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Rescue behavior is considered a type of pro-social response, defined as a voluntary action directed to benefit another individual who is in a stressful or dangerous situation. In two experiments, we investigated whether dogs would rescue their owners when the person was trapped inside a wooden box and emitted clear signs of stress. The performance of these dogs was compared against that of a control group in which the owners remained calm while trapped. In addition, to assess if training modulated this behavior, we tested a group of dogs from the military trained in search and rescue tasks (Experiment 1). Results showed that dogs opened the box more frequently when the owner pretended to be stressed than when calm. Training shortened latencies to open the door but not the frequency of the behavior. In Experiment 2, we investigated if emotional contagion could be a possible mechanism underlying dogs' rescue responses by measuring dogs' behavior, heart rate, and saliva cortisol level in the stressed and calm conditions, and also controlled for obedience by having the calm owners call their pets while trapped. We replicated the findings of Experiment 1 as more dogs opened the door in the stressed owner condition than in the calm condition. In addition, we observed an increase in heart rate across trials in the stressed condition and a decrease across trials in the calm condition, but no differences in cortisol levels or stress-related behaviors between conditions. In brief, we found evidence that approximately half of the dogs without previous training showed spontaneous rescue behaviors directed to their owners. Neither was this behavior motivated by obedience nor by the motivation to re-establish social contact with the owner. We conclude that emotional contagion is a plausible mechanism underlying dogs' rescue behavior in the present protocol.

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The pink fairy armadillo Chlamyphorus truncatus is the smallest extant armadillo and one of the least-known fossorial mammals. The aim of this study was to establish if its middle ear is specially adapted to the subterranean environment, through comparison with more epigeic relatives of the groups Euphractinae (Chaetophractus villosus, Chaetophractus vellerosus, Zaedyus pichiy) and Dasypodinae (Dasypus hybridus). We examined the middle ears using micro-computed tomography and subsequent three-dimensional reconstructions. D. hybridus has a relatively small middle ear cavity, an incomplete bulla and 'ancestral' ossicular morphology. The other species, including Chlamyphorus, have fully ossified bullae and middle ear ossicles, with a morphology between 'transitional' and 'freely mobile', but in all armadillos the malleus retains a long anterior process. Unusual features of armadillo ears include the lack of a pedicellate lenticular apophysis and the presence, in some species, of an element of Paaw within the stapedius muscle. In common with many subterranean mammals, Chlamyphorus has a relatively flattened malleo-incudal articulation and appears to lack a functional tensor tympani muscle. Its middle ear cavity is not unusually enlarged, and its middle ear ossicles seem less robust than those of the other armadillos studied. In comparison with the euphractines, there is no reason to believe that the middle ear of this species is specially adapted to the subterranean environment; some aspects may even be indicative of degeneration. The screaming hairy armadillo, Chaetophractus vellerosus, has the most voluminous middle ear in both relative and absolute terms. Its hypertrophied middle ear cavity likely represents an adaptation to low-frequency hearing in arid rather than subterranean conditions.

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[This corrects the article DOI: 10.1371/journal.pone.0206513.].

