Multilevel Cages Research Articles

Environmental enrichment promotes adaptive responding during tests of behavioral regulation in male heterogeneous stock rats

Organisms must regulate their behavior flexibly in the face of environmental challenges. Failure can lead to a host of maladaptive behavioral traits associated with a range of neuropsychiatric disorders, including attention deficit hyperactivity disorder, autism, and substance use disorders. This maladaptive dysregulation of behavior is influenced by genetic and environmental factors. For example, environmental enrichment produces beneficial neurobehavioral effects in animal models of such disorders. The present study determined the effects of environmental enrichment on a range of measures related to behavioral regulation using a large cohort of male, outbred heterogeneous stock (HS) rats as subjects. Subjects were reared from late adolescence onwards either in pairs in standard housing with minimal enrichment (n = 200) or in groups of 16 in a highly enriched environment consisting of a large multi-level cage filled with toys, running wheels, and shelters (n = 64). Rats were subjected to a battery of tests, including: (i) locomotor response to novelty, (ii) light reinforcement, (iii) social reinforcement, (iv) reaction time, (v) a patch-depletion foraging test, (vi) Pavlovian conditioned approach, (vii) conditioned reinforcement, and (viii) cocaine conditioned cue preference. Results indicated that rats housed in the enriched environment were able to filter out irrelevant stimuli more effectively and thereby regulate their behavior more efficiently than standard-housing rats. The dramatic impact of environmental enrichment suggests that behavioral studies using standard housing conditions may not generalize to more complex environments that may be more ethologically relevant.

Housing and Environmental Enrichment of the Domestic Ferret: A Multi-Sector Survey.

Simple SummaryHow ferrets across sectors are housed and the environmental enrichment provided (e.g., toys, beds, exploration of new sights and smells) can directly impact their health and wellbeing. Through an online questionnaire reaching ferret caretakers from pet owner, laboratory, zoo, rescue, and working (e.g., pest control) sectors, we describe how ferrets are housed, the enrichment they receive, enrichment types that ferrets most enjoy and those which may be harmful or problematic. Of 754 responses, 82.4% were from pet owners. Most ferrets were housed with at least one other ferret, and the type of housing varied across sectors from single-level cages to free-ranging housing. Environmental enrichments most commonly reported were hammocks, tunnels and human interaction, with ferrets reported to most enjoy digging, tunnels, human interaction and exploration. Scent trails were also reported to be among the most enjoyable enrichments but were rarely provided, suggesting that they could be used more. Problematic enrichment included rubber items, such as Kongs®, which could be chewed and swallowed, narrow tunnels trapping ferrets, and fabrics catching claws. These items should therefore be avoided. Our results suggest that all sectors have room to improve both housing and enrichment to better ferret welfare.Ferrets (Mustela putorius furo) are kept and used in multiple sectors of society, but little is known about how they are housed and what environmental enrichment (EE) they may benefit from. We aimed to help guide caretakers about what housing and EE can be provided for ferrets. Through an online questionnaire of ferret caretakers, including pet, laboratory, zoological collection, rescue and working animal sectors internationally, we described ferret housing, opportunities for exploration, EE provision and caretaker opinions on ferrets’ preferred EE types, and problematic EE. In total, 754 valid responses from 17 countries were analysed, with most (82.4%) coming from pet owners. Most ferrets were housed socially, with housing varying across sectors from single-level cages to free-range housing in a room or outdoor enclosure; pet owners mostly used multi-level cages. The most commonly reported EE included hammocks, tunnels and tactile interaction with caretakers. Respondents reported that ferrets particularly enjoyed digging substrates, tunnels, human interaction and exploration. The most frequently reported problems were that ingestion of unsuitable chew toys and rubber items could cause internal blockages, narrow tunnels could trap ferrets, and certain fabrics that could catch claws. This suggests a need for increased awareness of the risks of these EE types and for more commercially available safety-tested ferret EE. Scent trails were relatively rarely provided but were reported to be enjoyed and harmless, so we recommend that these should be provided more commonly. Our results suggest that there is scope to improve ferret housing and EE provision to benefit ferret welfare across all sectors.

