Experimental evaluation of heat and moisture transfer in metal dog cage environments.

Dog cages with solid and expanded metal flooring were tested while unoccupied, occupied by a 10-kg adult male beagle, and occupied by simulated loads to represent a beagle and a greyhound. Cage performances were evaluated with no direct coupling between the room air supply and the cage, and with mechanical coupling of 50% and 100% of the room air supplied directly to the cage. At each of these conditions, the room was maintained at approximately 24 degrees C and 45% relative humidity with room air exchange rates of 5, 10, and 15 changes per hr. Results indicated significant differences existed in dry-bulb and dew-point temperatures between the cage and the room. These differences, together with significant vertical gradients of air velocity and dry-bulb and dew-point temperatures within the cage were shown to be affected by room air exchange rate, cage flooring, type of coupling, and cage load.     

A secure semi-field system for the study of Aedes aegypti

Background

New contained semi-field cages are being developed and used to test novel vector control strategies of dengue and malaria vectors. We herein describe a new Quarantine Insectary Level-2 (QIC-2) laboratory and field cages (James Cook University Mosquito Research Facility Semi-Field System; MRF SFS) that are being used to measure the impact of the endosymbiont Wolbachia pipientis on populations of Aedes aegypti in Cairns Australia.

Methodology/Principal Findings

The MRF consists of a single QIC-2 laboratory/insectary that connects through a central corridor to two identical QIC-2 semi-field cages. The semi-field cages are constructed of two layers of 0.25 mm stainless steel wire mesh to prevent escape of mosquitoes and ingress of other insects. The cages are covered by an aluminum security mesh to prevent penetration of the cages by branches and other missiles in the advent of a tropical cyclone. Parts of the cage are protected from UV light and rainfall by 90% shade cloth and a vinyl cover. A wooden structure simulating the understory of a Queenslander-style house is also situated at one end of each cage. The remainder of the internal aspect of the cage is covered with mulch and potted plants to emulate a typical yard. An air conditioning system comprised of two external ACs that feed cooled, moistened air into the cage units. The air is released from the central ceiling beam from a long cloth tube that disperses the airflow and also prevents mosquitoes from escaping the cage via the AC system. Sensors located inside and outside the cage monitor ambient temperature and relative humidity, with AC controlled to match ambient conditions. Data loggers set in the cages and outside found a <2°C temperature difference. Additional security features include air curtains over exit doors, sticky traps to monitor for escaping mosquitoes between layers of the mesh, a lockable vestibule leading from the connecting corridor to the cage and from inside to outside of the insectary, and screened (0.25 mm mesh) drains within the insectary and the cage. A set of standard operating procedures (SOP) has been developed to ensure that security is maintained and for enhanced surveillance for escaping mosquitoes on the JCU campus where the MRF is located. A cohort of male and female Aedes aegypti mosquitoes were released in the cage and sampled every 3–4 days to determine daily survival within the cage; log linear regression from BG-sentinel trapping collections produced an estimated daily survival of 0.93 and 0.78 for females and males, respectively.

Conclusions/Significance

The MRF SFS allows us to test novel control strategies within a secure, contained environment. The air-conditioning system maintains conditions within the MRF cages comparable to outside ambient conditions. This cage provides a realistic transitional platform between the laboratory and the field in which to test novel control measures on quarantine level insects.     

Evaluation of countermeasures for reduction of mouse airborne allergens

Three kinds of countermeasures for reduction of mouse airborne allergens were evaluated with use of an air sampler and immunochemical methods. Mouse cages and the sampler were placed inside a flexible-film isolator, and concentrations of mouse major allergens in the air were measured. The levels of the airborne allergens, prealbumin and albumin, generated by 10 males, were 3,050 and 492 pg/m3, respectively. Those by 10 females were lower, 317 and 270 pg/m3, respectively. When mouse cages were covered with a filter cap, the airborne allergens inside the isolator were decreased by 90%. When corncob was used as bedding in place of wood shavings, the airborne allergens were decreased by 57 and 77%, respectively. Therefore, for reduction of mouse airborne allergens, we recommend using female mice, covering the cages with filter caps, and using corncob bedding.     