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Biological invasions are one of the main components of human-caused global change and their negative impact on invaded ecosystems have long been recognized. Invasive mammals, in particular, can threaten native biodiversity and cause economic impacts in the region where they are introduced, often through a wide range of conflicts with humans. Although the wild boar, Sus scrofa, is considered by the IUCN as one of the 100 invasive species most damaging to biodiversity in the world, in Argentina there have only been a few studies focused on its ecology with most of them conducted in protected areas. In this study, we evaluated the effect of several factors related with human disturbance, landscape composition, degree of fragmentation and the presence of a potential competitor and a predator on the habitat use of wild boar using data from camera traps and site-occupancy modeling. Additionally, we described the daily activity pattern of the species and we studied the level of overlap with both a potential competitor and a predator. The sampling effort totaled 7,054 camera trap days. Farm density, proportion of shrubland and proportion of grassland with bushes were the detection variables included in the most supported model whereas proportion of grassland and capture rate of the Pampas fox Lycalopex gymnocercus were the occupancy variables included in the most supported model. However, the proportion of grassland was the only variable that showed statistically significant support in the averaged model, indicating that habitat use of wild boar in this area was significantly negatively affected by the level of grass cover. Wild boars were mostly nocturnal, with more activity between 21:00 and 3:00 and a peak around midnight. Wild boars showed a high level of overlap with the activity pattern of the Pampas fox and a low overlap with the activity pattern of the puma Puma concolor. Despite wild boar being introduced in Argentina a few decades ago, this study is the first landscape-scale research carried out in an agricultural landscape in Argentina and the first one based on camera-trapping data. Our study contributes valuable information that could be used to design strategies to reduce wild boar population or to minimize the damage caused by this invasive species in Argentina.

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There is some dispute regarding the role of experience in the development of dogs´ socio-cognitive abilities in their interaction with people. We sought to provide new evidence to this debate by comparing dogs with contrasting levels of experience with humans, in a task involving the discrimination of human generous and selfish attitudes. To this end, we compared the performance of adult family dogs against that of adult shelter dogs and puppies living in people´s homes. In training trials, the generous experimenter (G) signaled the bowl with food and allowed the dog to eat, whereas the selfish experimenter (S) also signaled the baited bowl, but she/he ate the food before the dog could have access to it. Then, subjects were allowed to freely choose between G and S in the choice test. The main finding was that adult subjects (both family and shelter dogs) developed a preference for G over S, but puppies did not. We conclude that the quality and/or quantity of everyday-contact with people did not affect the discrimination of human attitudes in the present protocol, but the amount of experience with people (in years) did matter. Finally, we discuss the relative role of domestication and ontogeny in the development of dogs´ socio-cognitive abilities.

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The role that mammalian carnivores play in ecosystems can be deeply altered by human-driven habitat disturbance. While most carnivore species are negatively affected, the impact of habitat changes is expected to depend on their ecological flexibility. We aimed to identify key factors affecting the habitat use by four sympatric carnivore species in landscapes of central Argentina. Camera trapping surveys were carried out at 49 sites from 2011 to 2013. Each site was characterized by 12 habitat attributes, including human disturbance and fragmentation. Four landscape gradients were created from Principal Component Analysis and their influence on species-specific habitat use was studied using Generalized Linear Models. We recorded 74 events of Conepatus chinga, 546 of Pseudalopex gymnocercus, 193 of Leopardus geoffroyi and 45 of Puma concolor. We found that the gradient describing sites away from urban settlements and with low levels of disturbance had the strongest influence. L. geoffroyi was the only species responding significantly to the four gradients and showing a positive response to modified habitats, which could be favored by the low level of persecution by humans. P. concolor made stronger use of most preserved sites with low proportion of cropland, even though the species also used sites with an intermediate level of fragmentation. A more flexible use of space was found for C. chinga and P. gymnocercus. Our results demonstrate that the impact of human activities spans across this guild of carnivores and that species-specific responses appear to be mediated by ecological and behavioral attributes.

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The use of environmental visual cues for navigation is an ability present in many groups of animals. The effect of spatial proximity between a visual cue and a goal on reorientation in an environment has been studied in several vertebrate groups, but never previously in amphibians. In this study, we tested the use of local visual cues (beacons) to orient in an open field in the terrestrial toad (Rhinella arenarum). Experiment 1 showed that toads could orient in space using 2 cues located near the rewarded container. Experiment 2 used only 1 cue placed at different distances to the goal and revealed that learning speed was affected by the proximity to the goal (the closer the cue was to the goal, the faster toads learned its location). Experiment 3 showed that the position of a cue results in a different predictive value. Toads preferred cues located closer to the goal more than those located farther away as a reference for orientation. Present results revealed, for the first time, that (a) toads can learn to orient in an open space using visual cues, and that (b) the effect of spatial proximity between a cue and a goal, a learning phenomenon previously observed in other groups of animals such as mammals, birds, fish, and invertebrates, also affects orientation in amphibians. Thus, our results suggest that toads are able to employ spatial strategies that closely parallel those described in other vertebrate groups, supporting an early evolutionary origin for these spatial orientation skills.