БІОХІМІЧНИЙ ПРОФІЛЬ ТА АКТИВНІСТЬ ЕНЗИМІВ СИРОВАТКИ КРОВІ КУРЕЙ ЗА ЗМІНИ ВИСОТИ РОЗТАШУВАННЯ КЛІТКОВИХ БАТАРЕЙ

In the conditions of industrial poultry farming, the body of hens is constantly exposed to numerous technological stressors, the least studied of which are long-term, which can cause the development of chronic stress. One such technological stressor may be to increase the tier of cage equipment, which is a method of resource conservation in egg poultry and is often used by producers to obtain more eggs from 1 m2 of poultry area. Increasing the level of cage equipment involves the location of the cage in 12 and even 15 tiers, forming 4–5 floors. This allows to increase the concentration of poultry in the poultry house by 4-5 times, compared with 3-tier cage batteries, and 8-10 times – compared to the floor method of keeping. For this livestock in one poultry house can reach 590 thousand hens. However, there are no data on the impact of such a keeping method on the physiological state of hens, and the current rules of VNTP-APK-04.05. for keeping hens in cages designed for 1-3-tier cage batteries. The aim of this work was to study the physiological state of the hen’s body based on the analysis of the biochemical profile and the activity of serum enzymes in their blood depending on the height of the cage batteries. For this purpose, in the conditions of a modern complex for the production of food eggs in one poultry house, 4 groups of hens were formed, each of which was kept on a separate floor-analogue in terms of area and cage equipment. Each floor was equipped with 3-tier cage batteries “Big Dutchman” (Germany), consisting of 1176 cages. It was found that increasing the layering of cage equipment does not have a negative impact on the hen’s body. So, for keeping hens in cages of multilevel cages batteries located on 2-4 floors (4-12 tiers), the biochemical status and activity of their blood serum enzymes were within the physiological norm. In hens kept in cages of the 3rd floor there was an increase, within the physiological norm, aspartate aminotransferase by 7.9%, and in hens of the 2nd floor there was an increase in glucose by 4.6-6.5%, creatinine – by 2.4%, phosphorus by 8.8-9.6%, as well as an increase in the activity of aspartate aminotransferase by 2.2-10.2% and lactate dehydrogenase – by 11.2%. Whereas, when keeping hens in cages of a multi-tiered cage battery on the first floor, there was an increase in glucose levels by 60.5-71.0% (10.9% ˃ of normal), creatinine – by 9.7-12.3% (4.8 % ˃ norm), phosphorus – 82.6–100.0% (23.6% ˃ norm), a decrease in the ratio of calcium and phosphorus by 46.7-50.0% (46.7% ˂ norm), which was confirmed by an increase in alkaline phosphatase activity by 22.3-27.0% (3.4% ˃ normal), as well as an increase in aspartate aminotransferase activity by 3.2-13.8% (1.7% ˃ normal), lactate dehydrogenase – by 48.5-65.1% (10.8% ˃ of normal) and gamma-glutamyltransferase – by 16.4-20.6%. Thus, the main effects of chronic stress caused by keeping hens in the cells of the lower floor of a multi-tiered cage battery are reflected in the biochemical parameters of their serum, namely increased glucose, creatinine, enzyme activity and change of the ratio of calcium and phosphorus.

Does 'playtime' reduce stimulus-seeking and other boredom-like behaviour in laboratory ferrets?

Much environmental enrichment for laboratory animals is intended to enhance animal welfare and normalcy by providing stimulation to reduce 'boredom'. Behavioural manifestations of boredom include restless sensation-seeking behaviours combined with indicators of sub-optimal arousal. Here we explored whether these signs could be reduced by extra daily play opportunity in laboratory ferrets. Specifically, we hypothesised that playtime would reduce restlessness, aggression, sensation-seeking and awake drowsiness, even 24h later in the homecage. Female ferrets (n = 14) were group housed in enriched multi-level cages. Playtime involved exploring a room containing a ball pool, paper bags, balls containing bells, and a familiar interactive human for 1h. This was repeated on three consecutive mornings, and on the fourth morning, homecage behaviour was compared between ferrets who had experienced the playtime treatment versus control cagemates who had not. Their investigation of stimuli (positive = mouse odour or ball; ambiguous = empty bottle or tea-strainer; and negative = peppermint or bitter apple odour) was also recorded. We then swapped treatments, creating a paired experimental design. Ferrets under control conditions lay awake with their eyes open and screeched significantly more, but slept and sat/stood less, than following playtime. They also contacted negative and ambiguous stimuli significantly more under control conditions than they did following playtime; contact with positive stimuli showed no effects. Attempts to blind the observer to treatments were unsuccessful, so replication is required, but the findings suggest that playtime may have reduced both sub-optimal arousal and restless sensation seeking behaviour, consistent with reducing boredom.