The effects of different types of individually ventilated caging systems on growing male mice

Ventilation rate and turnover rate of dry air vary among different types of ventilation systems used with individually ventilated cages (IVCs) and can affect the well-being of rodents housed in these cages. The authors compared the effects of two types of IVC systems, forced-air IVCs and motor-free IVCs, on 4-week-old C57Bl/6J male mice. The mice were acclimatized to the cages for 8 d and then monitored for 87 d. Their body weights, food and water consumption and preferred resting areas were recorded. Mice that were housed in motor-free IVCs had a significantly greater increase in body weight than those housed in forced-air IVCs, despite having similar food consumption. Mice in forced-air IVCs had greater water consumption than mice in motor-free IVCs. In addition, mice in forced-air IVCs were more frequently located in the front halves of their cages, whereas mice in motor-free IVCs were located with similar frequency in the front and back halves of their cages, perhaps because of the higher ventilation rate or the location of the air inlets and outlets in the rear of the cage. These results suggest that body weight, food and water consumption and intracage location of growing male mice are influenced by the type of ventilation system used in the cages in which the mice are housed.     

Scrounging facilitates social learning in common marmosets, Callithrix jacchus

The minimalistic environment of standard laboratory cages can adversely influence the responses of animals in standard behavioural tests and other aspects of the animals' biology. To avoid this, cages should provide for the animals' species-specific behavioural characteristics. We hypothesized that, given their possible capacity for colour vision, laboratory mice, Mus musculus, would show preferences between cages of different colours. Studies show that environmental colour can influence emotionality and task performance in humans, suggesting that cage colour could also affect emotionality and performance of mice in behavioural tests. Seventy-two mice were housed in home cages painted red, black, green or white. Five weeks later, 24 mice were placed individually into an apparatus allowing them to choose between cages of each of the home cage colours. Each mouse showed a highly significant preference, which overall, was unrelated to home cage colour. White cages were most preferred and red were least. Home cage colour had a significant effect on body weight and food consumption as well as on behaviour in a raised plus maze. Mice from red home cages spent most time in the closed arms, indicating greater anxiety, possibly suggesting that the reduced occupancy of the red preference cages resulted from avoidance of environmental conditions that induced a negative mental state. These findings show that laboratory mice have strong preferences between cages of different colours. We also found that an apparently inconsequential environmental variable, home cage colour, can influence responses in standard behavioural tests, which should be considered in assessing the external validity of such tests. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.     

Barriers to flow: The effects of experimental cage structures on water velocities in high-energy subtidal and intertidal environments

For decades, marine ecologists have used cages as biological enclosure or exclosure devices to manipulate movement, growth, and survival of organisms. The ability to control the densities of focal organisms makes these structures a powerful tool. However, cages can often produce artifacts that influence the outcome of experiments. Although a subset of these artifacts have been examined previously, the effects of cages on water motion have not been adequately addressed from a quantitative standpoint, especially in high-flow environments. We targeted this data gap by explicitly measuring the fractional degree of velocity reduction inside a variety of experimental cage structures across flow conditions spanning those typical of wave-swept shallow subtidal and intertidal zones. Cages decreased velocities inside by up to 47% and reduced high-energy impact forces by more than 40%. Associated cage controls, employed to mimic physical effects of cages without interfering with organism movement, often had effects on water flow similar to those of cages. However, the nearly half an order of magnitude change in velocities inside cages and their controls reveals the need to be vigilant in considering potential artifacts, especially those tied to secondary biological interactions. These artifacts may be reduced by maximizing mesh size, employing large plot sizes and low profile structures, using cage controls that best mimic effects of the full cage, and monitoring cage controls to avoid the establishment of high-density “consumer hotels” within them. Using such approaches, researchers can minimize experimental biases and simplify the explanation of experimental results.     

