Showing papers in "Lab Animal in 2009"

Correlation between body weight changes and postoperative pain in rats treated with meloxicam or buprenorphine.

Abstract: It is essential to identify objective and efficient methods of evaluating postoperative pain in rodents. The authors investigated whether postoperative changes in rates of body weight gain could serve as a measure of the efficacy of meloxicam or buprenorphine analgesia in growing rats. Young adult male Lewis rats underwent general endotracheal anesthesia and thoracotomy and were treated postoperatively for 3 d with saline (no analgesia), buprenorphine (six doses of 0.1 mg per kg) or meloxicam (three doses of 1 mg per kg). The authors evaluated rats' daily growth rates for 5 d after surgery and compared them with baseline (preoperative) growth rates. To discriminate between the effects of postoperative pain and other concurrent physiologic effects associated with anesthesia, thoracotomy or analgesia, the authors evaluated weight changes in multiple control groups. Treatment with buprenorphine in the absence of any other procedure or with anesthesia alone significantly affected rats' body weight. Notably, growth rate was maintained at near normal levels in rats treated postoperatively with meloxicam. These findings suggest that growth rate might serve as an efficient index of postoperative pain after major surgical procedures in young adult rats treated with meloxicam but not in rats treated with buprenorphine.

A serological survey to evaluate contemporary prevalence of viral agents and Mycoplasma pulmonis in laboratory mice and rats in western Europe

Abstract: To evaluate current prevalence rates of 24 viruses and of the bacterium Mycoplasma pulmonis, the authors retrospectively surveyed serological data obtained from laboratory mice and rats housed in more than 100 western European institutions. Serum samples were submitted to the authors' institution for testing between January 2007 and June 2008. The prevalence of an infection was defined as the percentage of tested samples that yielded positive results for a specific agent. In mice, the most commonly detected infectious agents were murine norovirus (prevalence of 31.8%), mouse hepatitis virus (5.5%), mouse rotavirus (1.7%) and parvoviruses (1.0%). In rats, parvoviruses (12.1%) and M. pulmonis (3.6%) were the most prevalent infectious agents. Most rodent parvovirus infections could be attributed to mouse parvovirus in mice and to rat minute virus or to Kilham rat virus in rats. These data suggest the importance of up-to-date animal health monitoring programs and should stimulate the scientific community to further improve the microbiological quality of laboratory rodents.

Analysis of environmental sound levels in modern rodent housing rooms

Abstract: Noise in animal housing facilities is an environmental variable that can affect hearing, behavior and physiology in mice. The authors measured sound levels in two rodent housing rooms (room 1 and room 2) during several 24-h periods. Room 1, which was subject to heavy personnel traffic, contained ventilated racks and static cages that housed large numbers of mice. Room 2 was accessed by only a few staff members, contained static cages only and housed fewer mice. In both rooms, background sound levels were usually about 80 dB, and transient noises caused sound levels to temporarily rise 30-40 dB above the baseline level; such peaks occurred frequently during work hours (8:30 AM to 4:30 PM) and infrequently during non-work hours. Noise peaks during work hours in room 1 occurred about two times as often as in room 2 (P = 0.01). Use of changing stations located in the rooms caused background noise to increase by about 10 dB. Loud noise and noise variability were attributed mainly to personnel activity. Attempts to reduce noise should concentrate on controlling sounds produced by in-room activities and experimenter traffic; this may reduce the variability of research outcomes and improve animal welfare.

A method for gender determination in newborn dark pigmented mice.

Abstract: In many studies using mice, investigators must determine pups' gender at a very early postnatal stage. The gender of mouse pups is typically assessed by measuring the anogenital distance, which is greater in males than in females. This method, however, has proven to be difficult and not completely reliable. The authors describe a quick, easy and reliable method to establish the gender of pigmented mice. In male mice, a pigment spot on the scrotum is visible to the naked eye from the first day of life onwards, whereas female pups lack visible pigmentation in the anogenital region. In lightly pigmented or albino mice, the pigmentation is not obvious or not at all visible. The authors show that identifying this pigment spot is a more accurate and efficient method of determining pup gender compared with measurement of the anogenital distance. This 'spot on' method would therefore be a useful adjunct to conventional methods for determining the gender of pigmented neonatal mice.

Effects of cage size and enrichment on reproductive performance and behavior in C57BL/6Tac mice.