Tail Tip Lesions in Mink (Neovison vison): Effects of an Additional Hammock in Multilevel Cages.

Simple SummaryThere are several animal welfare concerns in farmed mink, including the occurrence of wounds, such as tail tip lesions. However, little is known about how these lesions develop. An increasing tendency to develop tail tip wounds was reported by Norwegian mink farmers after the introduction of multilevel cages. It appears that the mink jump directly at a presumably high speed from the upper level towards the nest box on ground level, causing the tail to hit the wire mesh several times. This study investigates whether cage design may be involved in the development of tail tip lesions. Specifically, effects of installing an additional hammock in standard multilevel cages, intended to reduce speed during transitions between cage levels and thereby assumed to lower the incidence and severity of tails hitting the wire mesh, were investigated in 600 mink at three farms (300 with hammocks and 300 without hammocks). More tail tip lesions were found in mink housed in cages without a hammock. Further studies are needed to understand the causal relationship between cage design and tail tip lesions in mink, in order to develop recommendations for improved cage designs and thereby improving animal welfare.The occurrence of wounds in different anatomical regions, such as tail tip lesions, is an important welfare concern in farmed mink. This study investigated whether mechanical factors attributed to cage design in multilevel cages may be involved in the etiology of tail tip lesions. Specifically, effects of an additional hammock intended to reduce speed during transitions between cage levels and thereby assumed to lower the incidence and severity of tails hitting the wire mesh were investigated. Three mink farms and a total of 600 mink participated in the study. On each farm, brown female mink (n = 100) were either housed in multilevel cages equipped with plastic hammocks (placed either perpendicular or parallel to the sidewalls) or in standard multilevel cages without hammocks (n = 100). The study was conducted from December to March using singly housed females. Significant differences in the number of tail tip wounds were found between groups with a hammock installed in the cage vs. control groups in two of the farms (p = 0.029 and p = 0.031), with more wounds developing in cages without a hammock. Furthermore, there was a trend towards difference in the number of tail tip wounds in groups with hammocks installed perpendicular vs. groups with hammocks installed parallel to the cage sidewalls, but a potential farm effect cannot be ruled out. This study is the first to suggest that mechanical factors associated with cage design may play a role in the etiology of tail tip lesions in farmed mink. Further studies are needed to understand the causal relationship between cage design and tail tip lesions in mink.

The Stand-Alone Cervical Cages with Integrated Screw Fixation: Results in 315 Consecutive Operated Levels

Introduction Background: Cervical disc disease at C2/3, C3/4 and C7/T1 is less common. Fusion with cages & plating is the standard treatment at these levels and in multi-level disc disease. This is not without significant risks related to the need of larger exposure and anterior muscular dissection. Stand-alone cages with integrated screw fixation obviate the need for plating and larger exposure. Material and Methods To assess the exposure / cage related morbidities and fusion rates in Stand-Alone cervical cages with Integrated Screw Fixation. Design: Retrospective chart review. Subjects: 315 levels were operated in 253 patients from February 2009 to February 2015. Single and Multilevel cages were performed in 201 and 52 patients respectively. 201 of the 253 patients underwent single level discectomy with Stand-Alone cervical cages with Integrated Screw Fixation at C3/4 and C7/T1 levels. 52 patients underwent 114 multi-level discectomies with Stand-Alone cervical cages with Integrated Screw Fixation Results Operative time was shorter. There was no reported permanent exposure/ cage related morbidities in all operated levels. 3 patients with traumatic disc disruption required further surgery for lateral mass fixation. 12 patients had mild dysphagia that resolved during follow up with no patient having complains of dysphagia at 3- months follow up. Fusion rates were 95% at single level and 90% at multi-level discectomies at the last follow up. No patient required cage related surgical revision. Conclusion The current results support the use of Stand-Alone cervical cages with Integrated Screw Fixation especially at difficult levels at C3/4 and C7/T1 and in multi-level discectomies as it obviate the need for plating and larger exposure with less reported dysphagia and implant related complications.

