Being able to safely and effectively restrain mice and rats is an important part of conducting research. Working confidently and humanely with mice and rats requires a basic competency in handling and restraint methods. This article will present the basic principles required to safely handle animals. One-handed, two-handed, and restraint with specially designed restraint objects will be illustrated. Often, another part of the research or testing use of animals is the effective administration of compounds to mice and rats. Although there are a large number of possible administration routes (limited only by the size and organs of the animal), most are not used regularly in research. This video will illustrate several of the more common routes, including intravenous, intramuscular, subcutaneous, and oral gavage. The goal of this article is to expose a viewer unfamiliar with these techniques to basic restraint and substance administration routes. This video does not replace required hands-on training at your facility, but is meant to augment and supplement that training.

In situ breast cryosurgery has been proved to be feasible and efficacious in small and large animal studies and has been successfully performed in 1 patient with breast cancer. The results of this study suggest that ultrasound-guided cryosurgery of breast cancer warrants further investigation.

Two isolator caging systems were evaluated against challenge with MHV-Y, an enterotropic strain of mouse hepatitis virus. The systems were similar in that they both used an identical shoebox cage equipped with a polycarbonate filter top incorporating a Reemay filter. They differed in that one system supplied HEPA-filtered air through a grommet in the filter lid so that the cage was pressurized slightly. A rack holding 60 cages (30 front and back) was utilized. Thirty cages without filter tops housed one mouse each that had been infected orally with 19,000 ID50 of MHV-Y and an uninfected cagemate. The remaining 30 cages, each housing 2 uninfected mice were divided into 3 groups of 10 cages. Group I cages (controls) had no filter top; Group II cages were equipped with filter tops; and Group III were equipped with filter tops and intracage HEPA-filtered air. The cages housing uninfected mice were interspersed between, above, below and behind cages housing infected mice. The uninfected mice were maintained in contact with the MHV-Y infected mice for 8 weeks. Transmission of MHV-Y was determined serologically by indirect ELISA. All mice housed within the Group I cages (control) seroconverted to MHV, while only 4 mice (2 cages) seroconverted in Group II, and no mice seroconverted in Group III.

Filter-top cages, while effective in reducing cross contamination by particulate material including microbes, can also cause accumulation of the waste gases carbon dioxide and ammonia as well as increased intracage relative humidity. A prototype system which provided each cage with 23 air changes per hour through a nozzle inserted in the filter lid was evaluated. The ventilated cageing system was effective in reducing intracage carbon dioxide, ammonia and relative humidity levels. Mean weekly carbon dioxide levels were 2900 ppm lower, ammonia levels 240 ppm lower and intracage relative humidity levels 8% lower in the ventilated cages than in unventilated controls.

Group G streptococci which have been isolated from the oral fora of rats are also normal inhabitants of the human skin, oropharynx, gastrointestinal tract, and female genital tract. This group of streptococci can cause a wide variety of clinical diseases in humans, including septicemia, pharyngitis, endocarditis, pneumonia, and meningitis. Ten days after oral gavage with 7,12-dimethylbenz[a]anthracene, 12 of 22 two-month-old, female, outbred, viral-antibody-free rats presented with red ocular and nasal discharges and marked swelling of the cervical region. Various degrees of firm, nonpitting edema in the region of the cervical lymph nodes and salivary glands as well as pale mucous membranes and dehydration were observed. Pure cultures of beta-hemolytic streptococci were obtained from the cervical lymph nodes of three rats that were necropsied. A rapid latex test system identified the isolates to have group G-specific antigen. These streptococcal isolates fermented trehalose and lactose but not sorbitol and inulin and did not hydrolize sodium hippurate or bile esculin. A Voges-Proskauer test was negative for all six isolates. Serologic tests to detect the presence of immunoglobulin G antibody to rat viral pathogens and Mycoplasma pulmonis were negative. Histopathologic changes included acute necrotizing inflammation of the cervical lymph nodes with multiple large colonies of coccoid bacteria at the perimeter of the necrotic zone. To our knowledge, this is the first report of naturally occurring disease attributed to group G streptococci in rats.