Abstract: The authors examined the effects of cage size and enrichment on mouse breeding performance and behavior. Breeding trios of C57BL/6Tac mice were housed in cages of two different sizes ('standard' and 'large' cages with 82 in(2) and 124 in(2) floor space, respectively). Half of the cages of each size contained four enrichment items (Nestlet, plastic tunnel, nylon rings and running wheel), whereas the remaining cages had no enrichment. The authors measured the following reproductive parameters: litter size, number of pups that survived to weaning age, average pup weights at 21 d after birth and number of days between births of litters. A subset of weaned male and female pups from each cage size and enrichment condition completed a suite of behavioral tests. Pups raised in large cages weighed less than those raised in standard cages. Enrichment and cage size had certain behavioral effects, which were dependent on gender and behavioral measure. Male pups born in enriched cages showed more anxiety-like behavior and less exploration than did males born in non-enriched cages. Though being raised in enriched or large cages did not clearly improve pups' performance in behavioral tests, enrichment (regardless of cage size) did significantly benefit reproductive performance; pups from non-enriched cages weighed less than pups from enriched cages, and fewer survived to weaning age.

Shoaling preferences and the effects of sex ratio on spawning and aggression in small laboratory populations of zebrafish (Danio rerio)

Abstract: Owing to a lack of basic information on the biology of zebrafish (Danio rerio), lab managers must often base decisions regarding the care and use of this species on anecdotal information. In an effort to provide researchers with context-specific behavioral information, the authors evaluated shoaling and spawning behaviors in small groups of zebrafish. In each shoaling assay, a fish was given a choice to shoal with either a single fish or a group of three fish. Females preferred to shoal with a group of three individuals rather than with a single individual, regardless of the sex of the other fish. Males preferred groups of three males over single males but preferred single females to groups of three females. In spawning assays, zebrafish were placed in breeding tanks in one of three sex ratios (1 male:1 female; 3 males:1 female; 1 male:3 females). Reproductive efficiency did not differ among groups, but aggression (evaluated according to presence of shed scales) was more frequently observed in the male-dominated treatment group.

Insights into modeling streptozotocin-induced diabetes in ICR mice.

Abstract: Streptozotocin (STZ)-induced diabetes in ICR mice is often used to model diabetes mellitus and its complications, as well as other pathologies. In studies of diabetes progression and effects of newly developed treatments, experimental results may be difficult to interpret because blood glucose levels (BGLs) of untreated diabetic control animals tend to decline substantially during typical experimental time spans of 8-11 h. To address this problem, the authors examined several experimental conditions that might affect BGL stability, including STZ dose, initial mouse weight, fasting regimen and light:dark cycle. The authors found that diabetes severity was dependent on initial mouse weight and that weight loss after diabetes induction was less severe in heavier mice. Furthermore, a dose of 150 mg STZ per kg body weight was sufficient to induce stabilized acute diabetes without causing many complications. Finally, BGL could be stabilized in diabetic mice that were not treated with insulin by avoiding pre-fasting before an 8-h experiment and by allowing mice limited access to food during the experiment.

Refining timed pregnancies in two strains of genetically engineered mice.

Abstract: In order to efficiently generate genetically engineered mouse (GEM) fetuses or neonates of a specified age range, researchers must develop strain-specific strategies, including reliable early pregnancy detection. The authors evaluated pregnancy indices (pregnancy rate, plug rate, pregnant plugged rate, first litter size and body weight) in two GEM breeding colonies: homozygous soluble epoxide hydrolase knockout (sEHKO) mice (n = 164 females) and L7-tau-green fluorescent protein (GFP) transgenic mice (n = 61 females). The goals of the study were to determine the most accurate early pregnancy indicator and to reliably and cost-effectively produce timed pregnant females that were between gestation days 16 and 18. The authors set up each timed mating by placing two naturally synchronized females with a male for 48 h. When males were present, personnel checked each female daily for a vaginal plug. They then weighed the females immediately, 1 week and 2 weeks after removing the males. In both sEHKO and GFP colonies, increases in body weight at 1 and 2 weeks after timed male exposure more reliably and consistently indicated pregnancy than did plug detection. Further evaluations and protocol refinements are planned based on litter size and litter number in these colonies.

Ammonia and carbon dioxide concentrations in disposable and reusable static mouse cages.