Environmental enrichment rescues the effects of early life inflammation on markers of synaptic transmission and plasticity

Environmental enrichment (EE) has been successful at rescuing the brain from a variety of early-life psychogenic stressors. However, its ability to reverse the behavioral and neural alterations induced by a prenatal maternal infection model of schizophrenia is less clear. Moreover, the specific interactions between the components (i.e. social enhancement, novelty, physical activity) of EE that lead to its success as a supportive intervention have not been adequately identified. In the current study, standard housed female Sprague-Dawley rats were administered either the inflammatory endotoxin lipopolysaccharide (LPS; 100μg/kg) or pyrogen-free saline (equivolume) on gestational day 15. On postnatal day 50, offspring were randomized into one of three conditions: EE (group housed in a large multi-level cage with novel toys, tubes and ramps), Colony Nesting (CN; socially-housed in a larger style cage), or Standard Care (SC; pair-housed in standard cages). Six weeks later we scored social engagement and performance in the object-in-place task. Afterwards hippocampus and prefrontal cortex (n=7–9) were collected and evaluated for excitatory amino acid transporter (EAAT) 1-3, brain-derived neurotrophic factor (BDNF), and neurotrophic tyrosine kinase, receptor type 2 (TrkB) gene expression (normalized to GAPDH) using qPCR methods. Overall, we show that gestational inflammation downregulates genes critical to synaptic transmission and plasticity, which may underlie the pathogenesis of neurodevelopmental disorders such as schizophrenia and autism. Additionally, we observed disruptions in both social engagement and spatial discrimination. Importantly, behavioral and neurophysiological effects were rescued in an experience dependent manner. Given the evidence that schizophrenia and autism may be associated with infection during pregnancy, these data have compelling implications for the prevention and reversibility of the consequences that follow immune activation in early in life.

Physiological and pharmacokinetic effects of multilevel caging on Sprague Dawley rats under ketamine-xylazine anesthesia.

While the cage refinement is a necessary step towards improving the welfare of research rats, increasing the complexity and surface area of the living space of an animal may have physiological impacts that need to be taken into consideration. In this study, ketamine (80 mg/kg) and xylazine (10 mg/kg) caused a short duration anesthesia that was significantly decreased in Sprague-Dawley rats housed in multilevel cages (MLC), compared to rats housed in standard cages (SDC). The withdrawal reflex, the palpebral reflexes and the time-to-sternal all occurred earlier in MLC housed rats, suggesting an effect of housing on the physiology of the rats. In addition, during anesthesia, cardiac frequencies were increased in animals housed in the smaller SDC. Respiratory frequencies, the blood oxygen saturation and rectal temperatures during anesthesia did not vary between conditions during the anesthesia. While xylazine pharmacokinetics were unchanged with caging conditions, the clearance and half-lives of ketamine and its metabolite, norketamine, were altered in the rats housed in MLC. Finally, while no difference was ultimately seen in rat body weights, isolated liver and adrenal gland weights were significantly lighter in rats housed in the MLC. Increasing cage sizes, while having a positive impact on wellbeing in rats, can alter anesthetic drug metabolism and thus modify anesthesia parameters and associated physiological processes.

Effect of multilevel laboratory rat caging system on the well-being of the singly-housed Sprague Dawley rat.

Current regulations emphasize that good husbandry practices allow animals to engage in species appropriate postural adjustments without touching the enclosure walls. This study evaluated the well-being of rats housed in a commercially available multilevel rat caging system, with or without access to the upper level of the caging. The evaluation methodologies included assessment of behavioral observations in the home cage, physiological assessment of metabolism and immune function, and determination of the affective state using a spatial cognitive bias assay. The study determined that rats that were provided access to the full multilevel cage during testing after initial restriction to the lower level of the cage demonstrated behavioral changes consistent with a positive affective state, while those with no changes to their housing situation had no significant differences in their affective states. Rats that were consistently housed with access restricted to the lower level of the cage exhibited a tendency to increased neutrophil:lymphocyte ratios as compared with those provided with access to all levels of the multilevel cage. There were no differences in body weight demonstrated between the experimental groups. Overall use of the cage space, as documented through analysis of behavioral observations in the home cage, demonstrated no significant differences in preferred location in the cage during the light or dark cycles, though rats with access to both levels of the cage were significantly more active during the light cycle. The results of this study suggest that the use of a multilevel caging system may improve the well-being of rats used in research.

