Anatomia macroscópica interna e avaliação elétrica do coração de Bradypus variegatus / Internal macroscopic anatomy and electrical evaluation of the Bradypus variegatus heart

The Bradypus variegatus species presents peculiar anatomophysiological properties and many aspects of its organic systems still need to be clarified, especially regarding the cardiovascular system, given its participation in vital activities. Disorderly anthropic action has had drastic consequences in sloth populations and the need to treat sick and injured animals is increasingly common. To this end, the importance of knowing its characteristics is emphasized. Therefore, this study proposed to describe the internal macroscopic structures of the sloth's heart, as well as to measure the ventricular walls and indicate the electrical activity of the organ. For the dissections, 15 Bradypus variegatus cadavers were used (1 young female, 9 adults females and 5 adult males) belonging to the Área de Anatomia of the Departamento de Morfologia e Fisiologia Animal (DMFA), Universidade Federal Rural de Pernambuco (UFRPE), Recide, PE, Brazil. After they were fixed and preserved, the specimens received a midsagittal incision in the chest, followed by soft tissue folding and removal of ribs to access the heart. The organ was derived from the cavity and sectioned sagittal medially to identify its internal anatomy. Ventricular walls and interventricular septum were measured with a steel caliper (150 mm / 0.02 mm). An electrocardiogram was performed to determine the electrical profile on 5 healthy B. variegatus sloths, living under semi-livestock conditions at the Recife Zoo, PE, Brazil. The electrodes were taken from the regions, scapular and glutes of the animals that were called hugging a keeper during the procedure, carried out in the Zoo itself, using a portable device. Based on the data obtained, sloths have cardiac chambers separated by septa, however between atria and ventricles, in both antimeres, there are atrioventricular ostia, where valves are found, consisting of 3 valves on the right and 2 on the left. The atria are practically smooth inside and have their cavity enlarged by the atria, the right being larger than the left, these having a greater amount of pectineal muscles in relation to the atria. The ventricles have trabeculae and papillary muscles, 3 on the right and 2 on the left. These muscles hold the tendinous chords that connect the valves. The existence of trabeculae marginal septum was not evidenced. The thickness of the wall of the left ventricle, as well as that of the interventricular septum, proved to be greater than the thickness of the wall of the right ventricle, regardless of the age or sex of the animals. Based on the electrocardiographic recordings, the sloths presented sinus rhythm, with a heart rate between 67 and 100 bpm. The electrical axis ranged from -60º to -90º. The P wave is smoother than the QRS complex. While the S-T segment was classified as isoelectric. The T wave was shown to be + and predominantly > or = at 25% of the S wave, which characterized an rS type QRS deflection in both females and males. The general characteristics of the cardiac chambers in sloths are similar to those observe in other domestic and wild mammals. However, the presence of pectineal muscles associated with the atria and auricles differs from that observed in mammals such as the paca and raccoon and in birds such as the ostrich, which have trabecular structures in these cavities. The number of valves in sloths is equal to the anteater. However, it has a marginal trabeculae septum, not seen in Bradypus variegatus. According to the electrocardiographic findings, the rhythm was sinus, but much lower than that observed in the capuchin monkey, which also maintains arboreal habits.(AU)

Towards a standard framework to describe behaviours in the common-sloth (Bradypus variegatus Schinz, 1825): novel interactions data observed in distinct fragments of the Atlantic forest, Brazil / Contribuição para a padronização da descrição de comportamentos de preguiça-comum (Bradypus variegatus Schinz, 1825): novos dados de interação observados em distintos fragmentos de Mata Atlântica, Brasil

The common three-toed sloth is a widespread species, but the location and the observation of its individuals are greatly hindered by its biological features. Their camouflaged pelage, its slow and quiet movements, and the strictly arboreal habits resulted in the publication of sparse, fragmented and not patterned information on the common sloth behaviour. Thus, herein we propose an updated standardized behavioural categories' framework to the study of the species. Furthermore we describe two never reported interaction behaviours: a probable mating / courtship ritual between male and female; and apparent recognition behaviour between two males. Finally we highlight the contribution of small-duration field works in this elusive species ethological study.

