Eugenol as anesthetic for Cnesterodon decemmaculatus (Cyprinodontiformes, Poeciliidae)

Anesthetics are commonly used in fish for surgery and to facilitate capture, handling and transport in aquaculture and experimental procedures. In research, the selection of the anesthetic depends on its properties and on the recovery time. Eugenol has been pointed out as an effective anesthetic for fish, alternative to traditional drugs. Although Cnesterodon decemmaculatus is widely used as a model in ecological bioassays, no anesthetic protocol has been reported for this species. The aim of the present study was to evaluate the induction time (i.e. time to reach anesthetic stage VI) and recovery time in individuals of C. decemmaculatus subjected to eugenol at a fixed concentration, according to sex and pregnancy status. Forty-one fish were divided into three groups: males, pregnant females and non-pregnant females. They were measured for total length, standard length and weight, and the condition factor (K) was calculated. No significant differences in induction and recovery times were found for sex, pregnancy status and K between groups. Results are a contribution toward the development protocol of a standard anesthetic protocol for C. decemmaculatus.

Pain management in zebrafish : Report from a FELASA Working Group

Empirical evidence suggests fishes meet the criteria for experiencing pain beyond a reasonable doubt and zebrafish are being increasingly used in studies of pain and nociception. Zebrafish are adopted across a wide range of experimental fields and their use is growing particularly in biomedical studies. Many laboratory procedures in zebrafish involve tissue damage and this may give rise to pain. Therefore, this FELASA Working Group reviewed the evidence for pain in zebrafish, the indicators used to assess pain and the impact of a range of drugs with pain-relieving properties. We report that there are several behavioural indicators that can be used to determine pain, including reduced activity, space use and distance travelled. Pain-relieving drugs prevent these responses, and we highlight the dose and administration route. To minimise or avoid pain, several refinements are suggested for common laboratory procedures. Finally, practical suggestions are made for the management and alleviation of pain in laboratory zebrafish, including recommendations for analgesia. Pain management is an important refinement in experimental animal use and so our report has the potential to improve zebrafish welfare during and after invasive procedures in laboratories across the globe.

Pathologic copulatory lock in a genetically engineered laboratory mouse breeding pair

A breeding pair of genetically engineered laboratory mice (Mus musculus) presented in apparent copulatory lock (coital tie). After anesthetizing the animals, gentle traction was used to separate the pair at which point a vaginal prolapse was detected and the penis was covered with black, firm, dry crusts and noted to have a solid pale, tan, firm cylindrical mass adhering to its glans. The vaginal prolapse was reduced and the female was returned to its cage. The male mouse had a severely distended bladder which could not be expressed and was euthanized. Histopathologic examination of the distal two-thirds of the penis revealed diffuse, acute coagulative necrosis. The mass adhered to the distal penis was a homogenous granular eosinophilic material consistent with a copulatory plug. While copulatory plugs and locks have been described in some rodent species, they have not been reported in laboratory mice. While the cause of the adherence of the plug to the penis could not be determined, we hypothesize that its adherence to both the penis and the vagina led to the lock and subsequently to ischemic necrosis of the distal penis.

Influence of general anaesthesia on circulating biomarkers of glucose metabolism in pigs

Pigs are widely used in metabolic research with procedures often requiring general anaesthesia. The aim was to investigate the effect of four different anaesthetic protocols: 1) isoflurane inhalation, 2) propofol infusion, 3) a mixture of tiletamine, zolazepam, medetomidine, ketamine and butorphanol (TZMKB)) and 4) ketamine combined with midazolam and xylazine (KMX)) on selected biomarkers during basal and glucose stimulated conditions. Eight domestic pigs were included in a cross-over design. Plasma concentrations of glucose, insulin, C-peptide, glucagon, cortisol, triglycerides, total cholesterol, aspartate amino transferase and alanine amino transferase, creatinine, urea, fructosamine, albumin, free fatty acids (FFAs) and glycerol were measured at baseline, during 2 h of anaesthesia and during 1 h of recovery. Intravenous glucose tolerance test (IVGTT, 0.5 g glucose/kg) was performed after 1 h of anaesthesia. Glucose disappearance rate and areas under the insulin, C-peptide and glucagon curves from the IVGTT were calculated. All four anaesthetic protocols affected glucose metabolism parameters significantly compared with un-anaesthetised pigs, which was particularly evident during IVGTT and for TZMKB and KMX anaesthesia. Propofol additionally influenced the plasma concentrations of triglycerides, FFAs and glycerol significantly. The remaining circulating biomarkers were largely unaffected by anaesthesia. These data underline the importance of considering the anaesthetic protocol in porcine studies of circulating metabolic biomarkers.