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Leptospirosis is a zoonosis of worldwide distribution. The aim of this study was to examine the presence of antibodies against 21 Leptospira reactive serovars in Chaetophractus villosus in La Pampa province, Argentina, using the microscopic agglutination test (MAT). Pathologic changes compatible with leptospirosis and in situ detection of the agent by immunohistochemistry were studied in 24 and 3 individuals respectively. Only 35/150 (23.3%) serum samples had antibodies against Leptospira sp. Six percent of the samples reacted with serovar Canicola, 4.7% with serovar Castellonis, 1.3% with serovar Icterohemorrhagieae and 0.7% with serovar Hardjo. Sixteen (10.6%) serum samples agglutinated with Castellonis-Icterohemorrhagiae and Canicola-Castellonis serovars, both with 4.7%, and Canicola-Hardjo and Castellonis-Canicola-Icterohemorrhagiae both with 0.6%. Fourteen animals had variable degrees of lesions, which were more severe in animals with higher serological titers (3200), and Leptospira sp. was detected in 3 animals by immunohistochemistry. These results represent the first record of the presence of Leptospira in C. villosus in La Pampa.

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Leptospirosis is a zoonosis of worldwide distribution. The aim of this study was to examine the presence of antibodies against 21 Leptospira reactive serovars in Chaetophractus villosus in La Pampa province, Argentina, using the microscopic agglutination test (MAT). Pathologic changes compatible with leptospirosis and in situ detection of the agent by immunohistochemistry were studied in 24 and 3 individuals respectively. Only 35/150 (23.3%) serum samples had antibodies against Leptospira sp. Six percent of the samples reacted with serovar Canicola, 4.7% with serovar Castellonis, 1.3% with serovar Icterohemorrhagieae and 0.7% with serovar Hardjo. Sixteen (10.6%) serum samples agglutinated with Castellonis­Icterohemorrhagiae and Canicola­Castellonis serovars, both with 4.7%, and Canicola­Hardjo and Castellonis­Canicola­Icterohemorrhagiae both with 0.6%. Fourteen animals had variable degrees of lesions, which were more severe in animals with higher serological titers (3200), and Leptospira sp. was detected in 3 animals by immunohistochemistry. These results represent the first record of the presence of Leptospira in C. villosus in La Pamp

La leptospirosis es una zoonosis de distribución mundial. Nuestro objetivo fue examinar la presencia de anticuerpos contra 21 serovares reactivos de Leptospira en Chaetopractus villosus en la provincia de La Pampa, Argentina, mediante la prueba de aglutinación microscópica (MAT). Se realizó el estudio histopatológico y la detección in situ del agente por inmunohistoquímica en 24 y 3 individuos, respectivamente. Solo 35/150 (23,3%) muestras de suero presentaron anticuerpos contra Leptospira sp. Seis por ciento reaccionaron al serovar Canicola; 4,7% a Castellonis; 1,3% a Icterohemorrhagieae y 0,7% a Hardjo. Dieciséis (10,6%) sueros aglutinaron con Canicola-Castellonis y Castellonis-Icterohemorrhagiae, ambos con 4,7%, y con Canicola-Hardjo y Castellonis-Canicola-Icterohemorrhagiae, ambos con 0,6%. En 14 animales se encontraron lesiones compatibles, las que resultaron más graves en animales con títulos serológicos elevados (3200). En 3 animales estudiados se detectó el agente causal por inmunohistoquímica. Estos resultados constituyen los primeros registros de la presencia de Leptospira en C. villosus en La Pampa