A preguiça-de-três-dedos comum é uma espécie amplamente distribuída. No entanto, a biologia da espécie dificulta a sua deteção e observação na natureza. A camuflagem da sua pelagem, seus movimentos lentos e silenciosos e seus hábitos estritamente arbóreos resultaram na publicação de dados comportamentais esparsos, fragmentados e não padronizados. Assim, no presente trabalho propomos uma tabela atualizada e padronizada de comportamentos de preguiça-comum. Além disso, descrevemos dois novos comportamentos de interação para a espécie: um provável evento de corte ou acasalamento entre macho e fêmea e um aparente comportamento de reconhecimento entre dois machos. Finalmente, discutimos a contribuição de trabalhos de campo de curta-duração no estudo etológico desta espécie tão elusiva.

Temporal and spatial resource use by female three-toed sloths and their young in an agricultural landscape in Costa Rica

The information on ecological behavior of wild sloths is very scarce. In this study we determined the home ranges and resources used by three adult female three-toed sloths (Bradypus variegatus) and their four young in an agricultural matrix of cacao (Theobroma cacao), pasture, riparian forests and living fencerows in Costa Rica. Births occurred during November-December and the young became independent at five to seven months of age. Initially, mothers remained fixed in one or a few trees, but expanded their use of resources as young sloths became independent from them. Mothers initially guided the young to preferred food and cover resources, but they gradually left their young in small nucleus areas and colonized new areas for themselves. Home range sizes for young sloths (up to seven months of age) varied between 0.04-0.6 hectares, while home range sizes for mothers varied from 0.04-25.0 hectares. During the maternal care period, 22 tree species were used, with the most common being Cecropia obtusifolia (30.9%), Coussapoa villosa (25.6%), Nectandra salicifolia (12.1%), Pterocarpus officinalis (5.8%) and Samanea saman (5.4%). However, young sloths used only 20 tree species, with the most common being C. villosa (18.4%), S. saman (18.5 %) and N. salicifolia (16.7%). The cacao agroforest was used only by mother sloths and never by their young following separation. However, in the riparian forest, both mother sloths and young used the tree species. A total of 28 tree species were used by the mother sloth; including the food species: C. obtusifolia, C. villosa, N. salicifolia and P. officinalis. However, the young used 18 trees species in this habitat with N. salicifolia and S. saman most commonly used, although they rested and fed during the day in C. obtusifolia, C. villosa and O. sinnuata. The cacao agroforest with adjacent riparian forests and fencerows provides an important habitat type that links the smaller secondary forests and other patches. Rev. Biol. Trop. 59 (4): 1743-1755. Epub 2011 December 01.

La información sobre el comportamiento ecológico de los perezosos silvestre es muy escasa. Determinamos los ámbitos de acción y uso de recursos para hembras adultas de perezosos de tres dedos (Bradypus variegatus) y sus crías en una matriz agroforestal compuesta de cacao (Theobroma cacao), potreros, bosques ribereños y cercas vivas en Costa Rica. Los nacimientos de las crías se presentan frecuentemente de noviembre a diciembre y entre 5 a 7 meses las crías se vuelven independientes. Inicialmente las madres utilizan pocos árboles y van expandiendo el uso de recursos conforme las crías se van haciendo independientes de la madre. Las madres en los primeros meses guían a sus crías para seleccionar recursos y coberturas de bosque preferidos, y gradualmente se van separando de la cría hasta dejarlos en lo que fue su área núcleo. Ámbitos de acción de las crías (de hasta 7 meses o más de edad) varían entre 0.04-0.6ha, mientras que los ámbitos de acción de las madres varían 0.04-25.0ha. Durante el cuido maternal, 22 especies de árboles fueron utilizadas entre las más comunes se encuentran: Cecropia obtusifolia (30.9%), Coussapoa villosa (25.6%), Nectandra salicifolia (12.1%), Pterocarpus officinalis (5.8%) y Samanea saman (5.4%). Los jóvenes utilizaron solo 20 especies entre las más comunes C. villosa (18.4%), S. saman (18.5 %) y N. salicifolia (16.7%). El sistema agroforestal del cacao fue únicamente utilizado por la madre y no por la cría después del periodo de separación. Sin embargo, en los bosques ribereños tanto la madre como la cría utilizaron árboles como recursos. Un total de 28 especies de árboles fueron utilizados por la madre incluyendo especies para su alimentación tales como: C. obtusifolia, C. villosa, N. salicifolia y P. officinalis. Los jóvenes solo utilizaron 18 especies de árboles como N. salicifolia and S. saman entre las más frecuentes; inclusive los árboles utilizados para descanso y alimentación durante el día fueron C. obtusifolia, C. villosa y O. sinnuata. Los sistemas agroforestales de cacao adyacentes a bosques ribereños y cercas vivas proveen un importante hábitat que une pequeños parches de bosques secundarios.