Evaluating and developing sealants for the prevention of pulmonary air leakage: A systematic review of animal models

Sealants may provide a solution for pulmonary air leakage (PAL), but their clinical application is debatable. For sealant comparison, standardized animal models are lacking. This systematic review aims to assess methodology and quality of animal models for PAL and sealant evaluation. All animal models investigating lung sealing devices (e.g., staplers, glues, energy devices) to prevent or treat PAL were retrieved systematically from Embase, Pubmed and Web of science. Methodological study characteristics, risk of bias, reporting quality and publication bias were assessed. A total of 71 studies were included (N  =  75 experiments, N  =  1659 animals). Six different species and 18 strains were described; 92% of experiments used healthy animals, disease models were used in only six studies. Lesions to produce PAL were heterogenous, and only 11 studies used a previously reported technique, encompassing N  =  5 unique lesions. Clinically relevant outcomes were used in the minority of studies (imaging 16%, air leak 10.7%, air leak duration 4%). Reporting quality was poor, but revealed an upward trend per decade. Overall, high risk of bias was present, and only 18.7% used a negative control group. All but one study without control groups claimed positive outcomes (95.8%), in contrast to 84.3% using positive or negative control groups, which also concluded equivocal, adverse or inconclusive outcomes. In conclusion, animal studies evaluating sealants for prevention of PAL are heterogenous and of poor reporting quality. Using negative control groups, disease models and quantifiable outcomes seem important to increase validity and relevance. Further research is needed to reach consensus for model development and standardization.

When less is more: Experimental Bishop-Koop technique for reduction in the use of laboratory animals for intestinal pathophysiological studies

The use of animals to gain knowledge and understanding of diseases needs to be reduced and refined. In the field of intestinal research, because of the complexity of the gut immune system, living models testing is mandatory. Based on the 3Rs (replacement, reduction and refinement) principles, we aimed to developed and apply the derived-intestinal surgical procedure described by Bishop and Koop (BK) in rats to refine experimental gastrointestinal procedures and reduce the number of animals used for research employing two models of intestinal inflammation: intestinal ischemia-reperfusion injury and chemical-induced colitis. Our results show the feasibility of the application of the BK technique in rodents, with good success after surgical procedure in both small and large intestine (100% survival, clinical recovery and weight regain). A considerable reduction in the use of the number of rats in both intestinal inflammation models (80% in case of intestinal ischemia-reperfusion damage and 66.6% in chemical-induced colitis in our experimental design) was achieved. Compared with conventional experimental models described by various research groups, we report excellent reproducibility of intestinal damage and functionality, survival rate and clinical status of the animals when BK is applied.

Nomenclature for standardized designation of diploid genotypes in genetically modified laboratory animals

Information about the diploid genotype of a gene-modified or mutant laboratory animal is essential for breeding and experimental planning. It is also required for the exchange of animals between different research groups or for communication with professional genotyping service providers. While there are detailed, standardized rules for creating an allele name of a genome modification or mutation, the notation of the diploid genotype after biopsy and genotyping has not been standardized yet. Therefore, a uniform, generally understandable nomenclature for the diploid genotype of gene-modified laboratory animals is needed. With the here-proposed nomenclature recommendations from the Committee on Genetics and Breeding of Laboratory Animals of the German Society for Laboratory Animal Science (GV-SOLAS), we provide a practical, standardized representation of the genotype of gene-modified animals. It is intended to serve as a compact guide for animal care and scientific personnel in animal research facilities and to simplify data exchange between groups and with external service providers.