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Leptospirosis is a zoonosis of worldwide distribution. The aim of this study was to examine the presence of antibodies against 21 Leptospira reactive serovars in Chaetophractus villosus in La Pampa province, Argentina, using the microscopic agglutination test (MAT). Pathologic changes compatible with leptospirosis and in situ detection of the agent by immunohistochemistry were studied in 24 and 3 individuals respectively. Only 35/150 (23.3

) serum samples had antibodies against Leptospira sp. Six percent of the samples reacted with serovar Canicola, 4.7

with serovar Castellonis, 1.3

with serovar Icterohemorrhagieae and 0.7

with serovar Hardjo. Sixteen (10.6

) serum samples agglutinated with Castellonis-Icterohemorrhagiae and Canicola-Castellonis serovars, both with 4.7

, and Canicola-Hardjo and Castellonis-Canicola-Icterohemorrhagiae both with 0.6

. Fourteen animals had variable degrees of lesions, which were more severe in animals with higher serological titers (3200), and Leptospira sp. was detected in 3 animals by immunohistochemistry. These results represent the first record of the presence of Leptospira in C. villosus in La Pampa.

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Brucellosis is a zoonotic disease transmitted from an animal reservoir to humans. Both, wildlife and domestic animals, contribute to the spreading of these zoonosis. The surveillance of the animal health status is strictly regulated for domestic animals, whereas disease monitoring in wildlife does not exist. The aim of the present study was to provide data on the prevalence of anti-Brucella antibodies in Chaetophractus villosus from a region of La Pampa, Argentina to assess public health risks. The C. villosus is endemic to South America, and in Argentina it represents a food resource for human consumption. A total of 150 sera of armadillos bleeding between 2007 and 2010 were tested using buffered plate antigen test (BPAT), serum agglutination test (SAT), 2-mercaptoethanol (2-ME) and complement fixation test (CFT), for the detection of anti-Brucella antibodies. Antibodies to Brucella sp. were found in 16% (24:150) of the armadillos tested using the BPAT test. All 24 positive samples were confirmed by the SAT, 2-ME and CFT tests. Strain isolation was attempted from liver and spleen samples of two animals with positive serology. Isolates were characterized by conventional biotyping and identification of specific DNA using polymerase chain reaction (PCR). A total of 2 isolates were recovered from spleen and liver. Both of them were identified as Brucella suis biovar 1. This preliminary study provides the first report on the seroprevalence of brucellosis and describes the first isolate of B. suis biovar 1 in C. villosus in Argentina.

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Toxoplasma gondii is an obligate intracellular apicomplexan parasite that causes abortion and reproductive disorder in domestic animals. T. gondii is a common worldwide disease in homeothermic animals, including birds and humans. The aim of the present study was to determine the presence of antibodies against T. gondii in the armadillo Chaetophractus villosus in the province of La Pampa, Argentina. Serum samples were collected from 150 individuals (70 males and 80 females). For serological detection of T. gondii, a latex agglutination test was first performed and then positive sera were confirmed with an indirect hemagglutination test, using 1:4 to 1:64 dilutions. Results showed that 27% (41) of the samples presented titers for antibodies against T. gondii. There were not significant differences between the presence of antibodies against T. gondii and age or sexes of the armadillos. Results show that presence of T. gondii antibodies in armadillos were associated with presence of pigs, and sheep, however there was not association with chickens and dairy cattle in capture site. T. gondii has an important presence in C. villosus population, suggesting a potential zoonotic risk for humans and wildlife animals when C. villosus meats are consumed raw or undercooked. This is the first record of the presence of antibodies against T. gondii in C. villosus.