New Ventilated Isolation Cage

A multifunction lid has been developed for a commercially available transparent animal cage which permits feeding, watering, viewing, long-term holding, and local transport of laboratory rodents on experiment while isolating the surrounding environment. The cage is airtight except for its inlet and exhaust high-efficiency particulate air filters, and it is completely steam-sterilizable. Opening of the cage's feed and water ports causes an inrush of high velocity air which prevents back-migration of aerosols and permits feeding and watering while eliminating need for chemical vapor decontamination. Ventilation system design permits the holding in adjacent cages of animals infected with different organisms without danger of cross-contamination; leaves the animal room odor-free; reduces required bedding changes to twice a month or less, and provides investigators with capability to control precisely individual cage ventilation rates. Forty-eight cages can be conveniently placed on a standard NIH "shoebox" cage rack (60 inches wide x 28 inches deep x 74 inches high) fitted with a simple manifold exhaust system. The entire system is mobile, requiring only an electrical power outlet. Principal application of the caging system is in the area of preventing exposure of animal caretakers to pathogenic substances associated with the animal host, and in reducing handling of animals and their exposure to extraneous contamination.     

Microbiological monitoring of laboratory mice and biocontainment in individually ventilated cages: a field study

Over recent years, the use of individually ventilated cage (IVC) rack systems in laboratory rodent facilities has increased. Since every cage in an IVC rack may be assumed to be a separate microbiological unit, comprehensive microbiological monitoring of animals kept in IVCs has become a challenging task, which may be addressed by the appropriate use of sentinel mice. Traditionally, these sentinels have been exposed to soiled bedding but more recently, the concept of exposure to exhaust air has been considered. The work reported here was aimed firstly at testing the efficiency of a sentinel-based microbiological monitoring programme under field conditions in a quarantine unit and in a multi-user unit with frequent imports of mouse colonies from various sources. Secondly, it was aimed at determining biocontainment of naturally infected mice kept in an IVC rack, which included breeding of the mice. Sentinels were exposed both to soiled bedding and to exhaust air. The mice which were used in the study carried prevalent infectious agents encountered in research animal facilities including mouse hepatitis virus (MHV), mouse parvovirus (MPV), intestinal flagellates and pinworms. Our data indicate that the sentinel-based health monitoring programme allowed rapid detection of MHV, intestinal flagellates and pinworms investigated by a combination of soiled bedding and exhaust air exposure. MHV was also detected by exposure to exhaust air only. The IVC rack used in this study provided biocontainment when infected mice were kept together with non-infected mice in separate cages in the same IVC rack.     

The impact of reduced frequency of cage changes on the health of mice housed in ventilated cages

Our purpose in this investigation was to determine if we could reduce cage changing frequency without adversely affecting the health of mice. We housed mice at three different cage changing frequencies: 7, 14, and 21 days, each at three different cage ventilation rates: 30, 60 and 100 air changes per hour (ACH), for a total of nine experimental conditions. For each condition, we evaluated the health of 12 breeding pairs and 12 breeding trios of C57BL/6J mice for 7 months. Health was assessed by breeding performance, weanling weight and growth, plasma corticosterone levels, immune function, and histological examination of selected organs. Over a period of 4 months, we monitored the cage microenvironment for ammonia and carbon dioxide concentrations, relative humidity, and temperature one day prior to changing the cage. The relative humidity, carbon dioxide concentrations, and temperature of the cages at all conditions were within acceptable levels. Ammonia concentrations remained below 25 ppm (parts per million) in most cages, but, even at higher concentrations, did not adversely affect the health of mice. Frequency of cage changing had only one significant effect; pup mortality with pair matings was greater at the cage changing frequency of 7 days compared with 14 or 21 days. In addition, pup mortality with pair matings was higher at 30 ACH compared with other ventilation rates. In conclusion, under the conditions of this study, cage changes once every 14 days and ventilation rates of 60 ACH provide optimum conditions for animal health and practical husbandry.     

Uniform DC electric field exposure systems for mice and cats

In most previous 50/60-Hz experiments, subjects were placed in a dielectric cage and the electric field was applied from outside the cage. Although the field outside the cage was kept uniform in space and constant in time, the field inside the cage undergoes undesirable temporal and spatial variations. We have designed an electric-field exposure system that overcomes these problems by having a metal cage constitute a part of the field generating electrodes. The uniformity along the diameter of the cages for mice and cats are more than 84.2% and 74.3%, respectively.     

