Chromatic discrimination in fixed saturation levels from tufted capuchin monkeys with different color vision genotypes.

Recent research has proposed new approaches to investigate color vision in Old World Monkeys by measuring suprathreshold chromatic discrimination. In this study, we aimed to extend this approach to New World Monkeys with different color vision genotypes by examining their performance in chromatic discrimination tasks along different fixed chromatic saturation axes. Four tufted capuchin monkeys were included in the study, and their color vision genotypes were one classical protanope, one classical deuteranope, one non-classical protanope, and a normal trichromat. During the experiments, the monkeys were required to perform a chromatic discrimination task using pseudoisochromatic stimuli with varying target saturations of 0.06, 0.04, 0.03, and 0.02 u'v' units. The number of errors made by the monkeys along different chromatic axes was recorded, and their performance was quantified using the binomial probability of their hits during the tests. Our results showed that dichromatic monkeys made more errors near the color confusion lines associated with their specific color vision genotypes, while the trichromatic monkey did not demonstrate any systematic errors. At high chromatic saturation, the trichromatic monkey had significant hits in the chromatic axes around the 180° chromatic axis, whereas the dichromatic monkeys had errors in colors around the color confusion lines. At lower saturation, the performance of the dichromatic monkeys became more challenging to differentiate among the three types, but it was still distinct from that of the trichromatic monkey. In conclusion, our findings suggest that high saturation conditions can be used to identify the color vision dichromatic phenotype of capuchin monkeys, while low chromatic saturation conditions enable the distinction between trichromats and dichromats. These results extend the understanding of color vision in New World Monkeys and highlight the usefulness of suprathreshold chromatic discrimination measures in exploring color vision in non-human primates.

Measurement of Salivary Cortisol in Two New World Primate Species.

Glucocorticoids (GCs) are mammalian steroid hormones involved in a variety of physiological processes, including metabolism, the immune response, and cardiovascular functions. Due to their link to the physiological stress response, GC measurement is a valuable tool for conservation and welfare assessment in animal populations. GC levels can be measured from different matrices, such as urine and feces. Moreover, especially in captive settings, measuring GCs from saliva samples proved particularly useful as those samples can be collected non-invasively and easily from trained animals. Salivary GC levels can be measured using a variety of analytical methods, such as enzyme immunoassays. However, it is crucial to validate the analytical method for each specific application and species when using a new matrix. Using high-pressure liquid chromatography and a cortisol enzyme immunoassay, we show that the main glucocorticoids secreted in the saliva of squirrel monkeys and brown capuchin monkeys are cortisol and cortisone. Our biological validation found the expected salivary cortisol level to decline throughout the day. Our findings support the reliability of salivary cortisol measurements and their potential to be used as a valid tool in research and welfare assessment for these non-human primates.

Detection of herpesviruses in neotropical primates from São Paulo, Brazil.

Transmission of herpesvirus between humans and non-human primates represents a serious potential threat to human health and endangered species conservation. This study aimed to identify herpesvirus genomes in samples of neotropical primates (NTPs) in the state of São Paulo, Brazil. A total of 242 NTPs, including Callithrix sp., Alouatta sp., Sapajus sp., and Callicebus sp., were evaluated by pan-herpesvirus polymerase chain reaction (PCR) and sequencing. Sixty-two (25.6%) samples containing genome segments representative of members of the family Herpesviridae, including 16.1% for Callitrichine gammaherpesvirus 3, 6.1% for Human alphaherpesvirus 1, 2.1% for Alouatta macconnelli cytomegalovirus, and 0.83% for Cebus albifrons lymphocryptovirus 1. No co-infections were detected. The detection of herpesvirus genomes was significantly higher among adult animals (p = 0.033) and those kept under human care (p = 0.008671). These findings confirm the importance of monitoring the occurrence of herpesviruses in NTP populations in epizootic events.

Revisiting the mark test for mirror self-recognition.

Despite half a century of research, few species have exhibited convincing evidence of mirror self-recognition. Several methodological objections to Gallup's mark test have been raised, but empirical studies have shown that methodology does not adequately explain why most species fail to recognize themselves in mirrors. However, a potential issue was constantly overlooked: mirror ecological relevance. Although reflective surfaces in nature are horizontal, previous studies indeed used vertical mirrors. The present study revisited the mark test to address this issue in an experiment with capuchin monkeys (Sapajus apella). Additionally, a new procedure based on sticker exchange was designed to maximize mark attractiveness. Subjects were first trained to exchange stickers, habituated to being head-touched, and exposed to a horizontal mirror. Then, their mirror self-recognition was tested by surreptitiously placing a sticker on their forehead before requesting them to exchange stickers. None of the monkeys removed the sticker from their forehead in the presence of the mirror. In line with previous studies, this result suggests that capuchin monkeys lack the ability to recognize themselves in mirrors. Nonetheless, this modified mark test could prove useful in future studies, including investigation of interindividual variability of mirror self-recognition in self-recognizing species.

