Microbial experience through housing in a farmyard-type environment alters intestinal barrier properties in mouse colons.

To close the gap between ultra-hygienic research mouse models and the much more environmentally exposed conditions of humans, we have established a system where laboratory mice are raised under a full set of environmental factors present in a naturalistic, farmyard-type habitat-a process we have called feralization. In previous studies we have shown that feralized (Fer) mice were protected against colorectal cancer when compared to conventionally reared laboratory mice (Lab). However, the protective mechanisms remain to be elucidated. Disruption of the protective intestinal barrier is an acknowledged player in colorectal carcinogenesis, and in the current study we assessed colonic mucosal barrier properties in healthy, feralized C57BL/6JRj male mice. While we found no effect of feralization on mucus layer properties, higher expression of genes encoding the mucus components Fcgbp and Clca1 still suggested mucus enforcement due to feralization. Genes encoding other proteins known to be involved in bacterial defense (Itln1, Ang1, Retnlb) and inflammatory mechanisms (Zbp1, Gsdmc2) were also higher expressed in feralized mice, further suggesting that the Fer mice have an altered intestinal mucosal barrier. These findings demonstrate that microbial experience conferred by housing in a farmyard-type environment alters the intestinal barrier properties in mice possibly leading to a more robust protection against disease. Future studies to unravel regulatory roles of feralization on intestinal barrier should aim to conduct proteomic analyses and in vivo performance of the feralized mice intestinal barrier.

Oogenic development and gonotrophic cycle of Aedes aegypti and Aedes albopictus in laboratory / Desarrollo oogénico y ciclo gonotrófico de Aedes aegypti y Aedes albopictus en laboratorio

Abstract: Objective: To determine the time of oogenic development and the length of the gonotrophic cycle of Ae. aegypti and Ae. albopictus in laboratory. Materials and methods: Bloodfed females of Ae. aegypti and Ae. albopictus were dissected every 4 h to determine the development status of the follicles according to the Christophers' stages. Results: The minimum time of oocyte maturation in Ae. aegypti and Ae. albopictus was 64-82 h and 52-64 h post-feeding, respectively. We found that the gonotrophic cycle of Ae. aegypti (3.7-4.2 d) is longer than that of Ae. albopictus (3.2-3.7 d). The follicle length showed significant differences between species at Christophers' stages 2" and 5, whereas follicle amplitude was different between the two mosquitoes at stages 2", 3 and 4. Conclusions: The study provided new evidence on the reproductive strategies of Ae. aegypti and Ae. albopictus females that coexist in the Neotropical region of Mexico.

Resumen: Objetivo: Determinar el tiempo de desarrollo oogénico y del ciclo gonotrófico de Aedes aegypti y Aedes albopictus en laboratorio. Material y métodos: Hembras de Ae. aegypti y Ae. albopictus alimentadas con sangre fueron disecadas cada cuatro horas para determinar el estado de desarrollo folicular, según los estadios de Christophers. Resultados: El tiempo mínimo de maduración del oocito en Ae. aegypti y Ae. albopictus fue de 64-82 h y 52-64 h post-alimentación, respectivamente. El ciclo gonotrófico de Ae. aegypti (3.7-4.2 d) fue mayor que el de Ae. albopictus (3.2-3.7 d). La longitud folicular presentó diferencias significativas entre las especies en los estadios de Christophers 2" y 5, mientras que la amplitud folicular fue diferente entre ambos mosquitos en los estadios 2", 3 y 4. Conclusiones: El estudio proporcionó nueva evidencia sobre la estrategia reproductiva de las hembras de Ae. aegypti y Ae. albopictus que coexisten en la región neotropical de México.

Towards a fully automated surveillance of well-being status in laboratory mice using deep learning: Starting with facial expression analysis.

Assessing the well-being of an animal is hindered by the limitations of efficient communication between humans and animals. Instead of direct communication, a variety of parameters are employed to evaluate the well-being of an animal. Especially in the field of biomedical research, scientifically sound tools to assess pain, suffering, and distress for experimental animals are highly demanded due to ethical and legal reasons. For mice, the most commonly used laboratory animals, a valuable tool is the Mouse Grimace Scale (MGS), a coding system for facial expressions of pain in mice. We aim to develop a fully automated system for the surveillance of post-surgical and post-anesthetic effects in mice. Our work introduces a semi-automated pipeline as a first step towards this goal. A new data set of images of black-furred laboratory mice that were moving freely is used and provided. Images were obtained after anesthesia (with isoflurane or ketamine/xylazine combination) and surgery (castration). We deploy two pre-trained state of the art deep convolutional neural network (CNN) architectures (ResNet50 and InceptionV3) and compare to a third CNN architecture without pre-training. Depending on the particular treatment, we achieve an accuracy of up to 99% for the recognition of the absence or presence of post-surgical and/or post-anesthetic effects on the facial expression.