Effects of housing density on nasal pathology of breeding mice housed in individually ventilated cages

The 2011 edition of the Guide for the Care and Use of Laboratory Animals includes new recommendations for the amount of floor space that should be provided to breeding mice. When pairs or trios of continuously breeding mice are housed in shoebox cages, they may have less than this recommended amount of floor space. High housing densities may adversely affect animal health, for example, by compromising air quality inside the cage. Hence, some institutions are carefully reevaluating the microenvironments of breeding cages. The use of individually ventilated cages (IVCs) to house research mice allows for greater control over the quality of the cage microenvironment. The authors evaluated the microenvironments of shoebox cages in an IVC rack system housing breeding and non-breeding Swiss Webster mice. Ammonia concentrations were significantly higher in cages housing breeding trios with two litters. Histopathologic lesions attributable to inhaled irritants such as ammonia were found in mice housed in breeding pairs and trios. The authors conclude that the microenvironments of cages in an IVC rack system housing breeding pairs and trios may be detrimental to animal health.     

Design and construction of cage environments for air ion and electric field research

This report describes the design and construction of cage environments suitable for chronic exposures of large groups of mice to air ions and electric fields. These environments provide defined and reproducible ion densities, ion flux, DC electric fields, sound levels, air temperature and air quality. When used during a 2 year study, these cage environments served as a durable and reliable continuous exposure system. Three environmental chambers (cubicles) housed a total of 12 cages and provided control of air temperature, air purity and lighting. Exposure cages had grounded metal exterior walls, a plexiglass door and interior walls lined with formica. An internal isolated field plate supplemented with guard wires, energized with ca 1000 VDC, created about a 2 kV/m electric field at the grounded cage floor. Air ions resulted from the beta emission of sealed tritium foils mounted on the field plate. Cages provided high ion (1.3×10⁵ ions/cc), low ion (1.6×10³ ions/cc) and field only (ion depleted < 50 ions/cc) conditions for both polarities with similar electric fields in ionized and field only cages. Detailed mapping of the floor level ion flux using 100 cm² flat probes gave average fluxes of 880 fA cm^–2 in high ion cages and 10 fA cm^–2 in low ion cages. Whole body currents measured using live anesthethized mice in high ion cages averaged 104±63 pA. Both ion flux and whole body currents remained constant over time, indicating no charge accumulation on body fur or cage wall surfaces in this exposure system.     

New Ventilated Isolation Cage

A multifunction lid has been developed for a commercially available transparent animal cage which permits feeding, watering, viewing, long-term holding, and local transport of laboratory rodents on experiment while isolating the surrounding environment. The cage is airtight except for its inlet and exhaust high-efficiency particulate air filters, and it is completely steam-sterilizable. Opening of the cage''s feed and water ports causes an inrush of high velocity air which prevents back-migration of aerosols and permits feeding and watering while eliminating need for chemical vapor decontamination. Ventilation system design permits the holding in adjacent cages of animals infected with different organisms without danger of cross-contamination; leaves the animal room odor-free; reduces required bedding changes to twice a month or less, and provides investigators with capability to control precisely individual cage ventilation rates. Forty-eight cages can be conveniently placed on a standard NIH “shoebox” cage rack (60 inches wide × 28 inches deep × 74 inches high) fitted with a simple manifold exhaust system. The entire system is mobile, requiring only an electrical power outlet. Principal application of the caging system is in the area of preventing exposure of animal caretakers to pathogenic substances associated with the animal host, and in reducing handling of animals and their exposure to extraneous contamination.     

