of SE. The latter has not been shown with other TSE agents (scrapie and CWD) similarly inoculated into cattle. The findings also suggest that the diagnostic techniques currently used for confirmation of bovine spongiform encephalopathy (BSE) would detect TME in cattle should it occur naturally. However, it would be a diagnostic challenge to differentiate TME in cattle from BSE by clinical signs, neuropathology, or the presence of PrP(res) by IHC and WB.     

Prevalence and distribution of Baylisascaris procyonis in urban raccoons (Procyon lotor) in Winnipeg,Manitoba

The prevalence of Baylisascaris procyonis was estimated in the urban raccoon population of Winnipeg through the fecal flotation of raccoon feces collected at active latrines and through gross postmortem and fecal flotation of samples collected from nuisance raccoons. Fecal flotation of latrine-collected feces was positive in 33 of 89 samples and, of 52 latrines identified, 26 were positive on 1 or more occasions. Trapped individual raccoons subjected to postmortem examination were positive in 57 of 114 animals captured. Comparing a single fecal flotation to the gold standard of finding adult worms in the small intestine had a sensitivity of 78.9% and specificity of 92.9%. This study suggests that carriage of Baylisascaris procyonis is widespread in raccoons in the Winnipeg urban ecosystem. Raccoon latrines in Winnipeg should be treated as infectious sites and efforts should be made to limit access of pets and people at risk to those sites.     

Experimental oral administration of canine adenovirus (type 2) to raccoons (Procyon lotor).

Canine adenovirus type 2 (CAV2) has been proposed for recombinant vaccines to control rabies in wild animals. To evaluate the suitability of CAV2 as a safe vector for the genetically engineered vaccines, seven wild-caught raccoons (three males and four females) were administered CAV2 per os. Two of the animals were euthanatized on each of post-infection days 3, 6, and 14, and one was euthanatized on day 21. Two other control raccoons (a male and a female) were also euthanatized on day 21. Microscopic pulmonary lesions of multifocal necrotizing bronchiolitis with basophilic intranuclear inclusions were seen in 3/4 raccoons euthanatized on post-infection days 3 and 6. Ultrastructural examination of lungs with pulmonary lesions revealed hexagonal viral particles characteristic of adenoviruses. CAV2 is potentially pathogenic for raccoons, and this susceptibility should be of concern to developers of recombinant vaccines who intend to use CAV2 as a vaccine vector.     

Babesia microti-like parasites detected in feral raccoons (Procyon lotor) captured in Hokkaido, Japan

Raccoons (Procyon lotor), which have recently become feral in Japan, were examined for the presence of Babesia microti-like parasites. Out of 372 raccoons captured in the west-central part of Hokkaido, 24 animals with splenomegaly were selected and tested by nested PCR targeting the babesial 18S rRNA gene. B. microti-like parasites were detected in two of the 24 individuals, and their DNA sequences were identical to that of the B. microti-like parasite reported from raccoons in the United States, suggesting that the parasites were probably imported into Japan and that the life cycle of the parasite has already been established in the country. The potential risk of this B. microti-like parasite spreading among dogs and foxes in Japan will need to be carefully monitored, as parasitization by phylogenetically very close parasites has been reported from such animals.     

Baylisascaris procyonis in raccoons (Procyon lotor) from eastern Colorado, an area of undefined prevalence