Fecal estradiol and progesterone metabolite levels in the three-toed sloth (Bradypus variegatus)

The present study was carried out to assess the possibility of measuring fecal steroid hormone metabolites as a noninvasive technique for monitoring reproductive function in the three-toed sloth, Bradypus variegatus. Levels of the estradiol (E2) and progesterone (P4) metabolites were measured by radioimmunoassay in fecal samples collected over 12 weeks from 4 captive female B. variegatus sloths. The validation of the radioimmunoassay for evaluation of fecal steroid metabolites was carried out by collecting 10 blood samples on the same day as defecation. There was a significant direct correlation between the plasma and fecal E2 and P4 levels (P < 0.05, Pearson's test), thereby validating this noninvasive technique for the study of the estrous cycle in these animals. Ovulation was detected in two sloths (SL03 and SL04) whose E2 levels reached 2237.43 and 6713.26 pg/g wet feces weight, respectively, for over four weeks, followed by an increase in P4 metabolites reaching 33.54 and 3242.68 ng/g wet feces weight, respectively. Interestingly, SL04, which presented higher levels of E2 and P4 metabolites, later gave birth to a healthy baby sloth. The results obtained indicate that this is a reliable technique for recording gonadal steroid secretion and thereby reproduction in sloths.

Electrocardiographic studies of the three-toed sloth, Bradypus variegatus

Electrocardiograms (ECG) obtained with standard limb leads and augmented unipolar limb leads were recorded from 17 unanesthetized adult sloths. The animals were held in their habitual position in an experimental chair. We determined heart rate and rhythm from the R-R intervals, the amplitude and duration of each wave, and the duration of the segments and intervals of the ECG. The mean electrical axes of P and T waves and QRS complex were calculated on the basis of the amplitude of these waves in leads I, II, III, aV R, aV L, and aV F. The P wave appeared positive in most tracings with low amplitude in lead II, the QRS complex was generally negative in leads aV R, III and aV F, and no arrhythmias were observed. With a mean ± SD heart rate for all recordings of 81 ± 18 bpm, the duration of P and T waves, QRS complex, and PR, QT and RR intervals averaged 0.05 ± 0.02, 0.15 ± 0.05, 0.07 ± 0.02, 0.13 ± 0.02, 0.38 ± 0.04, and 0.74 ± 0.17 s, respectively. The ECG shape had a definite configuration on each lead. The angles of the mean ± SD electrical axes for atrial and ventricular depolarization and ventricular repolarization in the horizontal plane were +34 ± 68°, -35 ± 63°, and -23 ± 68°, respectively. All electrical axes showed great variations and their mean values suggest that, when the sloth is in a seated position, the heart could be displaced by the diaphragm to a semi-horizontal position.

Sloth biology: an update on their physiological ecology, behavior and role as vectors of arthropods and arboviruses

This is a review of the research undertaken since 1971 on the behavior and physiological ecology of sloths. The animals exhibit numerous fascinating features. Sloth hair is extremely specialized for a wet tropical environment and contains symbiotic algae. Activity shows circadian and seasonal variation. Nutrients derived from the food, particularly in Bradypus, only barely match the requirements for energy expenditure. Sloths are hosts to a fascinating array of commensal and parasitic arthropods and are carriers of various arthropod-borne viruses. Sloths are known reservoirs of the flagellate protozoan which causes leishmaniasis in humans, and may also carry trypanosomes and the protozoan Pneumocystis carinii

An update on the physiology of two- and three-toed sloths

Physiological and pharmacological research undertaken on sloths during the past 30 years is comprehensively reviewed. This includes the numerous studies carried out upon the respiratory and cardiovascular systems, anesthesia, blood chemistry, neuromuscular responses, the brain and spinal cord, vision, sleeping and waking, water balance and kidney function and reproduction. Similarities and differences between the physiology of sloths and that of other mammals are discussed in detail