Abstract: The value of a static mouse cage is partially determined by the cage's ability to dissipate carbon dioxide and ammonia. The authors compared the concentrations of ammonia and carbon dioxide produced by mice housed in two types of static isolator cages: a newly introduced disposable cage and a conventional reusable cage. Female mice were housed in three disposable and three reusable cages (n = 5 per cage). After 7 d, groups that were housed in disposable cages were rehoused in fresh reusable cages and vice versa. Intracage carbon dioxide, ammonia, temperature and relative humidity were measured daily. Overall, there were no significant differences in carbon dioxide or ammonia concentrations between the cage types. Within 30 min of placing mice in cages, carbon dioxide concentrations rose to more than 10,000 ppm in both cage types and rarely dropped below 8,000 ppm during both phases of the study. Ammonia concentrations rose slowly until day 4 and then began to rise rapidly. The maximum average ammonia concentration was 710 ppm. There was a highly significant relationship between increasing levels of humidity and ammonia production in the disposable cages (r = 0.88). For the reusable cages, the correlation was not as strong (r = 0.68). Both cage types were similar in their ability to dissipate carbon dioxide and ammonia. The suggested frequency of cage changing can only be estimated; on the basis of existing literature, it seems prudent to change cages when the ammonia concentration reaches 50 ppm.

Age dependence of glucose tolerance in adult KK-Ay mice, a model of non-insulin dependent diabetes mellitus.

Abstract: Yellow KK mice carrying the 'yellow obese' gene Ay are a well established polygenic model for human non-insulin dependent diabetes mellitus. These animals develop marked adiposity and decreased glucose tolerance relative to their control littermates, KK mice. The authors monitored glucose tolerance in KK-Ay mice over time and observed a significant (P

The susceptibility of three strains of Chinese minipigs to diet-induced type 2 diabetes mellitus.

Abstract: Researchers have extensively used animal models to study diabetes mellitus. In this study, the authors determined the susceptibility of three strains of Chinese minipigs to diet-induced type 2 diabetes mellitus. For 8 months, the researchers fed Nongda control minipigs (n = 4) a normal diet and fed Bama, Wuzhishan and Nongda minipigs (n = 6 per group) a high-sucrose, high-fat diet. They measured the minipigs' body weights, fasting serum glucose concentrations and insulin concentrations each month. Every 2 months, they measured serum triglyceride, cholesterol, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels and carried out intravenous glucose tolerance tests (IVGTTs). The Bama and Wuzhishan minipigs were relatively susceptible to diabetes induced by the high-sucrose, high-fat diet, though susceptibility differed among individual animals in the same strain. On the other hand, Nongda minipigs were relatively resistant to diet-induced diabetes. These results provide a foundation for diabetes-related genetic analyses in minipigs with high and low susceptibility to diet-induced type 2 diabetes.

A critical appraisal of open- and closed-chest models of experimental myocardial ischemia.

Abstract: Myocardial ischemia is one of the most extensively studied topics in modern cardiovascular research. Early investigators first reported experimental myocardial ischemia (EMI) in 1862. The open-chest (surgical) approach is a well-developed model of EMI that enables researchers to directly access and observe the heart. With this approach, EMI is generally induced by surgical ligation of a coronary artery. A drawback of the open-chest model is the need for major surgery, which can result in local and systemic side effects. Alternative closed-chest models of EMI have been developed; most of these models involve endovascular catheterization with coronary artery embolization or thrombosis. Closed-chest techniques eliminate the need for invasive surgery, and the resultant model is more physiologically similar to clinical myocardial ischemia than is EMI produced by artery ligation. The authors present a review of open- and closed-chest models of EMI and discuss the advantages and disadvantages of each approach.

Management of aquatic turtle shell fractures.

Abstract: In a previous column, the author discussed the overall management of turtle shell injuries. This column continues by describing basic techniques for repairing and stabilizing fractured turtle shells.

Efficiency and safety of a technique for drawing blood from the hamster cranial vena cava.

Abstract: The authors evaluated the efficiency and safety of a technique for drawing blood from the cranial vena cava of the hamster (Mesocricetus auratus). They collected blood from Golden Syrian hamsters (n = 15) and from epileptic hamsters (GASH/Sal strain; n = 10) that were anesthetized with isoflurane. Four epileptic hamsters constituted a control group that underwent anesthesia but not blood collection. For blood sampling, a needle connected to a syringe was inserted at a site between 0.2 and 0.6 cm from the manubrium; the depth of insertion was 0.3-1.0 cm. Blood collection was successful in all hamsters except one, and the volume of collected blood ranged from 0.2 ml to 1.5 ml. All hamsters recovered quickly from the procedure, and none showed obvious signs of pain or stress. At necropsy (24 h after the procedure), six subjects showed small local hematomas, and eight showed vascular lacerations of limited severity. Lungs and hearts did not show any damage related to vein puncture. This relatively simple blood collection technique seems to be efficient and safe in hamsters.