Comparative economics: how studying other primates helps us better understand the evolution of our own economic decision making.

The origins of evolutionary games are rooted in both economics and animal behaviour, but economics has, until recently, focused primarily on humans. Although historically, specific games were used in targeted circumstances with non-human species (i.e. the Prisoner's Dilemma), experimental economics has been increasingly recognized as a valuable method for directly comparing both the outcomes of economic decisions and their underlying mechanisms across species, particularly in comparison with humans, thanks to the structured procedures that allow for them to be instantiated across a variety of animals. So far, results in non-human primates suggest that even when outcomes are shared, underlying proximate mechanisms can vary substantially. Intriguingly, in some contexts non-human primates more easily find a Nash equilibrium than do humans, possibly owing to their greater willingness to explore the parameter space, but humans excel at more complex outcomes, such as alternating between two Nash equilibria, even when deprived of language or instruction, suggesting potential mechanisms that humans have evolved to allow us to solve complex social problems. We consider what these results suggest about the evolution of economic decision-making and suggest future directions, in particular the need to expand taxonomic diversity, to expand this promising approach. This article is part of the theme issue 'Half a century of evolutionary games: a synthesis of theory, application and future directions'.

Follicular Atresia, Cell Proliferation, and Anti-Mullerian Hormone in Two Neotropical Primates (Aotus nancymae and Sapajus macrocephalus).

This study evaluated the follicular atresia, cell proliferation, and anti-Mullerian hormone action in Aotus nancymae and Sapajus macrocephalus during three sexual phases (follicular, luteal, and gestational). Follicular quantification and immunolocalization of Caspase-3 protein, B-cell lymphoma 2 (BCL-2), proliferating cell nuclear antigen (PCNA), and anti-Mullerian hormone (AMH) were performed. A significant difference in the quantification between preantral and antral follicles, with a progressive decrease in the antrals, was identified. Protein and hormonal markers varied significantly between follicle cell types (A. nancymae p = 0.001; S. macrocephalus, p = 0.002). Immunostaining in the preantral and antral follicles was present in all sexual phases; for Caspase-3, in granulosa cells, oocytes, and stroma; for BCL-2, in granulosa cells, oocytes, and theca; and for PCNA and AMH, in oocytes and granulosa cells. The immunostaining for Caspase-3 was more expressive in the preantral follicles (follicular phase, p < 0.05), while that for BCL-2 and PCNA was more expressive in the antral follicles of the follicular phase. The AMH was more expressive in the primary and antral follicles of nonpregnant females, in both the follicular and luteal phases. Our results contribute to understanding the ovarian follicular selection, recruitment, and degeneration of these species.

Architecture of the inferior parietal cortex in capuchin monkey.

We studied the organization of the inferior parietal cortex (IPC) in five capuchin monkey (6 hemispheres) using cytoarchitectonic (Nissl), myeloarchitectonic (Gallyas), and immune-architectonic (SMI-32 monoclonal antibody) techniques. We partitioned the IPC into five distinct areas: PFG, PG, Opt, PFop, and PGop. Since we used parasagittal sections, we were not able to study area PF due to its far lateral position, which yielded slices that were tangential to the pial surface. Areas PFG, PG, and Opt were in the convexity close to the lateral sulcus, while PFop and PGop were positioned more posteriorly, in the opercular region of IPC. Of all the five regions, area Opt was the one most similar to its analogue in the macaque, especially as revealed with SMI-32 staining. Namely, in both primate species area Opt showed a low density of large pyramidal neurons. Additionally, the apical dendrites of these neurons were sparse and vertically orientated, resembling columns. We also found area PG to be similar: both species exhibited cell body layers with a radial arrangement. On the other hand, Nissl staining revealed area PFG to be architectonically different between New and Old-World monkeys: PFG in the capuchin showed a comparatively higher cell density than in macaques, especially in layers II and IV. These results suggest that evolution may have enabled the functional specialization of these brain regions based on behavioral demands of upper limb use. The small differences in the IPC of the two primates may be linked to interspecies variability.