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Middle ears of adult Chaetophractus villosus, C. vellerosus and Zaedyus pichiy were studied for qualitative and quantitative comparisons. A great similarity in the overall shape of the middle ear structures was observed in the three species. The well-developed auditory bulla was formed by the intimate fusion of the tympanic and entotympanic. Internally, a recessus meatus and a wide epitympanic recess extending dorsally into an epitympanic sinus were recognized. The petrosal promontorium, nearly triangular, was the most salient feature in the tympanic cavity. The auditory ossicles corresponded to the transitional middle ear type. The m. tensor tympani and the m. stapedius were conspicuous. The lack of a stapedial artery was confirmed in all cases. The tympanic area and middle ear ossicles were relatively larger in C. vellerosus than in the other two species. It is hoped that the results of the present paper coupled to the bullar hypertrophy found in a previous work will provide a significant basis for future functional studies on the hearing capabilities in the dasypodids.

Se estudió cualitativa y cuantitativamente la morfología del oído medio en adultos de Chaetophractus villosus, C. vellerosus y Zaedyus pichiy. Se observó una gran similitud en las estructuras del oído medio de las tres especies. La bula auditiva, bien desarrollada, se observó formada por la fusión del timpánico y entotimpánico. Internamente se pudo reconocer un recessus meatus y un amplio receso epitimpánico que se extendía dorsalmente en un seno epitimpánico. El promontorio, casi triangular, fue la estructura más notoria del interior de la cavidad timpánica. Los huesecillos auditivos correspondieron al tipo transicional. Se observó un gran desarrollo en los músculos tensor del tímpano y estapedial. Se confirmó la falta de una arteria estapedial en las tres especies. El área del tímpano y los huesecillos auditivos fueron relativamente más grandes en C. vellerosus que en las otras dos especies. Se espera que los resultados del presente trabajo, sumados a la hipertrofia de la bula timpánica reportada previamente, provean una base significativa para futuros estudios sobre la capacidad auditiva en los dasipódidos.

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We injected 27 adult Molina's hog-nosed skunks (Conepatus chinga) intramuscularly by hand with ketamine hydrochloride (KH) and xylazine hydrochloride (XH) in the Pampas grassland of Argentina. Skunks were immobilized with a mean (±SD) dosage of 24.9±6.5 mg/kg KH and 1.9±0.6 mg/kg XH. The mean effective dosages of KH (27.6 mg/kg) and XH (1.7 mg/kg) were higher and lower, respectively, than those reported in skunks previously. Mean induction and recovery time were 5.3±1.9 min and 47.7±18.5 min, respectively. Hypothermia was the only problem detected in field immobilization and occurred in winter but did not appear to be associated with to drug doses. We conclude that KH/XH is a safe immobilizing drug combination for Molina's hog-nosed skunk.

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Knowledge of armadillo reproductive physiology is essential for developing ex situ and in situ assisted reproductive techniques for propagating and/or controlling populations of these animals. The present study included assessment of fecal sex steroids by radioimmunoassay, determining reproductive status via monitoring ovarian activity (in the wild) and therefore reproductive status, in wild females of the large hairy armadillo (Chaetophractus villosus) and the crying armadillo (Chaetophractus vellerosus) in the southern hemisphere. Plasma and fresh fecal progesterone concentrations were not significantly correlated in either species. However, in both species, there was a significant positive correlation between plasma progesterone and dry fecal progesterone concentrations (r = 0.82, P < 0.05 and r = 0.60, P < 0.05, respectively). Dry fecal progesterone and estradiol concentrations were measured in one captive C. villosus (average baseline progesterone and estradiol concentrations 28.72 ± 11.75 ng/g dry feces and 3.04 ± 0.80 ng/g dry feces, respectively) and one captive C. vellerosus (average baseline progesterone and estradiol concentrations 14.05 ± 3.03 ng/g dry feces and 3.46 ± 1.20 ng/g dry feces, respectively) to detect hormonal peaks over 1 y; these occurred from late fall to early summer. Feces from wild C. villosus and C. vellerosus were also collected over 1 y to determine progesterone peaks, which occurred in winter and spring in both species (with no peaks during the summer or fall). Accordingly, C. villosus and C. vellerosus had a seasonal reproductive pattern. The significant correlations between dry fecal and plasma progesterone concentrations validated this method for monitoring reproductive status in these species.