Simulating the fine-branch arboreal niche and exercising mice to elicit above-branch quadrupedal grasping and climbing.

Abstract: The fine-branch niche is a natural setting found among the slender vines and terminal branches of shrubs and tree canopies. In this study, the authors designed two simulations of this setting for laboratory mice. Their main goal was to model phenotypic plasticity in a small, clawed mammal, in order to better understand the effect of a thin-branch arboreal setting on musculoskeletal growth and behavior of these animals. The authors exposed mice to the smaller climbing setting for limited amounts of time (e.g., 30 min) and used the larger setting to permanently house another group of mice. Mice in both the limited and continuous climbing groups succeeded at quadrupedal climbing among a complex of thin branch segments. This led the authors to postulate that similarly sized pre-primates that lacked the unique features of today's primates could potentially have exploited this niche. The mice housed in the continuous model remained healthy and showed no signs of aggression, leading the authors to suggest that animal care personnel could use similar models as forms of enrichment for laboratory mice.

Management of freshwater turtle shell injuries.

Abstract: Repair of injured turtle shells can be difficult and time-consuming. This article describes how to manage the freshwater turtle in this phase of healing and how to keep fracture sites 'water-free'.

Regulatory issues regarding the use of food and water restriction in laboratory animals.

Abstract: While investigating certain aspects of animal physiology, neurology or behavior, research scientists sometimes must limit the amount of food or water provided to animals used in a study. Such limitations can negatively impact the health and welfare of laboratory animals by, for example, causing them to experience distress or pain. The author discusses the veterinary and regulatory concerns that laboratory personnel should consider when limiting food or water given to research animals. He concludes that by adequately addressing the needs of animals receiving less food or water than required by regulation, researchers will improve both animal care and scientific study results.

The human-animal bond with laboratory animals.

Abstract: In the author's experience, a bond--whether intentional or not--is often established between humans and animal research subjects. Behavioral theorists suggest that human-animal relationships can take several different forms. The author discusses several occasions in which she perceived one type of relationship with a research animal and was later surprised when the animal's behavior suggested that the bond was actually of a different nature. In the author's opinion, laboratory staff should be aware of the potential of bonding and should work to ensure that the desired human-animal relationships are developed. This may enhance the well-being of animals and staff and improve research efficacy.

Novel food items as environmental enrichment for rodents and rabbits.

Abstract: This column discusses the use of novel dietary supplements as environmental enrichment for rodents and rabbits. The purpose of enrichment is to encourage behaviors that are appropriate for a particular species and that satisfy an animal's physical and psychological needs.

Comparison of ketamine-pentobarbital anesthesia and fentanyl-pentobarbital anesthesia for open-heart surgery in minipigs

Abstract: The authors analyzed and compared the cardiovascular effects of two anesthetic combinations in minipigs undergoing open-heart surgery and cardiopulmonary bypass. Pigs in group K (n = 15) were anesthetized with low-dose ketamine combined with pentobarbital (5 mg per kg and 20 mg per kg, respectively, for induction; continuous intravenous infusion of 5 mg per kg per h and 10 mg per kg per h, respectively, for maintenance). Pigs in group F (n = 15) were treated with fentanyl and pentobarbital (20 μg per kg and 20 mg per kg, respectively, for induction; continuous intravenous infusion of 20 μg per kg per h and 10 mg per kg per h, respectively, for maintenance). Most pigs remained stable during the surgical procedures and survived for at least one day after surgery; two pigs in group F died during or soon after surgery. Heart rate and mean arterial pressure after bypass were significantly lower in group F than in group K, and pigs in group F required higher doses of inotropic agents to maintain cardiac function. Results suggest that for open-heart surgery and bypass in minipigs, ketamine-pentobarbital anesthesia is associated with more stable cardiovascular conditions than is fentanyl-pentobarbital anesthesia.

The cost of animal research.

Abstract: The US biomedical research community has long debated how to bill different types of animal research costs. Specifically, which aspects of animal research should be charged as direct costs, and which should be charged as indirect (or facilities and administrative) costs? In this paper, the author describes why the community has yet to clearly define what constitutes indirect costs. He then suggests how researchers, administrators and government officials can categorize different aspects of animal research as direct or indirect costs.

A simple method for assessing analgesic requirements and efficacy in rodents.

