Comments & suggestions  should be directed to Visit my website Housing Cage space requirements for mice as listed in the Guide are shown below. Body weight  (g) Floor area per animal (in2) Cage height (in)       <10 6.0 5.0      10-15 8.0 5.0      15-20       12.0 5.0       >25 minimum 15 5.0 Bedding material provides thermal insulation, absorbs fecal and urinary wastes, and in some instances is used for nest construction.  The material chosen should be absorbent, not readily eaten, free of infectious agents and injurious substances, and comfortable for the animals. Bedding may consist of paper, hardwood chips, or corn cob materials.  The use of aromatic wood shavings such as pine and cedar shavings should be avoided in the laboratory setting as it induces activation of hepatic microsomal enzymes, and may interfere with experimental results.  Dusty bedding should not be used for housing mice as dust may result in preputial or respiratory problems.  Only autoclaved bedding should be used for immunodeficient animals to prevent the introduction of opportunistic infectious agents. The amount of bedding material provided is important.  Too much material combined with  digging and piling activities typical of  mice can result in contact with the water source and a flooded cage.  Avoid the use of materials like cotton or shredded paper in breeding cages because the pups can become entangled in the fibers, and may suffocate or lose appendages. The temperature in the animal room should range from 64° to 79°F (18° to 26°C) with an average temperature of 72° (22°C).  Mice that are singly housed may require slightly increased temperatures for comfort.  The relative humidity in mouse rooms should be between 40% and 70%.  The temperature and humidity conditions of the mouse room are important as low humidity (less than 40% ) and high temperature (greater than 80°F) can result in a condition known as ringtail.  Ringtail is characterized by the appearance of concentric rings around the tail and frequently results in sloughing of all or part of the tail.  The feet may also be swollen and reddened in affected mice.  A combination of low humidity and cold temperature can result in tail gangrene. To ensure proper ventilation and removal of ammonia and odors, the minimum number of air changes per hour should be 10 - 15.  In some situations a greater number of air changes per hour may be required to maintain good air quality.  The constant presence of the odor of ammonia indicates that rooms are overcrowded or that a greater number of air changes are needed.  Keep in mind that the air in cages, will be 1°- 4°F warmer, 5% - 10% more humid, and have a greater concentration of ammonia than the surrounding room air. Animal rooms should be regulated by automatic timers to provide cycles with 12 -14 hours of light and 10 - 12 hours of dark.  The recommended intensity of light in the room is 100 foot-candles at the working level; however, this is for the worker and not for the mouse.  Light levels of 30 foot-candles are recommended for albino animals to avoid retinal damage.  Keep in mind that mice on the lower racks will receive less light than those housed on the top racks.  Mice are capable of detecting a wide range of auditory frequencies, and can hear both audible sounds and ultrasound frequencies.  Ultrasound frequencies are used by mice to communicate during sexual activities, and are also the frequencies of infant distress calls.  Audible sound is used in aggressive and defensive behaviors.  Noise in the animal facility is a consideration for the management of mice, as audiogenic seizures may occur in some strains of mice exposed to sudden, loud noise stimuli. Diet and Nutrition Mice in research facilities are generally fed a pelleted rodent diet ad libitum.  Maintenance diets generally contain 4 - 5% fat and 14% protein.  Young animals and those used for breeding have higher nutrient requirements; therefore, diets for these animals contain 7 - 11% fat and 17 - 19% protein.  An adult mouse will consume about 15 grams of feed per 100 grams of body weight per day.  Food for immunodeficient rodents should be autoclaved or irradiated to prevent introduction of infectious agents.  Young mice may not be able to reach the food, so it is acceptable to put food on the floor of the cage until they are able to eat from the hopper.  If the food is too hard for young mice to chew, it may be moistened.  Food should not be used more than 6 months after the milling date. Water may be provided by bottles and sipper tubes or by automatic watering systems.  Cages should be checked every day to ensure that water is not leaking into the cage and soaking the bedding as wet mice become hypothermic very rapidly.  An adult mouse will consume about 15 ml of water per 100 grams of body weight per day.  Mice dehydrate very rapidly when they do not have access to water.  Young mice may require a longer sipper tube in order to reach the water source. Animal Identification Identification schemes vary according to the needs of the researcher.  Cage card identification may be adequate for many circumstances; however, more precise methods may be required when individuals within a cage need to be readily identifiable.  Ear notching is probably the most commonly used technique.  Fighting may on occasion obliterate their numbers by chewing on the ears, but in general this system works well.  Appropriately sized, numbered metal ear tags may also be used.  Freeze branding and tattooing are less practical methods due to the small size of mice but are sometimes employed.  Toe clipping may only be used to identify neonates. Temporary identification of a mouse may be accomplished by dying the fur, clipping the fur, or marking the tails with an indelible marker.  Subcutaneously implanted microchips can also be used to identify individual animals. Acclimatization Transportation of animals is stressful and leads to physiologic changes, such as increased cortisol levels, which may potentially alter research results.  Mice received from another site need to have adequate time to recover from shipping stress, and the length of time required may depend on the distance/time involved in transporting the mice.  Generally a minimum of 48 hours is required for blood cortisol levels to return to baseline values.  A quarantine/holding period allows the mice to adapt to their new surroundings and permits observation for any signs of infectious disease.