Continuous measurement of locomotor activity during convalescence and acclimation in group-housed rats.

Locomotor activity is affected by a range of factors in addition to experimental treatment, including the breeding environment. Appropriate convalescence and acclimation are important for animal experiments, because environmental changes and physical burden can result from surgery, transportation, and cage exchange. However, the duration that locomotor activity is affected by these factors is currently unclear, because it has traditionally been difficult to measure locomotor activity in multiple group-housed animals in any location other than the analysis room. In the present study, we analyzed the locomotor activity of group-housed rats using a nano tag® after surgery, transportation, and cage exchange. The nano tag®, a new device for analyzing activity, can measure locomotor activity in laboratory animals with no limitation on the number of animals in same cage. Any type of cage can be used for analysis, at any time of day, and in any location. Nano tags® were subcutaneously implanted in male rats (F344/NSlc, 6 weeks of age) and locomotor activity was continuously measured after surgery, transportation, and cage exchange. Significant activity changes were observed in rats after transportation and cage exchange, 9 days and 3 h after the event, respectively. The results suggest that continuous measurement of locomotor activity with nano tags® can be used to monitor changes in activity induced by environmental changes, and will be helpful for designing animal experiments analyzing locomotor activity.

Pain and Laboratory Animals: Publication Practices for Better Data Reproducibility and Better Animal Welfare.

Scientists who perform major survival surgery on laboratory animals face a dual welfare and methodological challenge: how to choose surgical anesthetics and post-operative analgesics that will best control animal suffering, knowing that both pain and the drugs that manage pain can all affect research outcomes. Scientists who publish full descriptions of animal procedures allow critical and systematic reviews of data, demonstrate their adherence to animal welfare norms, and guide other scientists on how to conduct their own studies in the field. We investigated what information on animal pain management a reasonably diligent scientist might find in planning for a successful experiment. To explore how scientists in a range of fields describe their management of this ethical and methodological concern, we scored 400 scientific articles that included major animal survival surgeries as part of their experimental methods, for the completeness of information on anesthesia and analgesia. The 400 articles (250 accepted for publication pre-2011, and 150 in 2014-15, along with 174 articles they reference) included thoracotomies, craniotomies, gonadectomies, organ transplants, peripheral nerve injuries, spinal laminectomies and orthopedic procedures in dogs, primates, swine, mice, rats and other rodents. We scored articles for Publication Completeness (PC), which was any mention of use of anesthetics or analgesics; Analgesia Use (AU) which was any use of post-surgical analgesics, and Analgesia Completeness (a composite score comprising intra-operative analgesia, extended post-surgical analgesia, and use of multimodal analgesia). 338 of 400 articles were PC. 98 of these 338 were AU, with some mention of analgesia, while 240 of 338 mentioned anesthesia only but not post-surgical analgesia. Journals' caliber, as measured by their 2013 Impact Factor, had no effect on PC or AU. We found no effect of whether a journal instructs authors to consult the ARRIVE publishing guidelines published in 2010 on PC or AC for the 150 mouse and rat articles in our 2014-15 dataset. None of the 302 articles that were silent about analgesic use included an explicit statement that analgesics were withheld, or a discussion of how pain management or untreated pain might affect results. We conclude that current scientific literature cannot be trusted to present full detail on use of animal anesthetics and analgesics. We report that publication guidelines focus more on other potential sources of bias in experimental results, under-appreciate the potential for pain and pain drugs to skew data, and thus mostly treat pain management as solely an animal welfare concern, in the jurisdiction of animal care and use committees. At the same time, animal welfare regulations do not include guidance on publishing animal data, even though publication is an integral part of the cycle of research and can affect the welfare of animals in studies building on published work, leaving it to journals and authors to voluntarily decide what details of animal use to publish. We suggest that journals, scientists and animal welfare regulators should revise current guidelines and regulations, on treatment of pain and on transparent reporting of treatment of pain, to improve this dual welfare and data-quality deficiency.

Sexual maturation of the Mongolian gerbil (Meriones unguiculatus): a histological, hormonal and spermatic evaluation.