Baylisascaris procyonis is a zoonotic parasite that has been documented in raccoons throughout much of the United States; however, no published information on its occurrence is available for the transition zone from the Great Plains to the Rocky Mountains. Because this parasite can cause neural larva migrans and diffuse unilateral subacute neuroretinitis in humans (as well as other hosts), a more complete understanding of the distribution of this parasite seems warranted for public health reasons. The purpose of this study was to begin to fill in the gaps in our knowledge of the distribution of B. procyonis in an area of the US where there is, currently, no published information available. Fifty-three raccoons were collected throughout eastern Colorado during 2007-2010. Forty-six were examined by necropsy and seven by fecal flotation. Age (11 juveniles, 25 adults) and sex (16 males, 19 females) of the raccoons were recorded when intact carcasses were available. When available, feces were further processed for the detection of Giardia and Cryptosporidium using a direct fluorescent antibody detection method. B. procyonis was found in 31 of 53 raccoons (58.5%, 95% CI=44.1%, 71.9%). Mean intensity was 11.7 with a range of 1-49 worms per infected individual. There was no significant difference between age or sex, and the presence of ascarids or the number of ascarids. Cryptosporidium spp. oocysts and Giardia spp. cysts were detected in 11/44 (25%; 95% CI: 13.2, 40.3) and 3/44 (6.9%; 95% CI: 1.4, 18.7) raccoons, respectively. The genotype of the Giardia present could not be determined. The genotype of five of six cryptosporidial isolates was 100% homologous to the skunk genotype while the sixth was 100% homologous to Cryptosporidium parvum. Based on these results, both B. procyonis and Cryptosporidium spp. appear to be prevalent in raccoons of eastern Colorado.     

Leptospirosis and tularaemia in raccoons (Procyon lotor) of Larimer County, [corrected] Colorado

Raccoons (Procyon lotor) are commonly implicated as carriers of many zoonotic pathogens. The purpose of this cross-sectional study was to look for Leptospira interrogans and Francisella tularensis in opportunistically sampled, free-ranging raccoons of Larimer Country, Colorado, USA. Sixty-five animals were included in the study and testing consisted of gross post-mortem examination, histopathology, and both immunohistochemistry and PCR for L. interrogans and F. tularensis. No significant gross lesions were identified and the most common histological lesions were lymphoplasmacytic interstitial nephritis and pulmonary silicosis; rare periportal hepatitis, splenic lymphoid hyperplasia and small pulmonary granulomas were also identified. Of 65 animals, 20 (30%) were positive for Leptospira on IHC but only one by PCR. Animals with inflammation in their kidneys were seven times more likely to be positive for Leptospira than animals without inflammation. The severity of inflammation was variable but often mild with minimal associated renal pathology. One animal was positive for Francisella on both IHC and PCR; IHC staining was localized to histiocytic cells within a pulmonary granuloma. In Colorado the significance and epidemiology of Leptospira is poorly understood. The high prevalence of infection in raccoons in this study population suggests that this species may be important in the regional epidemiology or could be used to estimate risk to domestic animals and humans. Identification of a single Francisella positive animal is significant as this is an uncommon disease in terrestrial animals within the state; the apparently higher prevalence in this peridomestic species implies that raccoons may be good indicators of the pathogen in the region. The results of this study suggest that raccoons may serve as effective sentinels for both Leptospira and Francisella in the state of Colorado. Further studies are needed to better characterize the prevalence and epidemiology of both organisms within the region.     

Experimental infection of sheep and goats with transmissible mink encephalopathy virus.

In a study to learn more about the pathogenicity of transmissible mink encephalopathy virus for the natural hosts of scrapie, 20 Cheviot sheep and 19 dairy goats were inoculated intracerebrally with the Idaho strain of the virus. Five sheep and nine goats became affected with a progressive neurological disease. The incubation period in the sheep varied from 45 to 80 months (mean, 65 months) and in the goats from 31 to 40 months (mean, 35 months). Except for degeneration of the cerebral cortex (neocortex), the disease was indistinguishable clinically and neurohistologically from scrapie. During two more passages of the virus in goats, the incubation period was shortened to 12 to 15 months, the morbidity rate rose to 100% (6/6 dairy goats and 3/3 African pygmy goats), and the cortical lesion became constant and more pronounced. By the intracerebral inoculation of pastel mink, transmissible mink encephalopathy virus was detected in the brains of several affected sheep and goats but not in extraneural sites (lymphoid tissues and intestine), except for a trace amount in the proximal colon of one goat. Even after two passages in goats, the virus remained nonpathogenic for the laboratory mouse. Despite the essential likeness of the experimental disease and scrapie, the common identity of their causal viruses remains to be determined. Even so, the results of this study are still compatible with the view that transmissible mink encephalopathy virus almost certainly is scrapie virus whose biological properties became altered by chance passage in mink, a carnivore and an aberrant host.     

