Bone marrow transplantation (BMT) is the treatment of choice for many leukemias, solid tumors, and metabolic diseases. The field of bone marrow research is highly dependent on in vivo experimentation, because in vitro techniques do not mimic these complicated in vivo systems. Therefore, understanding the medical and husbandry care needs of these transiently immunodeficient bone marrow recipient animals is crucial for researchers, veterinary and animal care personnel. Here we discuss the principles of bone marrow transplantation, mouse pathogens that can interfere with transplantation research, and important husbandry and veterinary practices for mice that may help to minimize unnecessary infections during the transplantation process. Whole-body irradiation is one of the most common tools for myeloablation of the recipient's bone marrow. We discuss the crucial role of the irradiator for BMT research and the importance of aseptic husbandry practices to lessen the possibility of the irradiator for being a source for disease transmission. Finally, we discuss some important guidelines for Institutional Animal Use and Care Committees reviewing irradiation and BMT protocols.

Exposure to CO₂ is a common method used to euthanize rodents in biomedical research and rodent production. The purpose of this study was to determine the length of CO₂ exposure required to euthanize neonatal rats (0 to 10 d old). Multiple groups of rats were exposed to 100% CO₂ for 5 to 60 min. After CO₂ exposure, rats were placed in room air for 20 min to allow for possible recovery. No difference was found in comparing 1 inbred strain and 1 outbred stock of rats. Time to death varied inversely with the age of the animals, requiring as long as 35 min on the day of birth. The time to death decreased steadily with increasing age, with 100% of the rats euthanized after 5 min of CO₂ exposure at 10 d of age. The time required for 100% mortality decreased by 3 min for every 1 d increase in age between days 0 and 10.

Tricaine methanesulfonate (MS222) injected into the intracoelomic cavity of reptiles was evaluated as a chemical euthanasia method. Three western fence lizards, 2 desert iguanas, 4 garter snakes, and 6 geckos were euthanized by intracoelomic injection of 250 to 500 mg/kg of 0.7% to 1% sodium-bicarbonate–buffered MS222 solution followed by intracoelomic injection of 0.1 to 1.0 ml unbuffered 50% (v/v) MS222 solution. A simple 2-stage protocol for euthanasia of reptiles by using MS222 is outlined. In addition, the conditions for safe use of MS222 are discussed. MS222 offers an alternative to sodium pentobarbital for euthanasia of reptiles.

Investigators are obligated to optimize the perioperative care of experimental animals, but little is known about the effects of anesthesia and surgery on serum chemistries in KCG pigs. The objective of this study was to examine the influence of fasting and surgery under general anesthesia on 27 serum chemistries in KCG miniature pigs to improve management. Crossbred KCG minipigs were used at a mean of 12.3 mo of age (range, 8.6 to 14.9) and 33.4 kg of body weight (range, 24.0 to 40.2). Serum chemistries were evaluated at the start and end of a 24 h fasting period in fasted animals (n = 6). No significant differences were observed between the starting and postfasting studies. Partial hemilaminectomy of the lumbar spine was carried out in 2 groups of animals. Those given sevoflurane anesthesia (n = 7) had significant decreases in serum albumin, potassium, inorganic phosphorus, γ-glutamyltransferase peptidase, cholinesterase, and glucose postoperatively compared with preoperative values. Animals given isoflurane (n = 7) anesthesia had significantly decreased total protein, albumin, triglyceride, phospholipids, sodium, potassium, calcium, alanine aminotransferase, alkaline phoshatase and glucose after surgery compared with levels before surgery. In a separate experiment (n = 7), serum glucose and insulin also decreased during the postoperative period after isoflurane anesthesia. These results demonstrate that select serum electrolytes, glucose, and insulin of KCG miniature pigs are altered after general anesthesia. Investigators must be aware of the effects of anesthetic agents on experimental animals to provide optimal care and for interpretation of experimental data.

Traditional protocols for sperm recovery, cryopreservation, and in vitro fertilization (IVF) have been considerably less efficient for inbred mouse strains, including C57BL/6, than for hybrid and outbred strains. We report here that 3 changes to published and widely used protocols markedly improved fertilization rates for both fresh and frozen–thawed sperm in 3 substrains of C57BL/6 mice (C57BL/6J, C57BL/6NCrl, and C57BL/6NTac). First, the traditional cyroprotective agent was modified by adding amino acids. Second, preincubation of sperm in a preincubation medium containing methyl-β-cyclodextrin and polyvinyl alcohol enabled collection of progressively motile sperm for IVF. Third, we evaluated 3 media for IVF: human tubal fluid (HTF), modified Krebs–Ringer bicarbonate medium (TYH), and minimal essential medium (MEM). HTF and TYH were modified by adding minimal essential amino acids. The methodology reported here increased the IVF rate of both fresh and frozen–thawed sperm and enabled efficient isolation of capacitated viable sperm. Fertilization rates greater than 65% and 40% were obtained with the 3 tested substrains when fresh and frozen–thawed sperm, respectively, were used for IVF. Higher fertilization rates were seen with frozen–thawed sperm from C57BL/6NCrl and C57BL/6NTac mice than from C57BL/6J mice. Among all strains, fresh sperm from C57BL/6NTac mice gave the highest fertilization rate. Of 190 two-cell embryos, 63 (33.2%) developed to term after transfer to pseudopregnant recipient mice. The protocol we detail here provides reliable cryopreservation and recovery of live mice in 3 substrains of C57BL/6, making sperm cryopreservation and IVF a viable choice for preservation and distribution of mouse lines.