Hematological reference values for Alouatta palliata (Primates: Atelidae) and Cebus imitator (Primates: Cebidae) from the Pacific Coast of Costa Rica / Valores de referencia hematológicos para Alouatta palliata (Primates: Atelidae) y Cebus imitator (Primates: Cebidae) de la costa Pacífica de Costa Rica

Abstract Introduction: Wildlife hematological patterns are fundamental for health monitoring, and allows elucidating variations both within and between populations. Among these, hematological parameters are particularly valuable to evaluate the health status of neotropical primate species in the wild. Objective: To define hematological reference values for two species of monkeys in Costa Rica. Methods: During 2014, we collected blood samples from free-ranging mantled howler monkeys, Alouatta palliata (17 females, 18 males) and white-faced capuchin monkeys, Cebus imitator (5 females, 7 males) in seven localities of the Costa Rican Pacific coast. Results: For both species, the hematological values were higher in males, and howler monkey populations differed significantly except for platelets. Conclusions: These hematological values, which differ by sex and locality, will help evaluate the health status of these neotropical primate populations.

Resumen Introducción: Los patrones hematológicos de la vida silvestre son fundamentales para el monitoreo de la salud y permiten dilucidar las variaciones tanto dentro como entre poblaciones. Entre estos, los parámetros hematológicos son particularmente valiosos para evaluar el estado de salud de las especies de primates neotropicales en la naturaleza. Objetivo: Definir valores de referencia hematológicos para dos especies de monos en Costa Rica. Métodos: Durante el 2014 recolectamos muestras de sangre de monos aulladores de manto, Alouatta palliata (17 hembras, 18 machos) y monos capuchinos cariblancos, Cebus imitador (5 hembras, 7 machos) en siete localidades de la costa Pacífica de Costa Rica. Resultados: Para ambas especies, los valores hematológicos fueron mayores en los machos, y las poblaciones de monos aulladores difirieron significativamente con excepción de las plaquetas. Conclusiones: Estos valores hematológicos, que difieren según el sexo y la localidad, ayudarán a evaluar el estado de salud de estas poblaciones de primates neotropicales.

Size and degree of protection of native forest remnants drive the local occupancy of an endangered neotropical primate.

Although the species-area relationship is well known, it may interact with and be augmented or cancelled out by other factors, such as local human disturbance. We used data on site occupancy of the Endangered blonde capuchin monkey (Sapajus flavius) based primarily on a standardized program of local interviews to model the influence of past human disturbance on the occurrence of this species across remaining forest patches of northeastern Brazil within the Atlantic Forest and Caatinga biomes. To do so, we assessed environmental covariates that best represent the history of human impacts. We then used single-species occupancy models to assess site occupancy, while controlling for detection error during sampling. Surprisingly, we obtained a higher occupancy rate in the more arid Caatinga remnants than in the more mesic Atlantic Forest. Habitat patch size, history of site protection, and annual precipitation were the best predictors of local occupancy. Historical human disturbance, including subsistence hunting, has exerted considerable impact on the modern distribution of the blonde capuchin, whose geographic range largely spans a region historically lacking any wildlife protection. Matrix vegetation structure across the Caatinga, which so far has averted large-scale mechanized agriculture, also creates a benign landscape that likely benefits contemporary capuchin occupancy. Local extinctions of this endangered primate will most likely continue unabated unless a ban on hunting in remaining Atlantic Forest and Caatinga fragments can be enforced.

The development of sex differences in play in wild white-faced capuchins (Cebus capucinus).

Many mammalian species display sex differences in the frequency of play behavior, yet the animal literature includes few longitudinal studies of play, which are important for understanding the developmental timing of sex differences and the evolutionary functions of play. We analyzed social play, solitary play, and grooming using an 18-year data set on 38 wild white-faced capuchin monkeys (Cebus capucinus) followed since infancy. Rates of each behavior were measured as the proportion of point samples taken during focal follows in which the individual engaged in each behavior. To determine sex differences in these rates, we ran a series of generalized linear mixed models, considering both linear and quadratic effects of age, and chose the optimal model for each of the three behavioral outcomes based on information criteria. Rates of both social play and solitary play decreased with age, with the exception of social play in males, which increased in the early juvenile period before decreasing. Male and female capuchins had different developmental patterns of social play, with males playing more than females during most of the juvenile period, but they did not display meaningful sex differences in solitary play rates. Additionally, males and females had different patterns of grooming over the lifespan: males participated in grooming at low rates throughout their lives, while adult females participated in grooming at much higher rates, peaking around age 11 years before declining. We suggest that male and female white-faced capuchins may adopt alternative social bonding strategies, including different developmental timing and different behaviors (social play for males vs. grooming for females). Our results were consistent with two functional hypotheses of play, the practice and bonding hypotheses. This study demonstrates that play behavior may be critical for the development of sex-specific social strategies and emphasizes the importance of developmental perspectives on social behaviors.