Cerebrospinal fluid analysis of rabid and vaccinia-rabies glycoprotein recombinant, orally vaccinated raccoons (Procyon lotor)

Cerebrospinal fluid obtained from clinically normal free-ranging raccoons was analyzed and compared with CSF obtained from raccoons vaccinated orally with vaccinia-rabies glycoprotein (V-RG) recombinant virus vaccine and subsequently challenged peripherally with street rabies virus, and CSF from naive, rabies virus challenge-exposed control raccoons. Significant differences were not found in CSF of free-ranging or V-RG recombinant virus vaccine recipient raccoons, and there was no evidence of CNS invasion by V-RG virus. The CSF of naive, rabies challenge-exposed control raccoons contained high numbers of lymphocytes and monocytes, compatible with rabies virus encephalitis. Although V-RG orally vaccinated challenge-exposed raccoons were protected from lethal rabies virus infection, a mild lymphocytic pleocytosis was evident at 90 days after challenge exposure.     

Use of infrared thermography to detect signs of rabies infection in raccoons (Procyon lotor).

Infrared thermography was evaluated as a technique to determine if raccoons (Procyon lotor) experimentally infected with rabies virus could be differentiated from noninfected raccoons. Following a 10-day adjustment period, raccoons (n = 6) were infected with a virulent rabies street strain raccoon variant by injection into the masseter muscle at a dose of 2 x 10(4) tissue-culture infectious dose (TCID50) in 0.2 ml (n = 4) or 10(5) TCID50 in 1 ml (n = 2). Five of the six raccoons developed prodromal signs of rabies 17 to 22 days postinoculation (PI) and distinctive clinical signs of furious rabies between 19 and 24 days PI. At the time of euthanasia, which occurred 2 days after the onset of clinical signs of rabies, these five raccoons tested positive for rabies virus in brain tissue. Infrared thermal images of each raccoon were recorded twice daily during the preinoculation and PI periods. No apparent differences were identified among thermal temperatures compared among days for the eye, average body surface, and body temperature recorded from subcutaneous implants throughout the experiment for any of the six raccoons. However, increases in infrared surface temperature of the noses and differences in the visual thermal images of the noses were detected when animals began showing clinical signs of rabies. Differences were detected among the mean infrared nose temperatures for the disease progression intervals (F3.12 = 70.03, P < 0.0001). The mean nose temperature in the clinical rabies stage (30.4 +/- 3.5 degrees C) was significantly elevated over the prodromal stage (F1,12 = 151.85, P < 0.0001). This experiment provides data indicating that infrared thermography can be used in an experimental setting to detect raccoons in the infectious stage and capable of exhibiting clinical signs of rabies.     

Prevalence of psammoma bodies in meninges and choroid plexuses of raccoons (Procyon lotor) from Parramore Island, Virginia.

Microscopic evidence of multifocal mineralizations (psammoma bodies) were seen in brains of 33/53 (62%) raccoons (Procyon lotor) necropsied on Parramore Island, Virginia. Most mineralized foci had concentric laminations and were present in small capillaries of meninges of the brain (15/33), in choroid plexus (3/33), or at both these sites (13/33). In 2 raccoons, the lesions were confined to the meninges of the proximal cervical spinal cord. In most cases, the affected vessels appeared to have been completely occluded. However, no evidence of ischemic changes in the brain parenchyma was seen, and none of the raccoons had abnormal neurologic signs prior to euthanasia. The condition appears to be a common incidental histopathologic finding in raccoons from the eastern United States. Although the exact cause of this condition is not known, a primary vascular insult with resultant dystrophic mineralization of the affected vessels is suspected.     

Indices using external measurements for assessing fat deposition of adult feral raccoons (Procyon lotor) in Kanagawa Prefecture, Japan