Detection of high antibodies titers against rat leukemia virus in an outbreak of reproductive disorders and lymphomas in Wistar rats

Young female Wistar rats from a specific pathogen free breeding colony presented an outbreak of infertility along with neurological symptoms and malignant lymphomas. We evaluated the presence and the potential role of the rat leukemia virus (RaLV) in the disease because these clinical signs could be compatible with a retrovirus. RaLV is a mammalian type C endogenous retrovirus initially isolated from in vitro Sprague-Dawley rat embryo cultures. There are no reports of clinical disease in rats associated with this virus, and little is known about its interaction with the host. Using reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay, we studied the synthesis of the viral particles and the development of an immune response against the virus in this rat colony. The results showed that healthy and diseased Wistar rats synthetized viral RNA but only diseased animals developed a detectable immune response against RaLV envelop protein. Furthermore, rats with lymphomas tended to have higher titers of antibodies against RaLV epitopes than those with infertility or neurological symptoms. The results suggest that increases in the RaLV infectious particle loads could be involved in the development of lymphomas in young rats. The potential causes of RaLV reactivation are discussed.

The use of ball pits and playpens in laboratory Lister Hooded male rats induces ultrasonic vocalisations indicating a more positive affective state and can reduce the welfare impacts of aversive procedures

The advancement and quality of science rely on research that is robust and unbiased in its experimental design, execution, analysis, and reproducibility. In preclinical research, a better understanding of animal emotions and refinement of their husbandry, housing, and handling are important goals in providing good animal welfare in a laboratory setting which underpins rigorous research quality. Induction of positive emotional state in animals is a key component of their well-being, and one approach is to increase their environmental complexity using, for example, ball pits or playpens in rats. In this study, we recorded 50 kHz ultrasonic vocalisations (USVs) during animals’ exposure to the ball pit and playpen. We have previously shown that 50 kHz USVs provide a graded and quantifiable measure of an animal’s emotional state, and here find that access to the ball pit and playpen increases 50 kHz USVs, indicative of a more positive affective state. Using our affective bias test (ABT) we next quantified the animals’ emotional response to an aversive intervention and whether this could be attenuated by access to a playpen. The playpen exposure completely mitigated the negative affective state induced by an anxiogenic drug when compared with animals who experienced the drug in the home cage. Together, these findings suggest ball pits and playpens provide a simple and effective method to improve the welfare of laboratory rats and reduce the cumulative suffering they experience from their housing conditions and minor, aversive procedures.

Ultrasound-guided external jugular and femoral arterial cannulation for juvenile swine

Central venous and arterial access through minimally invasive techniques has been described in adult pigs. This article demonstrates success in juvenile animals. Using ultrasound guidance and the modified Seldinger technique, 5 Fr/15 cm single-lumen central venous catheters and 20 Ga 4.5 cm femoral arterial catheters were placed in six Yorkshire cross-bred swine. All six cases had no loss of venous catheter patency or infection during the 96-hour follow-up period. Arterial catheters remained patent, and no significant bleeding was noted after removal.

Hepatic blood flow in adult Göttingen minipigs and pre-pubertal Danish Landrace x Yorkshire pigs