This study determined the phases of sexual development of the male Mongolian gerbil (Meriones unguiculatus) based on an integrative analysis of testicular morphology, hormonal data and sperm parameters. Male gerbils were analysed at 1, 7, 14, 21, 28, 35, 42, 50, 60, 70, 90, 100 and 120 days of age. Body, testicular and epididymal weights increased up to Day 70, 60 and 90, respectively. The impuberal phase, characterised by the presence of gonocytes, extended until Day 14. The prepubertal period lasted until Day 42, when puberty was achieved and a drastic increase in serum testosterone levels, mature adult Leydig cells and elongated spermatids was observed. Gerbils at 60 days of age showed a remarkable number of spermatozoa in the testis, epididymidis caput/corpus and cauda, and at Day 70 the maximum daily sperm production was reached. However, the gerbil may be considered sexually mature only from Day 90 onward, when sperm reserves become stable. The total transit time of spermatozoa along the epididymis of sexually mature gerbils was 11 days, with 1 day in the caput/corpus and 10 days in the cauda. These data cover a lacuna regarding the reproductive parameters of this rodent and provide foundations for its use in testicular toxicology studies.

Improvement of gamete quality and its short-term storage: an approach for biotechnology in laboratory fish.

In fish, in vitro fertilization is an important reproductive tool used as first step for application of others biotechniques as chromosome and embryo manipulation. In this study, we aimed to optimize gamete quality and their short-term storage from the yellowtail tetra Astyanax altiparanae, for future application in laboratory studies. Working with sperm, we evaluated the effects of spawning inducers (carp pituitary gland and Ovopel® [(D-Ala6, Pro9-NEt) - mGnRH+metoclopramide]) and the presence of female on sperm motility. Additionally, we developed new procedures for short-term storage of sperm and oocytes. Briefly, sperm motility was higher when male fish were treated with carp pituitary gland (73.1 ± 4.0%) or Ovopel® (79.5 ± 5.5%) when compared with the control group treated with 0.9% NaCl (55.6 ± 27.2%; P=0.1598). Maintenance of male fish with an ovulating female fish also improved sperm motility (74.4 ± 7.4%) when compared with untreated male fish (42.1 ± 26.1%; P=0.0018). Storage of sperm was optimized in modified Ringer solution, in which the sperm was kept motile for 18 days at 2.5°C. The addition of antibiotics or oxygen decreased sperm motility, but partial change of supernatant and the combination of those conditions improve storage ability of sperm. Fertilization ability of oocytes decreased significantly after storage for 30, 60 90 and 120 min at 5, 10, 15 and 20°C when compared with fresh oocytes (P=0.0471), but considering only the stored samples, the optimum temperature was 15°C. Those data describe new approaches to improve semen quality and gametes short-term storage in yellowtail tetra A. altiparanae and open new possibilities in vitro fertilization.

Reproduction of Omalonyx matheroni (Gastropoda: Succineidae) under laboratory conditions

The life histories of succineids have received relatively little attention. To evaluate life history characteristics of Omalonyx matheroni, we studied a Brazilian population (Reserva Particular do Patrimônio Natural Feliciano Miguel Abdala, in Caratinga, Minas Gerais, Brazil) under laboratory conditions. The aims of the present study were (1) to describe in detail an appropriate rearing method; (2) to investigate the effects of different temperature and photoperiod conditions; and (3) to assess the effects of self and cross-fertilization on the reproductive biology of these mollusks. We studied the oviposition site, the time to sexual maturity and the influences of photoperiod and temperature on reproductive parameters of O. matheroni reared under laboratory conditions. We tested three combinations of temperature and photoperiod, designated A, B and C (A: 25ºC, 24 hours of light; B: environmental conditions of temperature and photoperiod, characterized as follows: average máximum temperature=27.1ºC, average minimum temperature=18.3ºC, average day length=12.06 hours; and C: 25ºC, zero hours of light) and two rearing densities (I: isolated and G: grouped) on reproductive parameters (number of eggs per egg mass, number of unviable eggs per mass, egg mass incubation period, and duration of the hatching period). A total of 186 individuals and 565 egg masses were studied. Data were analyzed by Student’s t-test, two-way ANOVA and Chi-Square test. Eight generations were produced (March/2004-March/2006), from 35 field specimens, 91% of 3 197 eggs hatched. The time to sexual maturity was approximately three months for individuals reared in groups or in isolation (Student’s t-test: t=1.41, df=31, p=0.16); however, they differed significantly in weight (Student’s t-test: t=3.6, df=31, p<0.001). Regarding the influences of temperatura and photoperiod on reproductive parameters, under natural environmental conditions, individuals produced a greater number of eggs per mass (ANOVA: F2,573=84.15, p<0.001), with a longer incubation period (ANOVA: F2;559=170.05, p<0.001). The extreme photoperiod conditions of 24 hours of light or zero hours of light likely imposed stress and could be related to the significant reductions in the number of eggs per mass, and egg incubation period as well as the increased synchrony in egg hatching. No correlations were observed between the number of unviable eggs per mass and the temperature, photoperiod (ANOVA: F2,573=0.87, p=0.92) or rearing density (ANOVA: F1,573=0.21, p=0.64). Individuals reared in isolation under natural conditions produced more eggs per mass and did not presented any disadvantage with respect to the variables analyzed as compared to the animals reared in groups. These results indicate that O. matheroni can successfully reproduce by selfing. Rev. Biol. Trop. 60 (2): 553-566. Epub 2012 June 01.