Primate Location Preference in a Double-Tier Cage: The Effects of Illumination and Cage Height

Nonhuman primates are frequently housed in double-tier arrangements with significant differences between the environments of the upper and lower-row cages. Although several studies have investigated whether this arrangement alters monkeys' behavior, no studies have addressed the two most notable differences, light and height, individually to determine their relative importance. This experiment examined how rhesus and long-tailed macaques allocated their time between the upper and lower-row cages of a 1-over-1 apartment module under different lighting conditions. In Condition A, monkeys' baseline degree of preference for the upper- and lower-row was tested. In Condition B, the lighting environment was reversed by limiting illumination in the upper-row cage and increasing illumination in the lower-row cage. In both conditions, monkeys spent more time in the upper-row cage, thus indicating a strong preference for elevation regardless of illumination. The amount of time that monkeys spent in the lower-row cage increased by 7% under reversed lighting, but this trend was not significant. These results corroborate the importance of providing captive primates with access to elevated areas.     

Exclusion size and material have minimal effects on stream benthic algae and macroinvertebrate colonization within submerged cages

Despite their widespread use in grazer–biofilm studies, stream exclusion cages have inherent physical properties that may alter benthic organism colonization and growth. We used laboratory studies and a field experiment to determine how exclusion cage design (size and material) alters light availability, water velocity, and benthic organism colonization. We measured light reduction by various plastic cage materials and flow boundary layer thickness across a range of exclusion cage sizes in the laboratory. We also deployed multiple exclusion cage designs based on commonly available materials into a second-order stream to assess algae and macroinvertebrate colonization differences among exclusion cages. All plastics reduced some light (190–700 nm wavelengths) and blocked more ultraviolet light than photosynthetically active radiation. Exclusion cage size did not influence flow boundary layer thickness, but larger exclusions tended to have higher velocity at the substrata surface. Despite light and water velocity differences, algal biomass, macroinvertebrate density, and community composition were similar between exclusion cage types. However, algal assemblages outside exclusion cages differed in composition and had higher biomass compared to inside exclusion cages. In terms of algal and macroinvertebrate colonization, plastic exclusion cage size and material appear to be flexible within the sizes tested, but differences can still exist between exclusion cage communities and those within the stream. Overall, artifacts of screened exclusion cages do not appear to introduce large bias in results of grazer–biofilm studies, but efforts to design exclusion cages that better mimic the natural system should continue.     

Decontamination of a barrier facility using microisolator cages and provisional partitioning

In 2000, the authors found endemic infections of mouse hepatitis virus, minute virus of mice, Syphacia obvelata, and Myobia musculi among mice in a large barrier facility at the University of Mainz. To eliminate the infections, they subdivided the facility into two distinct hygiene units. However, architectural constraints made it impossible to completely separate the HVAC systems of both hygiene units and to establish adequate personnel locks. To compensate for these suboptimal barrier conditions of the two newly established units, the authors replaced the open-top caging and open-servicing system with filter-top cages that were manipulated in cage-changing stations. The authors then depopulated the two units in series, independently eliminating the contaminated mice and restocking the units with SPF animals. In spite of the high infection pressure and the suboptimal barrier conditions, the authors had only a single case of recontamination.     

Medical Applications of Dust-free Rooms. III. Use in an Animal Care Laboratory

Bacterial air sampling in an animal care laboratory showed that dense aerosols are generated during cage changing and cage cleaning. Reyniers and Andersen sampling showed that the airborne bacteria numbered 50 to 200 colony-forming units (CFU)/ft³ of air. Of the viable particles collected by Andersen samplers, 78.5% were larger than 5.5 μm. A low velocity laminar air flow system composed of high-efficiency particulate air (HEPA) filters and a ceiling distribution system maintained the number of airborne viable particles at low levels, generally less than 2 CFU/ft³. Vertical air flow of 15 ft/min significantly reduced the rate of airborne infection by a strain of Proteus mirabilis. Other factors shown to influence airborne infection included type of cage utilized, the use of bedding, the distance between cages, and the number of animals per cage.     