We examined the use of external measurements and relative fat deposition of adult feral raccoons (Procyon lotor) to develop relative indices of body fat deposition in post-growth feral raccoons. From March 2006 to March 2010, 288 adult raccoon carcasses (110 males, 178 females) collected in Kanagawa Prefecture, Japan, which were determined to be 24 months old, were subjected to external measurements of body weight (BW), girth measurement (GM), and body mass index (BMI). To assess relative body fat deposition, we visually classified abdominal subcutaneous fat into three grades (Visible Fat Index [VFI]: I-III). Significant differences in the means of BW (both sexes:P<0.01), GM (females: P<0.05, males: P<0.01), and BMI (both sexes: P<0.01) were detected between seasons. Notably, the means of BW, GM, and BMI (all, both sexes: P<0.01) differed significantly between VFI grades. However, by discriminant analysis with BW, GM, and BMI as independent variables, we obtained a significant discriminant function (both sexes: P<0.01) for distinguishing VFI I from higher VFI grades, but no significant equation was obtained for distinguishing between VFI II and VFI III. Based on the obtained structure matrix of discriminant analysis, BMI was the most valuable component for the discrimination of VFI grades. Thus, we conclude that BMI is a suitable complementary index for assessing relative body fat deposition of adult feral raccoons in Kanagawa Prefecture and may be generalizable to populations in other areas.     

Cerebral larva migrans in a raccoon (Procyon lotor)

During 1997, gross and histopathologic examinations were performed on an adult female raccoon (Procyon lotor) that was live-trapped in Corvallis, Oregon. Multifocal eosinophilic granulomas indicative of neural and visceral larva migrans were observed. However, within these granulomas, the presence of parasitic larva was seen only in the cerebrum. Morphologic characteristics indicated that the nematode was an ascarid larva. However, it was smaller than the larva of Baylisascaris sp. This appears to be the first documented case of cerebral larva migrans in a raccoon.     

Prevalence of Salmonella, Yersinia and Campylobacter spp. in feral raccoons (Procyon lotor) and masked palm civets (Paguma larvata) in Japan

To estimate the public and animal health risk that alien species pose, the prevalence of Salmonella, Yersinia, and Campylobacter spp. in feral raccoons (Procyon lotor, n=459) and masked palm civets (Paguma larvata, n=153), which are abundant alien species in Japan, was investigated in urban and suburban areas of Japan. Salmonella enterica was detected from 29 samples [26 raccoons, 5.7%, 95% confidence interval (CI) 7.8-3.5%; three masked palm civets, 2.0%, 95% CI 4.2-0%]. Many of the isolates belonged to serovars that are commonly isolated from human gastroenteritis patients (e.g. S. Infantis, S. Typhimurium, and S. Thompson). The antimicrobial susceptibility test showed that 26.9 % of the isolates from raccoons were resistant to at least one antimicrobial agent, whereas none of the isolates from masked palm civets were resistant. Yersinia sp. was detected from 193 samples (177 raccoons, 38.6%, 95% CI 43.0-34.1%; 16 masked palm civets, 10.5%, 95% CI 15.3-5.6%). All virulent Yersinia strains belonged to Yersinia pseudotuberculosis, which was isolated from seven (1.5%, 95% CI 2.6-0.4%) raccoons and six (3.9%, 95% CI 7.0-0.8%) masked palm civets. According to the detection of virulence factors, all the Y. pseudotuberculosis isolates belonged to the Far Eastern systemic pathogenicity type. Campylobacter spp. was detected from 17 samples (six raccoons, 1.3%, 95% CI 2.3-0.3%; 11 masked palm civets, 7.2%, 95% CI 11.3-3.1%). Among these, three isolates from raccoons were identified as C. jejuni. These results showed that these pathogens can be transmitted by human activities, other wild animals, and the environment to feral raccoons and masked palm civets, and vice versa. As these animals have omnivorous behaviour and a wide range of habitats, they can play an important role in the transmission of the enteric pathogens.     

北美浣熊的饲养管理和繁殖

动物园饲养的浣熊科动物经常出现异常的繁殖行为:食仔和弃仔现象,而随后的人工哺育需要耗费大量时间和精力.2011年上海动物园新引进3对亚成体浣熊,在参考国内外文献资料中浣熊的野外繁殖习性的基础上,在圈养条件下探索降低异常繁殖行为的方法,于2012年首次使3对浣熊成功繁殖和育幼.本文就北美浣熊的野外习性、饲养管理、繁殖特性等,结合观察到的-窝幼仔的发育情况和行为表现做初步小结,以期为今后的繁殖工作打下基础,减少动物的异常繁殖行为.