Electroencephalogram-based anaesthetic depth monitoring in laboratory animals.

Objective measurements of physiological parameters controlled by the autonomic nervous system such as blood pressure, heart rate and respiration are easily obtained nowadays during anaesthesia by the use of monitors: oscillometers, pulseoximeters, electrocardiograms and capnographs are available for laboratory animals. However, the effect-site of hypnotic drugs that cause general anaesthesia is the central nervous system (the brain). In the present, the adjustment of hypnotic drugs in veterinary anaesthesia is performed according to subjective evaluation of clinical signs which are not direct reflexes of anaesthetic effects on the brain, making depth of anaesthesia (DoA) assessment a complicated task. The difficulties in assessing the real anaesthetic state of a laboratory animal may not only result in welfare-threatening situations, such as awareness and pain sensation during surgery, but also in a lack of standardization of experimental conditions, as it is not easy to keep all animals from an experiment in the same DoA without a measure of anaesthetic effect. A direct measure of this dose-effect relationship, although highly necessary, is still missing in the veterinary market. Meanwhile, research has been intense in this subject and methods based on the brain electrical activity (electroencephalogram) have been explored in laboratory animal species. The objective of this review is to explain the achievements made in this topic and clarify how far we are from an objective measure of DoA for animals.

Direct effects of arsenic trioxide on action potentials in isolated cardiac tissues: importance of the choice of species, type of cardiac tissue and perfusion time.

INTRODUCTION: The aim of the present study was to evaluate direct/acute effects of arsenic trioxide on action potentials (APs) in isolated cardiac tissues, and to investigate if the choice of species and tissue and the duration of the perfusion play a role in arsenic-induced acute/direct prolongation of AP/QT. METHODS AND RESULTS: Direct electrophysiological effects of arsenic trioxide were measured in cardiac tissues isolated from four different species using micro-electrode recording. Arsenic (after 30 to 95 min perfusion at 10 µM) significantly prolonged APD(90), increased triangulation of the AP and elicited early afterdepolarizations (EADs) only in isolated guinea-pig and dog Purkinje fibers but not in rabbit and porcine (minipig) Purkinje fibers. Arsenic induced a prolongation of the APD(90) and increases in triangulation and the occurrence of EADs was not observed in papillary muscles of guinea-pigs and rabbits. Arsenic at 4 increasing concentrations from 0.1 µM to 10 µM at the standard perfusion-time of 15 min per concentration, and after a continuous 90-min perfusion at 1 µM and 1 Hz did not induce these direct effects on APD(90), triangulation and EADs in isolated guinea-pig Purkinje fibers, but it at 1 µM elicited EADs in 2 out of 7 preparations after 90 min at 0.2 Hz. DISCUSSION: The present study demonstrates that the choice of species and cardiac tissue as well as perfusion-time play important roles in arsenic-induced direct/acute effects on APD(90) and induction of EADs in vitro.

Eliminating animal facility light-at-night contamination and its effect on circadian regulation of rodent physiology, tumor growth, and metabolism: a challenge in the relocation of a cancer research laboratory.

