Hydrochoerus Hydrochaeris Linnaeus Research Articles

Anatomical study of the origin and distribution of the lumbosacral plexus and vertebral topography of the medullary cone in capybara (Hydrochoerus hydrochaeris Linnaeus, 1766)

Anatomical study of the origin and distribution of the lumbosacral plexus and vertebral topography of the medullary cone in capybara (Hydrochoerus hydrochaeris Linnaeus, 1766)

Distribution patterns and habitat preferences of medium and large mammals of the order Rodentia in the Carcarañá river basin, Southern Santa Fe province, Argentina

This contribution analyzes the distribution patterns and habitat preferences of wildlife in highly anthropized environments. Considering that the pampas grasslands are one of the most modified natural ecosystems in the world and that both the capybara (Hydrochoerus hydrochaeris Linnaeus, 1766) and the coypu (Myocastor coypus Molina, 1782) have historically been some of the most characteristic mammals of this ecosystem, it is from these two species that the environmental variables that best explain their distribution and affectation will be analyzed.

Multi-elemental exposure assessment through concentrations in hair of free-ranging capybaras (Hydrochoerus hydrochaeris Linnaeus, 1766) in the Atlantic Forest remnants, Northeast of Brazil

This study aimed to determine the mineral profile of hair samples of free-ranging capybaras (Hydrochoerus hydrochaeris) in remnants of the Atlantic Forest located in the Northeast of Brazil, and to evaluate the effects of origin, gender and age of the animals on their mineral accumulation in hair. Twenty hair samples from animals of different areas, genders and ages were prepared using microwave-assisted digestion, employing 5 mL of HNO3 and 2.5 mL of H2SO4 for 100 mg of sample. Digestion efficiency was assessed by residual carbon content. The digested samples were analyzed by inductively coupled plasma optical emission spectrometry (ICP OES). Principal component analysis (PCA) was performed considering the composition data of 11 elements (Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mn, Mo, and Na). The digestion method applied was efficient and the most abundant elements with their respective concentration ranges in mg kg−1 were Al (396–2746), Ca (36–3420), Fe (476–51180), K (115–4843), and Na (72–473). ANOVA and PCA differentiated among the capybaras regarding age (adults) and origin (A3), both associated with higher concentrations of Al, Cd, Fe, and K. Although a higher metal bioaccumulation was observed in adult animals, it is important to highlight that this result could have been affected by diet and physiological parameters. The results suggest that A3 was the most anthropized remnant area due to agricultural and urban influences. Multi-elemental determination in hair can be used as a non-invasive method to assess heavy metal contamination in capybaras.

Rickettsia rickettsii (Rickettsiales: Rickettsiaceae) Infecting Amblyomma sculptum (Acari: Ixodidae) Ticks and Capybaras in a Brazilian Spotted Fever-Endemic Area of Brazil.

The bacterium Rickettsia rickettsii is the agent of Brazilian spotted fever (BSF), a highly fatal disease that is transmitted in Brazil mainly by the tick Amblyomma sculptum Berlese, which uses capybaras (Hydrochoerus hydrochaeris Linnaeus) as major hosts. In 2015, we captured nine capybaras in a BSF-endemic area of southeastern Brazil. From each capybara, we collected blood sera that were tested through the immunofluorescence assay using Rickettsia spp. antigens, and A. sculptum ticks, processed for isolation of R. rickettsii through guinea pig inoculation. All capybaras (100%) were seroreactive to Rickettsia spp., with highest titers to R. rickettsii. A total of 166 A. sculptum ticks were macerated and inoculated into nine guinea pigs, from which only one presented high fever and seroconverted to R. rickettsii. Blood from this febrile animal was inoculated into additional guinea pigs (guinea pig passages), which also became febrile and seroconverted, or when euthanized during the fever period, their internal organs (spleen, lung) were shown to contain R. rickettsii DNA. The present rickettsial isolate has been maintained cryopreserved as infected guinea pig organs. There was at least one R. rickettsii-infected tick among the 166 macerated ticks, giving a minimal infection rate of 0.6% (1/166). This infection rate is within the range of previous studies, which reported that only 0.05% to at most 1.28% A. sculptum ticks were infected by R. rickettsii in other BSF-endemic areas. These low infection rates support the low incidence of BSF, despite of A. sculptum being the most frequent human-biting tick in southeastern Brazil.