Abstract: Evaluation of pain in the clinical setting is an ongoing challenge for veterinarians, researchers and IACUCs. Behavioral assessment, a common technique for evaluating pain, is subjective and difficult to translate into quantifiable data. The authors propose measuring changes in body weight, food consumption and water consumption as a simple and objective method for evaluating postsurgical pain and analgesic efficacy in rodents.

Efficacy of auditory enrichment in a prosimian primate (Otolemur garnettii).

Abstract: Research suggests that auditory environmental enrichment might reduce abnormal behavior in certain primate species. The authors evaluated the behavioral effects of exposure to music in a prosimian primate (Garnett's bushbaby; Otolemur garnettii). They exposed bushbabies to a Mozart concerto for 15 min per day for 20 d (5 h exposure total), video-recorded them and subsequently analyzed the frequency of subjects' grooming and stereotypic behaviors. The authors compared the data with baseline behavioral data that had been recorded over a 20-d period before the experimental treatment. Neither stereotypy nor grooming behavior varied as a result of exposure to music. These results do not support the hypothesis that auditory enrichment in the form of exposure to music is an effective means of reducing stereotypic behavior in O. garnettii.

Canine and feline tail amputation.

Abstract: This column outlines the indications, anesthetic and analgesic planning, surgical techniques, postoperative considerations and surgical risks for canine and feline caudectomy.

Sonographically guided placement of intravenous catheters in minipigs.

Abstract: Many procedures in minipigs require establishment of reliable deep venous access with a large-bore catheter. In animal experiments, such catheters are typically implanted surgically. In clinical settings, however, ultrasound imaging is routinely used to facilitate safe, minimally invasive puncture of deep vessels. The authors describe a technique for using ultrasound guidance to puncture and cannulate the minipig femoral vein. They carried out the procedure in six minipigs for the purpose of injecting contrast agents for subsequent imaging scans. The procedure was ultimately successful in all pigs, took 10 min on average and resulted in no physiological complications. In one minipig, however, a 10-cm-long catheter became dislodged from the femoral vein; use of a longer (25-cm-long) catheter was optimal for establishing reliable intravenous access.

A novel system for individually housing bullfrogs.

Abstract: A researcher at the authors' institution needed to house adult bullfrogs (Rana catesbeiana) individually. The authors responded to this need by modifying 5-gallon plastic buckets to use for individual housing of bullfrogs. These buckets provided a simple, inexpensive housing system that successfully maintained healthy and behaviorally normal frogs. The authors describe the housing and husbandry of the bullfrogs in this individual housing situation and recommend it for use by others.

Implementing a medical surveillance program for animal care staff.

Abstract: In animal research facilities, personnel may develop allergies or serious health problems as a result of exposure to chemical or biological agents. Medical surveillance is essential for evaluating the health of prospective or current employees and determining their risk of exposure to occupational hazards. The author discusses the role of institutional medical surveillance programs and presents considerations for implementing such programs.

Comparison of systemic Listeria monocytogenes infection in esophageally inoculated mice anesthetized with isoflurane or pentobarbital.

Abstract: In previous attempts to produce a murine model of gastrointestinal listeriosis, the authors observed that pentobarbital anesthesia greatly increased disease severity in mice that were esophageally inoculated with the bacterium Listeria monocytogenes. In this study, they sought to evaluate the severity of systemic infection in inoculated mice that were anesthetized with isoflurane, an inhalational agent that is safer than pentobarbital and more commonly used for rodent anesthesia. Compared with pentobarbital anesthesia, isoflurane anesthesia resulted in infections of lesser severity, similar to those observed in unanesthetized mice. A pilot study in which mice were anesthetized with isoflurane for 5, 10 or 20 min suggested that this effect was not related to the duration of anesthesia. These results show that isoflurane anesthesia administered for 5 to 20 min does not potentiate the severity of listeriosis infection in mice esophageally inoculated with L. monocytogenes.

Death and diarrhea in guinea pigs (Cavia porcellus).

Abstract: inflammatory cells, including lymphocytes and plasma cells; there was some distortion of normal mucosal architecture, with loss of regularly arranged crypts. Scattered within the mucosa were single or large numbers of cyst-like structures (Fig. 1). No notable lesions were found in sections of heart, lungs, spleen, liver, kidneys, stomach and duodenum. On the basis of the clinical signs, microbiologic analysis and histopathological findings, what do you think was the cause of diarrhea and death in the guinea pigs? How common is this condition? How would you treat it?