Appropriate laboratory animal facility lighting and lighting protocols are essential for maintaining the health and wellbeing of laboratory animals and ensuring the credible outcome of scientific investigations. Our recent experience in relocating to a new laboratory facility illustrates the importance of these considerations. Previous studies in our laboratory demonstrated that animal room contamination with light-at-night (LAN) of as little as 0.2 lx at rodent eye level during an otherwise normal dark-phase disrupted host circadian rhythms and stimulated the metabolism and proliferation of human cancer xenografts in rats. Here we examined how simple improvements in facility design at our new location completely eliminated dark-phase LAN contamination and restored normal circadian rhythms in nontumor-bearing rats and normal tumor metabolism and growth in host rats bearing tissue-isolated MCF7(SR(-)) human breast tumor xenografts or 7288CTC rodent hepatomas. Reducing LAN contamination in the animal quarters from 24.5 ± 2.5 lx to nondetectable levels (complete darkness) restored normal circadian regulation of rodent arterial blood melatonin, glucose, total fatty and linoleic acid concentrations, tumor uptake of O(2), glucose, total fatty acid and CO(2) production and tumor levels of cAMP, triglycerides, free fatty acids, phospholipids, and cholesterol esters, as well as extracellular-signal-regulated kinase, mitogen-activated protein kinase, serine-threonine protein kinase, glycogen synthase kinase 3ß, γ-histone 2AX, and proliferating cell nuclear antigen.

Analgesic effects of meloxicam, morphine sulfate, flunixin meglumine, and xylazine hydrochloride in African-clawed frogs (Xenopus laevis).

We evaluated analgesic use and analgesiometry in aquatic African-clawed frogs (Xenopus laevis). We used the acetic acid test (AAT) to assess the analgesic potential of systemic xylazine hydrochloride, meloxicam, flunixin meglumine, and morphine sulfate after injection into the dorsal lymph sac. Flunixin meglumine provided better analgesia than did the other drugs, most evident at 5 and 9 h after administration. Because the AAT was associated with the development of dermal lesions, we discontinued use of this assay and chose the Hargreaves test as an alternative method of measuring nociception in Xenopus. This assay is commonly performed in rodents, but its efficacy in an aquatic species such as Xenopus was unknown prior to this study. We found that the Hargreaves test was an effective measure of nociception in Xenopus, and we used it to evaluate the effectiveness of the nonopiod agents xylazine hydrochloride, meloxicam, and flunixin meglumine both in the absence of surgery and after surgical oocyte harvest. Similar to findings from the AAT, flunixin meglumine provided better analgesia in the Hargreaves test than did the other agents when analyzed in the absence of surgical intervention. Results were equivocal after oocyte harvest. Although surgical oocyte harvest is a common procedure in Xenopus, and currently there are no published recommendations for analgesia after this invasive surgery. Future studies are needed to clarify the efficacy of nonsteroidal antiinflammatory drugs for that purpose.

Effects of wire-bottom caging on heart rate, activity and body temperature in telemetry-implanted rats.

Some experimental procedures are associated with placement of animals in wire-bottom cages. The goal of this study was to evaluate stress-related physiological parameters (heart rate [HR], body temperature [BT], locomotor activity [LA], body weight [BW] and food consumption) in rats under two housing conditions, namely in wire-bottom cages and in bedding-bottom cages. Telemetry devices were surgically implanted in male Sprague-Dawley rats. HR, BT and LA were recorded at 5 min intervals. Analysis under each housing condition was performed from 16:00 to 08:00 h of the following day (4 h light, 12 h dark). During almost all of the light phase, the HR of rats housed in wire-bottom cages remained high (371 ± 35 bpm; mean ± SD; n = 6) and was significantly different from that of rats housed in bedding-bottom cages (340 ± 29 bpm; n = 6; P < 0.001; Student's t-test). In general, BT was similar under the two housing conditions. However, when rats were in wire-bottom cages, BT tended to fluctuate more widely during the dark phase. LA decreased when animals were housed in wire-bottom cages, in particular during the dark phase. Moreover, there was a significant difference with respect to the gain in BW: BW of rats housed in bedding-bottom cages increased 12 ± 2 g, whereas that of rats in wire-bottom cages decreased by 2 ± 3 g (P < 0.001). Our results demonstrate that housing rats in wire-bottom cages overnight leads to immediate alterations of HR, BW and LA, which might be related to a stress response.

Behavioral and activity assessment of laboratory mice (Mus musculus) after tail biopsy under isoflurane anesthesia.

