Comparative study between ketamine-S-dexmedetomidine and ketamine-S-midazolam-methadone in the anesthesia of capuchin monkeys (Sapajus apella)

ABSTRACT: Anesthetic protocols have been developed to obtain the most effective and safe association in wildlife. This study compared the anesthetic effects and cardiorespiratory parameters of ketamine-S (+) (10 mg/kg)/dexmedetomidine (0.020 mg/kg) (KD ) and ketamine-S (+) (10 mg/kg)/midazolam (0.5 mg/kg)/methadone (1.0 mg/kg) (KMM ) in capuchin monkeys (Sapajus apella). Eight capuchin monkeys were randomly assigned to KD (n = 4) or KMM (n = 4) to evaluate induction, immobilization, and recovery scores, heart and respiratory rate parameters, besides systolic, mean, diastolic arterial pressure and arterial blood gas. There was no difference (P = 0.56) in the quality of induction, immobilization, and anesthetic recovery between the protocols. The time for anesthetic induction was 4 ± 1 min in the KD group and 5 ± 1 min in the KMM group, and these values were statistically equal (P = 0.28). The mean immobilization time in the KD and KMM groups were 35 ± 13 and 33 ± 15 min, respectively. Heart rate was lower in animals in the KD group (P < 0.001), while respiratory rate (P = 0.03), and mean blood pressure (P = 0.046) were higher than that of the animals in the KMM group. Respiratory acidosis occurred in the KMM group, with lower pH (7.25±0.047; P = 0.0055) and higher pCO2 (51 ± 6;mmHg; P = 0.008). Both protocols exhibited good induction quality, immobilization, and anesthetic recovery, despite cardiorespiratory and blood gas alterations observed, which warrants monitoring of cardiorespiratory variables during KD or KMM chemical restraint.

Matching physical properties of food and tools in three populations of wild capuchin monkeys

Robust capuchin monkeys (Sapajus) are known for accessing mechanically challenging food. Although presenting morphological adaptations to do so, several populations go beyond the body limitations, using tools, mainly stone tools, to expand their food range. Those populations are diverse, some using stones more widely than others. We know stone tool size correlates with the target's resistance within some populations, but we have no detailed comparisons between populations so far. This study described and compared general environmental data, food’s physical properties, and stone tools features on three populations of bearded capuchin monkeys (Sapajus libidinosus), including a new site. The differences we observed regarding stone tool use between the new site (CVNP) and the previously studied ones could be partially explained by ecological factors, such as the raw material and resource availability. However, other differences appear to be more related to behavioral traditions, such as the processing of Hymenaea at CVNP, where the monkeys use bigger stones than other populations to process the same kind of food, which present similar physical properties between sites. Possible cultural differences need to be compared within a larger number of areas to better understand capuchin monkey behavioral variability.

Observer effects in a remote population of large-headed capuchins, Sapajus macrocephalus

Human observers often are present when researchers record animal behavior, which can create observer effects. These effects are rarely explicitly investigated, often due to the assumption that the study animal is habituated to or unaffected by a human’s presence. We investigated the effect of human pressure gradients on a remote population of large-headed capuchins, Sapajus macrocephalus, looking specifically at the effects of number of observers, distance to observers, and distance to the research base. We conducted this study over 4 months in the Pacaya-Samiria Nature Reserve, Peru, and collected 199 two-minute focal samples of capuchin behavior. We found that capuchin monkeys fed less when human observers were closer to the focal individual, when more observers were present, and when capuchins were closer to the research base. We found no other consistent differences in capuchin monkey behavior across the measured human pressure gradients, although capuchins directed a high proportion of their vigilance toward humans (29% in adults and 47% in infants). Our results support the hypothesis that human pressure gradients influence animal behavior. Given the proportion of human directed vigilance, we recommend that all studies that use human observers to record animal behavior consider human-directed vigilance, record the number of observers, as well as the observer-focal animal distance, to check for these effects.

Eye preferences in capuchin monkeys (Sapajus apella)

This study explored whether capuchin monkey eye preferences differ systematically in response to stimuli of positive and negative valence. The ‘valence hypothesis’ proposes that the right hemisphere is more dominant for negative emotional processing and the left hemisphere is more dominant for positive emotional processing. Visual information from each eye is thought to be transferred faster to and primarily processed by the contra-lateral cerebral hemisphere. Therefore, it was predicted capuchin monkeys would show greater left eye use for looking at negative stimuli and greater right eye use for looking at positive stimuli. Eleven captive capuchin monkeys were presented with four images of different emotional valence (an egg and capuchin monkey raised eyebrow face were categorised as positive, and a harpy eagle face and capuchin monkey threat face were categorised as negative) and social relevance (consisting of capuchin monkey faces or not), and eye preferences for viewing the stimuli through a monocular viewing hole were recorded. While strong preferences for using either the left or right eye were found for most individuals, there was no consensus at the population-level. Furthermore, the direction of looking, number of looks and duration of looks did not differ significantly with the emotional valence of the stimuli. These results are inconsistent with the main hypotheses about the relationship between eye preferences and processing of emotional stimuli. However, the monkeys did show significantly more arousal behaviours (vocalisation, door-touching, self-scratching and hand-rubbing) when viewing the negatively valenced stimuli than the positively valenced stimuli, indicating that the stimuli were emotionally salient. These findings do not provide evidence for a relationship between eye preferences and functional hemispheric specialisations, as often proposed in humans. Additional comparative studies are required to better understand the phylogeny of lateral biases, particularly in relation to emotional valence.

Investigation of Cryptosporidium spp. in breeding nucleus of capuchin monkeys (Sapajus spp.)

Animals of the primate order are highly susceptible to parasitic infections due to their social organization, often in groups and interaction between individuals, facilitating the transmission of pathogenic agents, and may be even more prevalent in areas modified by anthropic action. The occurrence of the protozoan Cryptosporidium spp. in wildlife animals in captivity or free-living it characterizes great importance of Public Health mainly for its zoonotic potential. This parasite has a cosmopolitan distribution, causes gastrointestinal infection, and its transmission occurs via the fecal-oral route, either through water or through contaminated food. Cryptosporidiosis affects mammals, birds, reptiles and fish, this significant zoonotic potential, in addition to being directly related to the living conditions of the host and the quality of the environment. We investigated the occurrence of Cryptosporidium spp. in primates located at the Tufted Capuchin Monkey Procreation Center (School of Dentistry of Araçatuba - UNESP). Fecal samples from 49 asymptomatic primates of the species Sapajus spp. species were collected below their individual cages, the soil was lined with a plastic bag, thus hindering environmental contamination. The search for oocysts was carried out using the technique of Negative Malachite Green Staining, finding negativity in all samples examined, which suggests the absence of the protozoan Cryptosporidium spp. in primates studied in the breeding center of capuchin monkeys (Sapajus spp.), noting that they were asymptomatic.