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Las reacciones citoquímicas en hematología forman parte del estudio morfológico en la identificación del linaje celular invo1ucrado en las leucemias agudas y en el diagnóstico diferencial de síndromes mielodisplásicos y mieloproliferativos. Se realizaron extendidos de sangre entera sin anticoagulante provenientes de diez armadillos adultos, Chaetophractus villosus. Las técnicas estandarizadas aplicadas fueron: peroxidasas, lípidos simples, hidratos de carbono, fosfatasa alcalinaleucocitaria y esterasas inespecíficas. Los resultados obtenidos mostraron una correspondencia unívoca con los elementos figurados maduros humanos, abriendo la posibilidad de emplear a este mamífero Como modelo experimental en desórdenes hematológicos.

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El bazo es un órgano multipotencial y en su microarquitectura se reflejan tanto la filogenia como la adaptación de cada grupo animal e inclusive de cada especie. Los armadillos son un clado antiguo y geográficamente aislado de mamíferos que muestra una mezcla de estructuras ancestrales y modernas. En este trabajo se estudian la microanatomía y citología del bazo del peludo chico Chaetophractus vellerosus. El material se fijó y procesó según las técnicas de rutina de microscopías óptica y electrónica. Los resultados muestran un órgano mediano, del tipo de acumulación, con la típica segregación de pulpas. La pulpa blanca está bien desarrollada pero menos organizada que en otros armadillos. Se observa la presencia de células morfológicamente similares a las foliculares dendríticas y a las interdigitantes, así como agrupamientos de células inmunocompetentes. Estas características apoyan la importancia del órgano en la función inmune. La pulpa roja es un entramado de espacios vasculares y células libres y fijas. Se reconocen, por primera vez en el Género, la presencia de sinusoides esplénicos. El tejido hemopoyético está presente pero menos desarrollado que en otros Euphractini. Se discute la organización y el tamaño del bazo en contextos filogenético y adaptativo.

The spleen is a multifunctional organ. Its microarchitecture reflects so well the phylogeny as the adaptation to niche in each animal group and inclusive in each species. Armadillos, as ancient and isolated mammals, show a mixture of ancestral and modern structures. In this work the microanatomy and cytology of the spleen of the little hairy armadillo Chaetophractus vellerosus was studied. The material was fixed and processed according to the typical methods for light and electron microscopy. Results show a cumulative medium sized spleen with the typical pulps. The white pulp is well developed but less defined than in other armadillos. The presence of follicular-dendritic-like cells and interdigitant dendritic-like cells, as well as clusters of immunocompetent cells agrees with an active immunological activity. The red pulp is a meshwork of circulatory spaces and cells. The presence of splenic sinusoids is recognized for the first time in the genus. Hemopoietic tissue is less developed than in other Euphractini. The microarchitecture and size of the spleen of C. vellerosus is discussed in a phylogenetic and adaptive context.

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Lipid classes and their fatty acids were compared in plasma from four mammals: a laboratory rodent, the mouse; two domestic animals, the cat and dog; and a wild animal, the South American armadillo, Chaetophractus villosus. In all, the most abundant lipoprotein was high-density lipoprotein (HDL). In the total lipid of plasma, phospholipids (PL) predominated in all four species, in correlation with the proportion of HDL, both being largest in dogs. The major PL was phosphatidylcholine (PC), followed by sphingomyelin (SM) and lysophosphatidylcholine. The total plasma lipid from the four species contained long-chain n-6 polyunsaturated fatty acids as the predominant acyl groups, followed by comparable proportions of total saturated and monoenoic fatty acids and small percentages of n-3 PUFA. The percentages of these four major groups of fatty acids in PC, SM, triacylglycerols and cholesterol esters were similar among species, but showed significant differences in the ratios between major individual fatty acids composing these groups.

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