Evaluation of rickettsial infection in free-range capybaras (Hydrochoerus hydrochaeris Linnaeus, 1766) (Rodentia: Caviidae) and ticks (Acari: Ixodidae) in the Western Amazon, Brazil

Capybaras (Hydrochoerus hydrochaeris Linnaeus, 1766) (Rodentia: Caviidae) are important hosts of Amblyomma ticks (Acari: Ixodidae), which in turn can transmit rickettsiae to humans and animals. However, there is a scarcity of studies about the tick fauna and rickettsial infection in the Amazon region. The present study evaluated rickettsial infection in capybaras and ticks in different areas of the municipality of Rio Branco, state of Acre, in the Western Brazilian Amazon, where rickettsiosis has never been reported. Blood sera from 43 capybaras from four localities in Rio Branco were tested by indirect immunofluorescence assay using Rickettsia rickettsii antigens. Ticks were collected from capybaras and from vegetation as well. Ticks were taxonomically identified to the species level and some of them were tested by PCR, targeting a fragment of the rickettsial gltA gene. Additionally, ticks were tested for bacteria from the genus Borrelia and family Anaplasmatacae. All capybaras submitted to the serological examination were considered non-reactive to R. rickettsii. A total of 410 ticks were collected directly from the capybaras. Amblyomma dubitatum Neumann, 1899 was the most abundant species (82.4%), followed by Amblyomma naponense (Packard, 1869) (14.3%), Amblyomma humerale Koch, 1844 (0.7%), Amblyomma pacae Aragão, 1911 (0.4%), Amblyomma rotundatum Koch 1844 (0.2%) and Amblyomma sp. (1.7%). From the environment 262 ticks were collected: Rhipicephalus microplus (Canestrini, 1888) (88.9%), Dermacentor nitens Neumann, 1897 (9.9%), Amblyomma varium Koch, 1844 (0.7%) and A. rotundatum (0.3%). With the exception of A. humerale, A. rotundatum and R. microplus, all other species are reported here for the first time in the state. Some of the ticks sampled (N = 317) were tested by molecular methods for infection by Rickettsia spp. Rickettsia bellii was identified infecting A. dubitatum and A. rotundatum, while Rickettsia amblyommatis only was found infecting A. humerale and Rickettsia sp. strain Tapirapé was found in A. naponense. This is the first detection of R. bellii and Rickettsia sp. strain Tapirapé in Acre. No Borrelia or Anaplasmataceae were found in the tested ticks. These results add relevant knowledge about the Rickettsia spp. and the acarological fauna in the region of the Western Amazon, and are essential for the maintenance of vigilance about possible pathogens that occur in the state and determination of the risks that they pose to humans and animals that inhabit the region.

Description of the terminal branches of the abdominal aorta in capybaras Hydrochoerus hydrochaeris Linnaeus, 1766 (Mammalia: Rodentia)

The capybara Hydrochoerus hydrochaeris Linnaeus, 1766 (Mammalia: Rodentia) is the largest rodent in the world, with great economic potential. Exceeding 80 kg, the animal always lives close to water bodies and its hierarchical flocks have a single dominant male. Current study analyzes the structure and positioning of the terminal branches of the capybara's abdominal aorta to identify clinical pathologies, surgical and radiological procedures, and to contribute towards the knowledge of the rodent's anatomy. The abdominal aorta and its final branches (internal iliac artery, external iliac artery and median sacral artery) of six animals were dissected. Results showed that the organs were very similar to those registered in the literature for other species of rodents.

Reproductive performance of capybaras (Hydrochoerus hydrochaeris) in captivity under different management systems in Argentina

The capybara (Hydrochoerus hydrochaeris Linnaeus, 1766) is a wild rodent of great eco- nomic interest and is easily domesticated. Variations in reproductive parameters for the capybaras depend on both intrinsic and extrinsic factors, which modulate the different stages of its reproduc- tion either in captivity or wildlife. In captivity, an intensive production system is feasible, offering an economical profit under certain reproductive conditions. This work evaluates the reproductive performance of capybaras under different management systems in captivity, interpreting the results biologically and giving management guidelines to optimize their intensive production. The study was carried out at the Capybara Breeding Station, located in the Agricultural Experimental Station Delta del Parana, belonging to the National Institute for Agricultural Technology (INTA; Cam- pana, province of Buenos Aires, Argentina; 34 ◦ 08'S; 58 ◦ 12'W), from August 1997 to December 1998. Three different management systems were tested: System I Isolated pens (IP), composed of three different types of outdoor enclosures for reproduction, and growth. System II Isolated females (IM), formed by a central enclosure (reproduction pen), communicating with 12 paddocks (maternity pen) and growth pens. System III Mixed pens (MP), an enclosure of 35 × 10-m divided in area and maternity pens; the offspring were moved to growth pens elsewhere. A temporary weaning technique was tested for the mixed pens system. The variables analyzed for all systems were litter size at birth and at weaning, nursing and interbirth periods, and survival rates (at birth, weaning and total). The reproductive efficiency of each adult female was calculated as the total number of individuals weaned alive in a one-year period. During the study, 348 young were born in 104 births, from a total of 59 adult females. We conclude that the system that performs the best for capybara reproduction is the mixed pens system, including tem- porary weaning. Under this management strategy the following parameters were registered: mean litter size of 3.8 newborn per birth; 85% of live offspring at weaning; two births per year per female; all resulting in a reproductive efficiency of 6.5 young weaned alive per year × female. These repro- ductive parameters provide the necessary conditions to obtain economical profit of captive-bred capybaras. breeding management / capybara / captivity / production / reproduction