Environmental enrichment mitigates the sex-specific effects of gestational inflammation on social engagement and the hypothalamic pituitary adrenal axis-feedback system.

Modest environmental enrichment (EE) is well recognized to protect and rescue the brain from the consequences of a variety of insults. Although animal models of maternal immune activation (MIA) are associated with several neurodevelopmental impairments in both the behavioral and cognitive functioning of offspring, the impact of EE in protecting or reversing these effects has not been fully evaluated. In the present study, female Sprague-Dawley rats were randomized into EE (pair-housed in a large multi-level cage with toys, tubes and ramps) or animal care control (ACC; pair-housed in standard cages) conditions. Each pair was bred, following assignment to their housing condition, and administered 100μg/kg of lipopolysaccharide (LPS) on gestational day 11. After birth, and until the end of the study, offspring were maintained in their respective housing conditions. EE protected against both the social and hypothalamic pituitary adrenal axis consequences of MIA in juvenile male rats, but surprisingly not against the spatial discrimination deficits or accompanying decrease in glutamate levels within the hippocampus (as measured via LCMS-MS). Based on these preliminary results, the mechanisms that underlie the sex-specific consequences that follow MIA appear to be dependent on environmental context. Together, this work highlights the importance of environmental complexity in the prevention of neurodevelopmental deficits following MIA.

Chinchilla husbandry: an overview of correct care

Chinchillas are increasingly being kept as pets in the UK and are occasionally being seen in veterinary practices. They are small, long-lived rodents that are generally most active during the night. They have soft dense fur which may become detached if handled roughly. They are social animals and benefit from being kept in pairs or small groups. Chinchillas require large multi-level cages as they are active animals and like to jump. Diet should consist of hay, chinchilla nuggets and occasional high fibre treats. Many of the conditions encountered in veterinary practice are as a result of inadequate husbandry or diet; dental disease, digestive disorders, diabetes mellitus and heatstroke may all be seen. Their active nature means chinchillas are also prone to traumatic injury. Veterinary nurses can play an important role in educating owners (and prospective owners) about the needs of their pets.

Bioabsorbable anterior lumbar plate fixation in conjunction with cage-assisted anterior interbody fusion.

An in vitro biomechanical study was conducted to determine the effects of anterior stabilization on cage-assisted lumbar interbody fusion biomechanics in a multilevel human cadaveric lumbar spine model. Three spine conditions were compared: harvested, bilateral multilevel cages (CAGES), and CAGES with bioabsorbable anterior plates (CBAP), tested under flexion-extension, lateral bending, and axial rotation. Measurements included vertebral motion, applied load, and bending/rotational moments. Application of anterior fixation decreased local motion and increased stiffness of the instrumented levels. Clinically, this spinal stability may serve to promote fusion. Coupled with the bioabsorbability of the plating material, the bioabsorbable anterior lumbar plating system is considered biomechanically advantageous.