A novel surgical method for collecting oocytes from unique and irreplaceable mice is described. This method, surgical oocyte retrieval (SOR), facilitates the collection of ovulated oocytes, does not require euthanasia, and preserves reproductive potential. The surgery involves a small incision in the ampulla region of the oviduct, through which the cumulus oocyte mass is removed with a gel-loading pipette. The incision then is closed by using a tissue adhesive, which is required to ensure healing of the incision and containment of any oocytes ovulated after SOR. Two anesthetics, isoflurane and tribromoethanol, were compared for oocyte toxicity during SOR. More dead oocytes were recovered when tribromoethanol was used than when isoflurane was used. Combining SOR and traditional oocyte collection methods yielded more oocytes per BALB/cByJ than did traditional methods alone (41 versus 28 oocytes, respectively). Oocytes collected by using SOR were fertilized and subsequent embryos developed to term comparable to controls. This technique provides an alternative method for oocyte collection and will be valuable for maximizing the number of oocytes from irreplaceable mice.

We developed a compact culture device that maintains developing embryos in vitro under constant temperature and CO₂ concentration. Using this device, we cultured rabbit embryos from the pronuclear stage to the hatched blastocyst stage and recorded their development digitally for 7 d. Recorded images were converted to a movie, and the developmental movement of individual embryos was analyzed. With this culture system, we can observe embryonic development in a suitable environment continuously for several days; similar long-term observation is not possible in the conventional system. The proportion of embryos that developed from the pronuclear stage to the blastocyst stage was the same in the new system (73.1%; 38 of 52) as in the conventional (control) system (77.6%; 38 of 49). Compaction of embryos occurred from the 8-cell to the morula stage at 32.5 ± 0.71 h after insemination. The time of blastocyst formation (77.2 ± 3.2 h after insemination) varied somewhat between embryos. Average hatching time was 98.7 ± 4.4 h after mating. Therefore, the cleavage, blastomere movement, and hatching processes of blastocysts can be followed clearly and recorded by using this new culture system.

Thirty-nine captively reared fat-tailed jirds (Pachyuromys duprasi) were enrolled in a minimally invasive study to determine an effective venipuncture technique and establish normal serum biochemistry parameters. A jugular venipuncture technique using chemical restraint (ketamine, 30 mg/kg; xylazine, 6 mg/kg; acepromazine, 1 mg/kg) administered intraperitoneally was safe and consistently yielded at least 0.3 mL of blood. Of the biochemical indicators measured (glucose, total protein, albumin, globulin, alkaline phosphatase, alanine transferase, total bilirubin, amylase, BUN, creatinine, calcium, phosphorous, sodium and potassium), amylase and glucose levels differed significantly between male and female fat-tailed jirds.

The open-drop technique is used frequently for anesthetic delivery to small rodents. Operator exposure to waste anesthetic gas (WAG) is a potential occupational hazard if this method is used without WAG scavenging. This study was conducted to determine whether administration of isoflurane by the open-drop technique without exposure controls generates significant WAG concentrations. We placed 0.1, 0.2, or 0.3 ml of liquid isoflurane into screw-top 500 or 1000 ml glass jars. WAG concentration was measured at the opening of the container and 20 and 40 cm from the opening, a distance at which users likely would operate, at 1, 2, or 3 min WAG was measured by using a portable infrared gas analyzer. Mean WAG concentrations at the vessel opening were as high as 662 ± 168 ppm with a 500 ml jar and 122 ± 87 ppm with a 1000 ml jar. At operator levels, WAG concentrations were always at or near 0 ppm. For measurements made at the vessel opening, time was the only factor that significantly affected WAG concentration when using the 500 ml jar. Neither time nor liquid volume were significant factors when using 1000 ml jar. At all liquid volumes and time points, the WAG concentration associated with using the 500 ml container was marginally to significantly greater than that for the 1000 ml jar.

Institutions worldwide have experienced a rapid growth in the use of zebrafish as a research model for a variety of molecular and genetic studies of vertebrate development. This expansion in zebrafish research essentially has outpaced the establishment of specific recommendations for the care and use of fish in research. In some cases, this situation has created a dilemma where an Institutional Animal Care and Use Committee, which is responsible for oversight of vertebrate animal research, is not fully prepared to undertake this role for a decentralized zebrafish facility. IACUC inspectors will be more equipped to ask pertinent questions by understanding the basic principles of zebrafish health and facility management. Concurrently, zebrafish facility managers can contribute to the progress of a semiannual facility inspection by maintaining fully accessible operating records. In the context of presenting a well-established and useful model of zebrafish management and recordkeeping to the zebrafish facility operator, the information we present here also prepares a potential IACUC inspector to conduct a constructive and positive inspection.

A pregnant 7-y-old Beagle crossbred dog (Canis familiaris) presented with clinical signs of lethargy, dehydration, and occasional vomiting. The dog was managed with fluids, antibiotics, and supportive care for several days in an effort to maintain the pregnancy. The bitch aborted the pups at approximately 50 d of gestation and was euthanized due to her poor reproductive performance and age. Necropsy revealed a compact mass of plastic pieces in the pylorus of the stomach. The gastric foreign body was discovered to be the vinyl covering of a bed that was in the dog's run as part of the environmental enrichment program for this animal. The use of that type of dog bed was discontinued. This case emphasizes that any type of enrichment can cause harm and the risks must be assessed carefully before implementing any enrichment device.