Contemporary laboratory animal guidance suggests that tail biopsy of laboratory mice can be performed before 21 d of age without anesthesia, whereas older mice must receive anesthesia before biopsy. Our objective was to determine whether administration of isoflurane anesthesia before tail biopsy produced a measurable effect on the behavior of mice (n = 196). We evaluated C57BL/6 and BALB/c mice at 21 to 24 (weaning), 28 to 31 (delayed weaning), and 42 to 45 (adult) d of age. Mice were observed at the time of biopsy and then twice within the first hour after a sham or tail biopsy. Anxiety-like responses were assessed by using an elevated plus-maze. Activity was evaluated remotely for 120 min. Isoflurane did not diminish acute responses to tail biopsy in mice 31 d or younger compared with sham-biopsied animals but had a significant effect in C57BL/6 biopsied adult mice. In addition, mice of all ages and strains that received anesthesia, regardless of biopsy, spent more time in the enclosed maze arms and had decreased activity up to 5 h after isoflurane exposure. Although tail biopsy should be performed in young mice to avoid transection of distal mature vertebrae, our experimental paradigm indicates that isoflurane anesthesia does not appreciably enhance wellbeing over that of mice biopsied without anesthesia at weaning ages. The influence of inhaled isoflurane was demonstrable and indicated that acute and prolonged alterations in anxiety and activity must be considered when interpreting the impact of anesthesia on tail biopsy across various ages and strains of laboratory mice.

Animais de laboratório: o camundongo / Laboratory animals: the mouse

A experimentação animal nas pesquisas científicas tem contribuído sobremaneira para o desenvolvimento da ciência e tecnologia, promovendo ao longo dos anos a descoberta de medidas profiláticas e tratamentos de enfermidades que acometem os seres humanos. Animais de várias espécies têm sido utilizados nos últimos tempos,sendo os camundongos os mais intensamente utilizados e os mais profundamente conhecidos cientificamente. O objetivo deste trabalho foi realizar um levantamento bibliográfico, incluindo os trabalhos do nosso grupo, sobre o emprego de camundongos na experimentação animal, abordando sua biologia geral, fisiologia de reprodução, sistemas de criação, genética, habitação, alimentação, manejo, dor e eutanásia, técnicas de risco desenvolvidas na experimentação, coleta de sangue, experimentos farmacológicos e toxicológicos. Embora tendências atuais preconizem a utilização de métodos alternativos (estudos in vitro, culturas de células, etc.), os modelos animais, como os camundongos, apresentam como principal vantagem o fornecimento de informações sobre o organismo como um todo, fato que não é conseguido com outros métodos, o que ainda possibilita o seu emprego em pesquisas científicas

The animal experimentation in the scientific research has contributed excessively for the development of science and technology, promoting to long of the years the discovery of prophylactic measures and treatments for iseases that attack the humans. Animals of some species have been used in the last times, being the mouse the more intensely used and more deeply known scientifically. The objective of this work was to carry through a bibliographical survey including data of our research group, about the use of mice in the animal experimentation, approaching its general biology, reproduction physiology, creation systems, genetics, habitation, feeding, handling, pain and euthanasia, techniques of risk developed in the experimentation, blood collection, pharmacological and toxicological experiments. Although current trends praise the use of alternative methods (in vitro studies, cells cultures, etc.), the animal models, as the mouse, present as main advantage the supply of information on the organism as a whole, fact that is not obtained with other methods, what still it makes possible its utilization in scientific research.

Issues to consider for preparing ferrets as research subjects in the laboratory.

The domestic or European ferret (Mustela putorius furo) has been domesticated for thousands of years. Ferrets have been used for hunting and fur production, as pets, and as models in biomedical research. Despite the relatively small numbers used in the laboratory, ferrets have some unique applications including study of human influenza and severe acute respiratory syndrome (SARS)-associated corona virus. They have served as models for peptic ulcer disease, carotenoid metabolism, cystic fibrosis, and drug emesis screening, among others. Most research ferrets are males, due to estrus-related health problems in females. They may be housed conventionally and are easy to care for when their biology and behavior are understood. Due to the small number of ferret suppliers, animals are often shipped long distances, requiring air transport and intermediate handlers. It is important to minimize shipment stress, especially with weanling and pregnant animals. Additional expertise is required for success with pregnant and whelping ferrets and for rearing of neonates. The animals have specific dietary requirements, and proper nutrition is key. Successful housing requires knowledge of ferret behaviors including social behavior, eating habits, a general inquisitive nature, and a species-typical need to burrow and hide. Regular handling is necessary to maintain well-being. A ferret health care program consists of physical examination, immunization, clinical pathology, and a working knowledge of common ferret diseases. Various research methodologies have been described, from basic procedures such as blood collection to major invasive survival surgery. Ferrets have a distinct niche in biomedical research and are hardy animals that thrive well in the laboratory.