Metabolomic Profiling of Phloem Sap from Different Pine Species and Implications on Black Capuchin.

In most commercial pine farms in southern Brazil, black capuchin causes damage to wood and financial losses when it removes bark from some pine species to feed upon underlying vascular tissues. Therefore, this study aimed to evaluate the variability of the primary metabolites of phloem saps from 10 different species of pine by NMR spectroscopy, as well as the aroma compounds using SPME-GC-MS. Each technique provided a different set of metabolites that we can correlate to monkey predilection. The PCA showed monosaccharide (detected by NMR) and α-pinene (pine-like and resinous flavor descriptors) as attractive compounds for monkeys. On the other hand, the low content of monosaccharide and the high content of ß-phellandrene (citrus odor descriptor) was observed in less attacked pine species (P. patula). The data fusion on primary metabolites and aroma compounds corroborated the individual analyses, complementing the comprehension of the monkey predilection. Thus, P. elliottii was an avoided tree even with high content of sugars possibly due to its high content of ß-phellandrene (citrus odor). The results are useful for further behavioral studies to determine the role that each highlighted metabolite plays in chemically mediated animal-plant interactions.

Knowledge, Attitudes and Practices Regarding Sylvatic Rabies among High-Risk Households in Ceará State, Brazil.

Rabies transmitted by sylvatic populations has become an increasing concern in Brazil. A total of 113 participants with a history of contact with sylvatic populations were interviewed in 27 municipalities of Ceará State in northeast Brazil. Questionnaires included questions on knowledge, attitudes and practices (KAP) regarding sylvatic rabies. Most of the respondents (92%) knew about rabies and confirmed at least one species that transmitted the disease (79.6%). Of these respondents, 69% mentioned monkeys, and 67.2% mentioned dogs. However, 16% of the respondents listed an incorrect species. In general, knowledge on the symptoms and signs and on prevention measures was weak. The majority raised pets (93.8%), most commonly dogs and cats, and, of all the pets, 85.7% were claimed to be vaccinated against rabies. A total of 67.3% reported the appearance of free-living wild animals around their houses, mostly marmosets and wild canids; 18.3% reported that sylvatic populations had attacked animals or humans. Seventy-three percent had raised or still were raising wild animals as pets, mostly capuchin monkeys (79.5%) and marmosets (24.1%). This is the first KAP study on sylvatic rabies in Brazil. The data indicate important knowledge gaps and risk behavior within a high-risk population. There is a need for strengthening and improving sylvatic rabies surveillance and control, combined with the intensification of education and information campaigns.

Individualized Target Training Facilitated Transfer of Group Housed Capuchin Monkeys (Sapajus apella) to Test Cubicles and Discrimination of Targets on Computer Touch Screens.

Animals in captivity often experience fear, anxiety and aggression during non-voluntary procedures, leading to adverse behaviors and ineffective outcomes for both animals and caretakers. Negative reinforcement and punishment, often due to ignorance regarding animal learning, can hurt animal welfare. However, voluntary participation through positive reinforcement training (PRT) can decrease stress related to these procedures and increase desired behaviors. Our goal was to demonstrate the positive effects of "target training" on animal welfare by training 10 captive capuchin monkeys (Sapajus apella) in two experiments designed to facilitate movement from a group home enclosure to a test cubicle. In Experiment 1, each monkey was assigned an individualized target (a unique shape/color combination). In daily training sessions, the animal was rewarded with a click-sounding stimulus and a food reinforcer for (a) touching the target, (b) following the respective target into a test cubicle, and (c) touching progressively smaller targets until progressing to digitized images on a computer touch screen. All 10 animals learned to approach and touch their individual physical target in one or two sessions and were able to successfully transition this behavior to an image of their target on a touch screen, although they made more errors with the touch screen. In Experiment 2, the animals were presented with other animals' targets and novel targets. The seven animals in this experiment all touched their target at higher-than-chance rates in Trial 1 without explicit discrimination training, but only five reached the learning criteria for the task (>83% correct for three consecutive testing days. These results demonstrate that target training can make voluntary movement from group housing to test cubicles easier and benefit future animal care and procedures.