The liver receives dual blood supply from the hepatic artery and portal vein. The pig is often used as an animal model in positron emission tomography (PET) and pharmacokinetic studies because of the possibility for extensive and direct blood sampling. In this study, we compared measurements of hepatic blood flow in 10 female adult Göttingen minipigs and 10 female pre-pubertal Danish Landrace x Yorkshire (DLY) pigs. Ultrasound transit time flow meter probes were placed around the hepatic artery and portal vein through open surgery, hepatic blood flow measurements were performed, and the liver was weighed. Total hepatic blood flow was on average 363 ± 131 mL blood/min in Göttingen minipigs and 988 ± 180 mL blood/min in DLY pigs (p < 0.001). The mean hepatic blood perfusion was 623 mL blood/min/mL liver tissue and 950 mL blood/min/mL liver tissue (p = 0.005), and the liver weight was 0.58 kg and 1.04 kg, respectively. The mean arterial flow fraction in Göttingen minipigs was 12 ± 7% and lower than in DLY pigs, where it was 24 ± 7% (p = 0.001). Using the gold standard for blood flow measurements, we found that both total hepatic blood flow and blood perfusion were significantly lower in Göttingen minipigs than in DLY pigs. The hepatic blood perfusion and arterial flow fraction in DLY pigs were comparable to normative values from humans. Differences in hepatic blood flow between adult Göttingen minipigs and humans should be considered when performing physiological liver studies in this model.

History of genome editing: From meganucleases to CRISPR

CRISPR-mediated genome editing has undoubtedly revolutionized genetic engineering of animals. With the ability for virtually unlimited modification of almost any genome it is easy to forget which amazing discoveries paved the way for this ground-breaking technology. Here, we summarize the history of genome editing platforms, starting from enhanced integration of foreign DNA by meganuclease-mediated double-strand breaks to CRISPR/Cas9, the leading technology to date, and its re-engineered variants.

Federation of European Laboratory Animal Science Associations recommendations of best practices for the health management of ruminants and pigs used for scientific and educational purposes

Most ruminants and pigs used for scientific and educational aims are bred not for these purposes but in a farm environment. Given the wide range of diseases that these species might have, ensuring that the animals' health status is appropriate can be complex and challenging. The Federation of European Laboratory Animal Science Associations has previously published recommendations for the health monitoring of experimental colonies of pigs (1998) and, respectively, calves, sheep and goats (2000). Unfortunately, the uptake of those recommendations was poor and insufficiently reported in scientific publications. These new recommendations for best practice focus on the main species of ruminants (cattle, sheep and goats) and pigs. They provide general and specific information helpful for designing a health management programme for the suppliers and for the user establishments, as well as guidance on animal procurement. Critical thinking based on the fields of use of the animals is promoted, aiming to help in taking informed decisions rather than establishing an exhaustive exclusion list for pathogens. Implementing the best health and welfare management practices should be done under the guidance of a competent attending veterinarian, with expertise and sufficient authority to take the appropriate action, doubled by excellent communication skills. It is strongly recommended that the user establishment's veterinarian works in close collaboration with the supplier's veterinarian.

Refining the unilateral ureteral obstruction mouse model: No sham, no shame

Fibrosis, as a common final pathway in many renal diseases, contributes significantly to the decline of organ function and to progression to end-stage renal disease. To establish therapeutic interventions that target fibrosis, animal models are essential. The most widely used model of renal fibrosis is the unilateral ureteral obstruction (UUO) model. Typically, the control for this model is a sham-operated animal. Sham surgery causes pain and distress to these control animals, and here we aim to show that there is no difference in the main read-outs of this model between sham-operated animals and non-operated C57BL/6J mice. In five experiments, quantification of Picro Sirius Red stained collagen in the renal cortex did not show any difference between 15 sham and 25 non-operated individuals. A comparison of the regulation of genes involved with fibrosis did not show any difference between sham and non-operated groups at 21 days post surgery either. We conclude that there are no significant differences between non-operated controls and sham animals with respect to collagen deposition and fibrosis pathways in the UUO mouse model.

