Positive-reinforcement strategies to reduce capture-stress in Capybaras

Abstract

Prior to the administration of any anesthetics, capturing the semi-aquatic capybara (Hydrochoerus hydrochaeris) demands physical restraint, which presents immense challenges. Traditional methods, such as lassoing and traps, are prone to induce acute stress, may result in injury, and can even have fatal outcomes. As part of a larger population control project using contraceptive methods, frequent capture-induced stress and injury may directly affect normal reproductive physiology. Thus, choosing a less stress-inducing method was imperative. In this report, we describe methods of conditioning to enable frequent capture and manipulation, using bait as a positive reinforcement associated with a special clicksound, in a free-ranging population of 40 capybaras. The objectives were to attract, herd, and allow capybaras to voluntarily enter a coral. We evaluated the conditioning effect on individual and group behaviors, interpreting vocal and body language manifestations during the processes of conditioning, herding, capture, and recovery (post procedure/chemical restraint), with the aim of minimizing capturerelated stress and injuries. Based on our observations, we report that conditioning, used as part of the capture strategies, noticeably facilitated physical restraint and manipulation throughout the procedures, while apparently maintaining the animals' overall welfare as it relates to conditioning and capture.

Chemical immobilization of free-living capybaras (Hydrochoerus hydrochaeris) using ketamine-dexmedetomidine combination and a remote drug delivery system

“…Necropsy performed immediately at the location, an extreme dilation of the cecum, with evidence of ischemic mesentery and intestines was observed. The authors believe that the cause is of iatrogenic nature, brought about by several collective factors, including collateral anesthetic effects, absence of pre-anesthetic fasting, and high-sugary plants for baiting (Rosenfield et al, 2019). Similar observations have been reported in a number of studies and in varied species (Abutarbush et al, 2005;Colorado State University, 2019;Kümper, 1994;Tanila et al, 1993;Torjman et al, 2005;Zullian et al, 2011).…”

“…Allowing to be called and herded into the corral voluntarily, facilitating time-independent, frequent and selective capture (versus aleatory success), provoking less capture-induced stress, reducing the risk of injury (even death), while requiring lesser amounts of anesthetics, producing smoother recovery, and improving overall team safety. Furthermore, it allows conducting health exams and vital parameter evaluation, such as auscultation for the heart, -respiratory rate, and body temperature (Rosenfield & Schilbach Pizzutto, 2019).…”

“…Chemical immobilization of free-living (Hydrochoerus hydrochaeris) using ketamine-dexmedetomidine combination and a remote drug delivery system Only in anticipation and through constant monitoring heart rate, blood pressure, and respiratory rate, and percussion/palpation of the abdominal wall is it possible to identify tympany in time. Therefore, it is crucial to use sugary plants or fruits in very small quantities, just enough to draw attention (Rosenfield et al, 2019). Alternatively, less sugar-containing corn and banana leaves work quite well and are safer.…”

Gross Osteology and digital radiography of the common Capybara (Hydrochoerus hydrochaeris), Carl Linnaeus, 1766 for scientific and clinical application

“…As they become synanthropic wildlife (invading agricultural and urban areas with abundant high-caloric food sources), adults may weigh over 100 kg (Abreu Bovo, 2016;Rosenfield et al, 2019a). To control their super populations and combat the associated spread of zoonotic disease, as well as other human-wildlife conflicts, capybara has recently become the subject of several research projects (Luz et al, 2019;Passos Nunes et al, 2019;Rosenfield & Pizzutto, 2019;Rosenfield et al, 2019aRosenfield et al, , 2019bYanai & Cortopassi, 2020), or require medical attention due to injuries suffered during common human-capybara conflicts, as well as clinical care in zoos and parks around the world, and even as pets. Having a solid understanding of the anatomy of the wildlife species, particularly when working with them in the field, aids in the often-multidisciplinary research activities, including capture strategies by physical and chemical restraint, physical examination, and planning and performing clinical or surgical procedures.…”