Evaluation of anaesthetic depth and cardiopulmonary effects of propofol infusion rate in Sapajus apella previously chemically contained with dextroketamine-midazolam.

BACKGROUND: This study evaluated the cardiopulmonary effects and anaesthetic depth induced by a propofol infusion rate of 0.8 mg/kg/min in monkeys (Sapajus apella). MATERIALS AND METHODS: Five capuchin monkeys received dextroketamine-midazolam intramuscularly. After a maximum duration of 5 min, the values of the physiological parameters were recorded, and a venous catheter was placed. After recovery from chemical restraint, the animals were anaesthetized with propofol intravenously, which was maintained for 1 h. Physiological parameters, anaesthetic depth, the time and quality of anaesthetic recovery were evaluated. RESULTS: Heart and respiratory rates, systolic blood pressure and rectal temperature during propofol infusion were lower than those during anaesthesia induction with dextroketamine-midazolam. Unconsciousness, muscle relaxation and lack of response to tail clamping were observed during propofol infusion. No animals showed excitement or vocalization during anaesthetic recovery. CONCLUSION: Propofol infusion rate of 0.8 mg/kg/min promoted surgical general anaesthesia, with transient hypotension, which showed excellent anaesthetic recovery.

What behaviour in economic games tells us about the evolution of non-human species' economic decision-making behaviour.

In the past decade, there has been a surge of interest in using games derived from experimental economics to test decision-making behaviour across species. In most cases, researchers are using the games as a tool, for instance, to understand what factors influence decision-making, how decision-making differs across species or contexts, or to ask broader questions about species' propensities to cooperate or compete. These games have been quite successful in this regard. To what degree, however, do these games tap into species' economic decision-making? For the purpose of understanding the evolution of economic systems in humans, this is the key question. To study this, we can break economic decision-making down into smaller components, each of which is a potential step in the evolution of human economic behaviour. We can then use data from economic games, which are simplified, highly structured models of decision-making and therefore ideal for the comparative approach, to directly compare these components across species and contexts, as well as in relation to more naturalistic behaviours, to better understand the evolution of economic behaviour and the social and ecological contexts that influenced it. The comparative approach has successfully informed us about the evolution of other complex traits, such as language and morality, and should help us more deeply understand why and how human economic systems evolved. This article is part of the theme issue 'Existence and prevalence of economic behaviours among non-human primates'.

Comparative anatomy of the brachial plexus and shoulder nerves of the Sapajus.

BACKGROUND: The capuchin is a neotropical primate that presents easy reproduction in captivity and is used in scientific research. The objective of this work was to describe the structure and the branching pattern of the brachial plexus of the capuchin and to compare the results with data from the literature for humans, chimpanzees, baboons and Callithrix. METHODS: Twelve specimens were used: eight males and four females. No animals were killed for the purpose of this study. RESULTS: The brachial plexus of Sapajus sp was constituted mainly from the ventral roots of the last four cervical spinal nerves, from C5 to C8, mainly, and the first thoracic nerve (T1). CONCLUSIONS: The pattern of formation of the brachial plexus of the capuchin monkey was more similar to that of Callithrix and baboons, perhaps because they are the only primates in this study to be essentially quadrupedal.

Trachea and lung anatomy applied to clinical and surgical procedures in Sapajus libidinosus (Spix, 1823).

BACKGROUND: The objective of the present study was to study the anatomy of the respiratory system of Sapajus libidinosus. METHODS: Ten corpses of adult animals were used. To analyze the bronchial tree, transparent acetic silicone was injected and then dissected. RESULTS: The trachea presented a mean of 32 rings. These spaces were delimited for tracheostomy and tracheotomy between the 1st and 3rd ring or between the 9th and 11th ring, and for thoracocentesis at the 7th or 8th intercostal space. For tracheostomy and tracheotomy, the best access point was in the ventral region of the neck and transverse incision of the rings. For thoracocentesis, cranioventral insertion of the catheter is recommended in the 8th intercostal space. CONCLUSIONS: The trachea and lung anatomy applied to clinical and surgical procedures the robust capuchin monkey is similar to both wild and domestic carnivores.

Reciprocity: Different behavioural strategies, cognitive mechanisms and psychological processes.