Response,use and habituation to a mouse house in C57BL/6J and BALB/c mice

Animal welfare depends on the possibility to express species-specific behaviours and can be strongly compromised in socially and environmentally deprived conditions. Nesting materials and refuges are very important resources to express these behaviours and should be considered as housing supplementation items. We evaluated the effects of one item of housing supplementation in standard settings in laboratory mice. C57BL/6JOlaHsd (B6) and BALB/cOlaHsd (BALB) young male and female mice, upon arrival, were housed in groups of four in standard laboratory cages and after 10 days of acclimatization, a red transparent plastic triangular-shaped Mouse House™ was introduced into half of the home cages. Animals with or without a mouse house were observed in various contexts for more than one month. Body weight gain and food intake, home cage behaviours, emotionality and response to standard cage changing procedures were evaluated. The presence of a mouse house in the home cage did not interfere with main developmental and behavioural parameters or emotionality of BALB and B6 male and female mice compared with controls. Both strains habituated to the mouse house in about a week, but made use of it differently, with BALB mice using the house more than the B6 strain. Our results suggest that mice habituated to the mouse house rather quickly without disrupting their home cage activities. Scientists can thus be encouraged to use mouse houses, also in view of the implementation of the EU Directive (2010/63/EU).     

Evaluation of a forced-air-ventilated micro-isolation system for protection of mice against Pasteurella pneumotropica.

Studies to date have established that the physical environment inside cages can be controlled adequately by setting the intra-cage ventilation at 60 air changes per hour in a forced-air-ventilated micro-isolation system (FVMIS). In this study, the capability of FVMIS to prevent inter-cage transmission of microorganisms was evaluated using Pasteurella pneumotropica as a reference microorganism. One FVMIS rack and a conventional rack were used, and cages with mice positive for P. pneumotropica and those with P. pneumotropica-free mice were housed on both racks. The mice were examined for P. pneumotropica contamination every 4 weeks after initiating the experiment for 12 weeks using a polymerase chain reaction method. Some P. pneumotropica-free mice housed in open air cages in the conventional rack became positive for P. pneumotropica (four of 28 animals after 4 weeks; eight of 28 animals after 12 weeks), but all P. pneumotropica-free mice housed in the FVMIS cages remained negative for the bacterium throughout the experiment. The results demonstrate that FVMIS can prevent inter-cage transmission of P. pneumotropica when proper cage handling practice is under taken.     

Comparison of behaviour,performance and mortality in restricted and ad libitum-fed growing rabbits

The objective of this study was to determine whether rabbits fed in a restricted regimen (75%) showed increased competition for feeding, drinking and use of specific areas of the cages as compared with those provided feed ad libitum. This evaluation was carried out by measuring their space utilisation in the cage, the incidence of agonistic behaviour and rates of mortality. In total, 504 rabbits between 31 and 66 days of age were used in this study. A total of 200 heavy-weight rabbits and 56 light-weight rabbits were randomly housed in 32 cages, each cage containing eight rabbits: 25 cages housing heavy rabbits and seven cages housing the light-weight ones. They were all fed ad libitum (AD). In addition, a total of 208 heavy-weight rabbits and 40 light-weight rabbits were randomly housed in 31 cages, each of them containing eight rabbits: 26 cages housing heavy weight rabbits and five cages housing light-weight ones. They were all fed a restricted diet (R) regimen. The restriction was calculated to be 75% of the feed consumed by the AD group. The total space available in the cage was 3252 cm², with a stocking density of 24.6 animals/m². Animals between 32 and 60 days of age from 20 different cages were observed nine times per week (morning or afternoon) by means of scan and focal sampling by one observer. During each period, cages were assessed for 5 min, registering every minute the position of all the animals in relation to Area A (feeder), Area B (central part) or Area C (back and drinker area). The incidence of agonistic behaviour such as displacement, biting and jumping on each other was also assessed. Performance variables such as daily gain and feed conversion ratio, in addition to general health status and mortality rates, were recorded for all rabbits. When the rabbits were under restricted feeding, the competition for feed and drink increased with clear signs of agonistic behaviour such as biting, displacement and animals jumping on top of each other. Although this competition was maintained during the entire growing period, the BW homogeneity between animals in the same cage was similar in both cases, suggesting that all animals could consume similar quantities of feed. The possible advantages of a restricted diet, such as better feed conversion ratio, were observed in this study only in the last few weeks of the growing period.