Bacterial species to be considered in quality assurance of mice and rats

Bacteria are relevant in rodent quality assurance programmes if (a) the animals are at risk and (b) presence in the animals makes a difference for animal research or welfare, for example because the agent regulates clinical disease progression or impacts its host in other ways. Furthermore, zoonoses are relevant. Some bacterial species internationally recommended for the health monitoring of rats and mice, that is, Citrobacter rodentium, Corynebacterium kutscheri, Salmonella spp. and Streptococcus pneumonia, are no longer found in either laboratory or pet shop rats or mice, while there is still a real risk of impact on animal research and welfare from Filobacterium rodentium, Clostridium piliforme, Mycoplasma spp., Helicobacter spp. and Rodentibacter spp., while Streptobacillus moniliformis may be considered a serious zoonotic agent in spite of a very low risk. Modern molecular techniques have revealed that there may, depending on the research type, be equally good reasons for knowing the colony status of some commensal bacteria that are essential for the induction of specific rodent models, such as Alistipes spp., Akkermansia muciniphila, Bifidobacterium spp., Bacteroides fragilis, Bacteroides vulgatus, Faecalibacterium prausnitzii, Prevotella copri and segmented filamentous bacteria. In future, research groups should therefore consider the presence or absence of a short list of defined bacterial species relevant for their models. This list can be tested by cost-effective sequencing or even a simple multiple polymerase chain reaction approach, which is likely to be cost-neutral compared to more traditional screening methods.

Tamoxifen administration in pregnant mice can be deleterious to both mother and embryo

Since it was introduced 20 years ago, tamoxifen-inducible genetic recombination in vivo has become a standard tool in many fields. This technique has great utility, allowing precise temporal and spatial gene recombination mediated by expression of a Cre recombinase-oestrogen receptor hormone binding domain fusion protein. It is frequently used in developmental biology, either for accurate spatio-temporal gene deletion or for lineage-labelling. Administration of high doses of tamoxifen can rapidly induce abortion in pregnant mice but this can be partially overcome by progesterone co-administration. However, administration of tamoxifen to pregnant mice early in pregnancy may have potentially lethal effects on the mother independently of abortion, and can also severely perturb embryonic development. Despite this, only a few published studies mention this fact in passing, and standard parameters for successful or unsuccessful use of tamoxifen in pregnant mice have not been reported. Therefore, in the interests of providing a framework for more humane animal research, we describe our experiences of tamoxifen administration during early gestation in mice. These observations should assist the design of future studies in accordance with the principles of the three Rs (Replacement, Reduction and Refinement of Animals in Research).

Informing efficient pilot development of animal trauma models through quality improvement strategies

Poor quality data in preclinical trials can result from inconsistent and unstandardized experimental processes. Unpredictable pre-intervention variability generates unreliable data, biases outcomes and results in needless waste of animals and resources. We applied Define-Measure-Analyse-Improve-Control (DMAIC) quality improvement processes to pilot development of a swine model of trauma, haemorrhagic shock and coagulopathy. The goal was to reduce variability through protocol standardization and error reduction. Six male Sinclair swine were sequentially anesthetized, intubated, mechanically ventilated and instrumented, then subjected to multiple-hit injury, followed by fluid resuscitation monitoring and coagulation testing. Experimental tasks were defined and mapped. Performance measures were task performance times, subject stabilization time and number of task execution errors. Process improvement was assessed by reduced times and errors, and subject stability at target physiological values. Previously-overlooked performance errors and deficiencies were identified. 'Mistake-proofing' actions included personnel retraining, revisions of standard operating procedures and use of checklists. The quality improvement pilot trial produced a stable model with reduced protocol deviations. Data quality can be improved and animal waste minimized, if experimental planning incorporates strategies to ensure protocol adherence and reduced operator performance variation and errors. Properly designed pilot trials can be essential components of refinement and reduction strategies in animal-based research.

The African spiny mouse ( Acomys spp.) as an emerging model for development and regeneration

The African spiny mouse ( Acomys spp.) is an emerging animal model with remarkable biological characteristics that make it a subject of interest for a broad range of research fields. Typically a desert species adapted to a low-calorie diet, spiny mice develop diabetes-related symptoms when switched to high-energy diets. Spiny mice undergo relatively long gestation periods and have small litters of highly developed pups, making them an adequate model for late organogenesis and perinatal biology. Recently, they have been shown to have remarkable healing and regeneration capabilities, which make them unique among mammals. In this work, we describe our experience in housing a colony of African spiny mice and cover all basic aspects of feeding, maintenance and breeding for research purposes.