Reciprocity is probably one of the most debated theories in evolutionary research. After more than 40 years of research, some scientists conclude that reciprocity is an almost uniquely human trait mainly because it is cognitively demanding. Others, however, conclude that reciprocity is widespread and of great importance to many species. Yet, it is unclear how these species reciprocate, given its apparent cognitive complexity. Therefore, our aim was to unravel the psychological processes underlying reciprocity. By bringing together findings from studies investigating different aspects of reciprocity, we show that reciprocity is a rich concept with different behavioural strategies and cognitive mechanisms that require very different psychological processes. We reviewed evidence from three textbook examples, i.e. the Norway rat, common vampire bat and brown capuchin monkey, and show that the species use different strategies and mechanisms to reciprocate. We continue by examining the psychological processes of reciprocity. We show that the cognitive load varies between different forms of reciprocity. Several factors can lower the memory demands of reciprocity such as distinctiveness of encounters, memory of details and network size. Furthermore, there are different information operation systems in place, which also vary in their cognitive load due to assessing the number of encounters and the quality and quantity of help. We conclude that many species possess the psychological processes to show some form of reciprocity. Hence, reciprocity might be a widespread phenomenon that varies in terms of strategies and mechanisms.

CB1 receptor antagonism in capuchin monkeys alters social interaction and aversive memory extinction.

RATIONALE: The endocannabinoid system (eCS) is an important modulator of social anxiety and social reward, as well as memory functions. OBJECTIVES: The present study evaluated the role of eCS in social interactions and aversive memory extinction in capuchin monkeys (Sapajus spp.) by blocking the cannabinoid type 1 receptor (CB1r). METHODS: In experiment 1, spontaneous social and non-social behaviors of five capuchin males, each one living in triads with two other females, were observed after AM251 treatment (vehicle, 0.3, 1.0, and 3.0 mg/kg; i.m.). In experiment 2, seven male capuchin monkeys were trained to reach for a reward inside a wooden box. After training, they were given either vehicle or a 3.0-mg/kg i.m. dose of AM251 before a single aversive encounter with a live snake in the box. The latency to return to reach the reward inside the box in subsequent trials was measured. RESULTS: The 3.0-mg/kg dose significantly increased the time spent performing self-directed behaviors, while decreasing that of social interactions. No changes were observed in vigilance or locomotion. AM251 increased the latency to reach the reward after the aversive encounter. CONCLUSION: Taken together, these results suggest that CB1r antagonism induces social deficits without increasing anxiety levels and impairs the extinction of aversive memories. This behavioral profile in monkeys underscores the potential involvement of eCS signaling in the deficits observed in autism spectrum disorders.

Skeletopy of the medullary cone in Sapajus apella: Clinical implications in epidural anesthesia / Esqueletopia do cone medular em Sapajus apella: Implicações clínicas na anestesia epidural

This work aimed to describe the skeletopy of the medullary cone of the capuchin monkey (Sapajus apella) and to lay morphological foundations to propose a route of administration for epidural anesthesia. We used five females adults S. apella, and dissected them to study their medullary cone. The fixated animals were dissected, a skin incision was made from the dorsal median line, epaxial musculature and vertebral arcs was removed to expose the spinal cord, individualizing the medullary cone and the lumbar intumescence. The base of S. apella medullary cone was located near the L5 vertebra and the apex near S3, the structure was 4.5 cm in average. The evaluated specimens presented five lumbar and four sacral vertebrae. We concluded that the positioning of S. apella medullary cone is caudally than in other species, suggesting that the most appropriate location for epidural anesthetic procedures is the sacrocaudal region.

Este estudo visa descrever a esqueletopia do cone medular em macaco prego (Sapajus apella), com a intenção de estabelecer bases morfológicas para prestar o apoio à implementação de procedimentos anestésicos e outros procedimentos de rotina clínica-cirúrgica veterinária, dada a crescente importância do papel do veterinário na saúde dos animais selvagens. Cinco S. apella adultos fêmeas foram utilizadas neste trabalho e dissecados para o estudo do cone medular. Os animais fixados foram dissecados, foi feita uma incisão na pele na linha média dorsal, a musculatura epaxial e os arcos vertebrais foram removidos para exposição da medula espinhal, individualizando o cone medular e a intumescência lombar. A base do cone medular do S. apella foi observada na altura da vértebra L5 com o ápice em S3, com comprimento médio de 4,5 cm. Os espécimes avaliados apresentaram cinco vértebras lombares e quatro sacrais. Conclui-se que o posicionamento do cone medular do S. apella é mais caudal em relação às outras espécies. Por conseguinte, é sugerido que o local mais apropriado para o procedimento anestésico peridural é a sacrocaudal região.