ANIMAL HEALTH AND OBSERVATION MICE This workforce solution was funded by a grant awarded under the President’s Community-Based Job Training Grants as implemented by the U.S. Department of Labor’s Employment and Training Administration.  The solution was created by the grantee and does not necessarily reflect the official position of the U.S. Department of Labor.  The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership.  This solution is copyrighted by the institution that created it.  Internal use by an organization and/or personal use by an individual for non-commercial purposes is permissible.  All other uses require the prior authorization of the copyright owner.

MICE Scientific Name – Mus musculus Over 100 recorded inbred strains of mice Only 7 or 8 are commonly used in research Variety of outbred mouse stocks are also used in research.

MICE – USE IN RESEARCH Used in wide variety of research programs, including genetics, immunology and infectious disease studies.

MICE BEHAVIOR Normally keep all 4 feet on the floor and when sleeping, will curl its head under its’ body. Usually, if housed together in a group, they will sleep huddled together.

MICE BEHAVIOR Behaviorally dominant mouse can bite or chew fur off a subordinate mouse, usually in face region (see picture) This is referred to as barbering which is usually harmless.

BEHAVIOR Barbering should not be confused with fur loss caused by skin or mite problems. Females usually don’t fight. Group housed males often fight. Aggressive mice should be housed individually to avoid potential injury to cagemates. Barbering Fighting

IDENTIFICATION Required by most investigators in order to provide a means of tracking history of each animal throughout the study. Temporary ID may include Dye – applied to part of the body Clipped hair Use of a marking pen

IDENTIFICATION Permanent ID Ear tags sometimes used Tattooing Small metal band with imprinted numbers that are pierced through ear and locked in place Mice tend to catch these on things and rip them out. Tattooing Generally done on the tail.

IDENTIFICATION Ear punch Small metal device which produces small, permanent holes in the animals’ ear. Standardized number chart can be utilized. Should be noted that it can be somewhat difficult to read another technicians’ ear notching as each persons ear notches may vary slightly and can be misread. See handout for ear notching examples.

IDENTIFICATION Computer chips can also be used. Cage cards should be used as well. Should have the following information Strain Birth Date Sex Receiving Date Source Investigator name Animal #

HANDLING AND RESTRAINT May pick up by grasping the tail or the skin over the shoulders with fingers OR rubber-tipped forceps. When picking up by tail, avoid the last third of the tail. Pick up by base of tail. If using forceps, remember to disinfect between animals. Mice tend to urinate and excrete a fecal pellet when you manipulate them. Be prepared!

RESTRAINT Start by placing the mouse on a surface it can grasp (such as cage top) while you hold near the base of the tail with your dominant hand. Grasp the loose skin over the shoulders by the non-dominant hand between thumb and first three fingers. Mouse must be held firmly but gently, so it does not have difficulty breathing. Note: The picture shown does not accurately show an individual wearing appropriate PPE. They should be wearing gloves.

RESTRAINT Plastic restraint devices can also be used. Used to hold mice for longer periods of time. Device allows either head or tail to protrude for procedures. Remember to disinfect between animals.

SEXING Males Have a greater ano-genital distance Holds true for neonates, juveniles and adults. Sexing in newborns is best done by comparing several animals at one time. Female Appropriate PPE is not shown in these pictures. Male

HOUSING May be housed in solid bottom shoe-box cages with bedding, generally in groups. Solid bottom caging with bedding recommended. Provide mice with warmth, security, and nesting material. Lids rest on top of the cage with locks or clamps. Mouse lid wires placed closer together than rat cages. Change bedding no less than twice a week.

HOUSING Cage and animal room sanitation are very important. Need to follow SOPs per facility Examples - Solid bottom cages/accessories – 1-3 times per week Cage shelving – At least once per month Wire bottom cages – At least once every 2 weeks

BEDDING Should be non-toxic, non-nutritive, unpalatable, non-abrasive, absorbent and inexpensive. Processed wood chips Corn cob products Shreddable paper Alphi-Dri (paper) Aspen (hardwood) Wood pellets Sanichip (hardwood) Carefresh (paper) Cellu-dri (paper)

DIET Normally provided in the form of pellets. Pellets are firm and require gnawing This helps keep their continuously growing incisors worn down. For programs which require critical disease control measures, diet products which can be sterilized are available. Diets already sterilized by irradiation can also be purchased. Mouse with normal incisors Mouse with overgrown incisors and malocclusion

DIET CONTINUED Rodents generally fed ad libitum – given a continuous supply of food and water. Non-pelleted diets available – For use when food intake being measured or when substances are being added. Food consumption – 3-6 grams, or 1.5 grams per 10 grams of body weight, per day

BREEDING INFORMATION Sexual maturity – 40-60 days of age Gestation – 19-21 days Litter size – 6-12 Newborn litters should not be disturbed for a few days to prevent cannibalism by adults. Weaning – 21 days.

DISEASE Tyzzer’s Disease Transmitted Symptoms Fecal – oral route Hunched Unformed feces Unkempt hair coat Dehydration Can by asymptomatic

FUR MITES Transmitted by direct contact Usually no clinical signs Alopecia may occur Pruritis Treatment Dusts Ivermectin