Malignant lymphoma with middle ear involvement in a Sprague-Dawley rat

Sprague-Dawley rats are amongst the most widely used animals in biomedical research and malignant lymphoma has long been known to be a frequent neoplasm in these animals. A 9-month-old male control Sprague-Dawley rat from a toxicity study showed gelatinous material in the cranial cavity and dark, thickened cerebral meninges at necropsy. At microscopic evaluation of the temporal bone, neoplastic lymphocytes were seen invading several structures of the middle ear. The neoplastic cells appeared to extend from the marrow of the temporal bone, covered the dorsal part of the tympanic cavity wall, and surrounded and infiltrated the base of the tensor tympani muscle as well as the chorda tympani branch of the facial nerve. The lymphoma was generalized; neoplastic lymphocytes were also noted in numerous other tissues. Literature regarding neoplasms of the middle and inner ear in animals is scarce and, to our knowledge, this is the first report of a lymphoma involving the middle ear of a rat.

Volumetric and linear measurements of lung tumor burden from non-gated micro-CT imaging correlate with histological analysis in a genetically engineered mouse model of non-small cell lung cancer

In vivo micro-computed tomography (CT) imaging allows longitudinal studies of pulmonary neoplasms in genetically engineered mouse models. Respiratory gating increases the accuracy of lung tumor measurements but lengthens anesthesia time in animals that may be at increased risk for complications. We hypothesized that semiautomated, volumetric, and linear tumor measurements performed in micro-CT images from non-gated scans would have correlation with histological findings. Primary lung tumors were induced in eight FVB mice with two transgenes (FVB/N-Tg(tetO-Kras2)12Hev/J; FVB.Cg-Tg(Scgb1a1-rtTA)1Jaw/J). Non-gated micro-CT scans were performed and the lungs were subsequently harvested. In the acquired micro-CT scans, measurements of all identified tumors were determined using the following methods: semiautomated three-dimensional (3D) volume, ellipsoid volume, Response Evaluation Criteria in Solid Tumors (RECIST; sum of largest axial (i.e., transverse) diameter from five tumors), sum of largest axial diameters from all tumors (modified RECIST), and average axial diameter. For histological analysis, all five lung lobes were analyzed and the tumor area was summed from measurements made on five histological sections that were 300 µm apart from each other (covering a total depth of 1200 µm). All micro-CT measurement methods had very strong correlation with histological tumor burden (Pearson's correlation coefficient, 0.87 ( p = 0.0053) -0.98 ( p < 0.0001)). The only methods found to have different correlations were the semiautomated 3D method and the RECIST method (Williams' test for dependent overlapping correlations, p = 0.013). Our results suggest quantification of lung tumor burden from non-gated micro-CT imaging will reflect histological differences between mice and can therefore be used for between-group comparisons or when concerns about systemic health of research animals may limit lengthy anesthetic procedures.

Preputial diverticulum dilation in a Goettingen minipig

Preputial dilation is an infrequently reported condition in pigs. The pathophysiology and etiology is unclear. Causes for diverticulum dilation are proposed to be chronic preputial diverticulitis with subsequent fibrosis of the preputial cavity, phimosis of the preputial orifice or the preputial diverticulum, but the large majority of cases are reportedly idiopathic in nature. Surgical interventions include ablative procedures, but many cases are not treated because of an assumed lack of clinical relevance in pigs not used for breeding. We report a case of progressive preputial dilation that recurred after surgical intervention. Histopathological examination revealed no primary inflammatory condition, contrary to literature suggesting a role for inflammatory mediators in pathogenesis. Phimosis of the preputial orifice was noted post mortem and might be a contributing factor. These findings partially contradict the current assumptions in regards to pathophysiology and treatment choices in the literature and warrant further investigation into alternative therapeutic interventions for this condition.