Multilevel anterior lumbar interbody cages: an in vitro biomechanical assessment

Darrel S. Brodke, MD, R. Alexander Mohr, BS, Salt Lake City, UT, USA; Jeffrey C. Wang, MD, Los Angeles, CA, USA; Jim A. Youssef, MD, Durango, CO, USA; Bao-Khang N. Nguyen, BS, Kent N. Bachus, PhD, Salt Lake City, UT, USAIntroduction: Threaded titanium interbody cages have become widely popular for use in lumbar fusion surgery. They are commonly used as stand-alone devices for single-level fusions, occasionally for two-level fusions and rarely to fuse three or more levels. Despite initial enthusiasm about multilevel cage constructs, there has been an increase in reported pseudarthrosis rates and concern for stability. The published mechanical information on single-level cages cannot be directly applied to the multilevel construct. To date, no biomechanical studies have evaluated the stability of multilevel fusion constructs.Purpose: This study was designed to assess the stiffness of multilevel cage constructs in flexion-extension, lateral bending and axial torsion. A comparison is made between one-, two- and three-level stand-alone cage constructs, and each was compared with the intact spine and posterior pedicle screw instrumentation. Finally, a comparison was made between the three-level anterior cage construct, posterior pedicle screw instrumentation and combined anterior-posterior instrumentation. A better understanding of construct biomechanics will guide clinical decision making.Materials and methods: Twelve calf spines (L1–6) were used for this study. Each was tested on a custom pneumatic four-axis spine simulator. Moments of 5 Nm were applied in flexion-extension, lateral bending and torsion sequentially, while a 50-N axial compressive preload was maintained. In attempt to apply pure moments, one moment was independently applied while the remaining two were actively maintained at zero. After testing of the intact specimen, six of the spines were prepared with sequential cage constructs (single-level L3–4, two-level L3–5 and three-level L2–5), using BAK/L cages (Sulzer SpineTech, MN). Posterior instrumentation was then added at L2–5. Data were compared with six specimens that underwent posterior pedicle screw instrumentation, using Silhouette System (Sulzer SpineTech, MN). Statistical analysis was performed using analysis of variance and Fisher's post hoc test.Results: In the single-level cage construct, L3–4, stiffness was significantly increased in lateral bending 6 times over the intact spine, from 1.4 to 8.7 Nm (p<.01). Flexion-extension and torsional stiffness were increased 82% (7.9 to 14.4 Nm) and 47% (7.3 to 10.7 Nm), respectively, although these were not statistically significant. Single-level posterior pedicle screw instrumentation was stiffer than the anterior cage construct in flexion-extension (36.3 Nm) and lateral bending (25.7 Nm), similar in torsion (11.8 Nm), and significantly increased over the intact specimen in all three planes (p<.01).In the two-level cage construct, L3–4 and L4–5, lateral bending stiffness was again significantly increased over the intact specimen, from 0.9 to 4.1 Nm (p<.005). Neither the flexion-extension nor torsional stiffness of the cage construct were significantly different than the intact specimen. Posterior pedicle screw instrumentation significantly increased stiffness 4 times over the anterior cages in flexion-extension (14.4 to 39.5 Nm) and 8 times in lateral bending (4.1 to 31.9 Nm) (p<.001).The three-level cage construct, L2–3, L3–4 and L4–5, showed no significant differences from the intact specimen in flexion-extension, lateral bending or torsion. Posterior pedicle screw instrumentation was dramatically stiffer in all motion segments, as compared with both the intact spine and the anterior cage construct (p<.0001). Both flexion-extension and lateral bending stiffness were 8 times greater with the posterior instrumentation than the cages alone. However, when posterior nonsegmental pedicle screw instrumentation was added to the cage construct, the stiffness significantly increased (p<.0001).Conclusion: Multilevel anterior stand-alone cage constructs show progressively decreasing stiffness in all planes, flexion-extension, lateral bending and torsion, as fusion levels are added. Whereas the single-level cage construct is stiffer than the intact spine, comparable to posterior pedicle screw instrumentation, and clinically successful, the multilevel constructs are not. Two-level constructs are questionably able to maintain adequate stiffness. Three-level stand-alone cage constructs are no stiffer than the intact mobile spine. The addition of posterior pedicle screw instrumentation to the three-level anterior cage construct significantly increases stiffness in all planes. If a three-level interbody fusion is contemplated, this study supports the addition of posterior instrumentation.

Care Guide Gives Labs More Freedom

Boston—The Bible of lab animal care—the Guide for the Care and Use of Laboratory Animals —came out with a new scriptural interpretation last week, unveiled at a conference in Boston. The revision, the first to the powerful guide since 1985, allows researchers to alter old standards for space allotments and cage construction to focus instead on enhancing animals' sense of “wel-being”—for example, housing playful animals such as cats and chimpanzees in multilevel cages with plenty to distract them. Researchers welcomed the changes, but many in the animal-welfare movement object, saying the new guidelines are subjective and difficult to enforce.

Care Guide Gives Labs More Freedom

Boston—The Bible of lab animal care—the Guide for the Care and Use of Laboratory Animals—came out with a new scriptural interpretation last week, unveiled at a conference in Boston. The revision, the first to the powerful guide since 1985, allows researchers to alter old standards for space allotments and cage construction to focus instead on enhancing animals' sense of “wel-being”—for example, housing playful animals such as cats and chimpanzees in multilevel cages with plenty to distract them. Researchers welcomed the changes, but many in the animal-welfare movement object, saying the new guidelines are subjective and difficult to enforce.