ANIMAL HEALTH ANIMAL HEALTH AND OBSERVATIONAND OBSERVATION

MICEMICE

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MICEMICE

Scientific Name – Scientific Name – Mus musculusMus musculus

Over 100 recorded inbred strains of miceOver 100 recorded inbred strains of mice Only 7 or 8 are commonly used in researchOnly 7 or 8 are commonly used in research

Variety of outbred mouse stocks are also Variety of outbred mouse stocks are also used in research.used in research.

MICE – USE IN RESEARCHMICE – USE IN RESEARCH

Used in wide variety Used in wide variety of research of research programs, including programs, including genetics, genetics, immunology and immunology and infectious disease infectious disease studies.studies.

MICE BEHAVIORMICE BEHAVIOR

Normally keep all 4 Normally keep all 4 feet on the floor and feet on the floor and when sleeping, will when sleeping, will curl its head under curl its head under its’ body.its’ body.

Usually, if housed Usually, if housed together in a group, together in a group, they will sleep they will sleep huddled together.huddled together.

MICE BEHAVIORMICE BEHAVIOR

Behaviorally Behaviorally dominant mouse can dominant mouse can bite or chew fur off a bite or chew fur off a subordinate mouse, subordinate mouse, usually in face regionusually in face region

(see picture) (see picture)

This is referred to as This is referred to as barberingbarbering which is which is usually harmless.usually harmless.

BEHAVIORBEHAVIOR

BarberingBarbering should not be should not be confused with fur loss confused with fur loss caused by skin or mite caused by skin or mite problems.problems.

Females usually don’t Females usually don’t fight.fight.

Group housed males Group housed males often fight. Aggressive often fight. Aggressive mice should be housed mice should be housed individually to avoid individually to avoid potential injury to potential injury to cagemates.cagemates.

Barbering

Fighting

IDENTIFICATIONIDENTIFICATION

Required by most investigators in order Required by most investigators in order to provide a means of tracking history of to provide a means of tracking history of each animal throughout the study.each animal throughout the study.

Temporary ID may includeTemporary ID may include Dye – applied to part of the bodyDye – applied to part of the body Clipped hairClipped hair Use of a marking penUse of a marking pen

IDENTIFICATIONIDENTIFICATION

Permanent IDPermanent ID Ear tags sometimes usedEar tags sometimes used

Small metal band with imprinted numbers that Small metal band with imprinted numbers that are pierced through ear and locked in placeare pierced through ear and locked in place

Mice tend to catch these on things and rip them Mice tend to catch these on things and rip them out.out.

Tattooing Tattooing Generally done on the tail.Generally done on the tail.

IDENTIFICATIONIDENTIFICATION

Ear punchEar punch Small metal device which produces small, Small metal device which produces small,

permanent holes in the animals’ ear.permanent holes in the animals’ ear. Standardized number chart can be utilized.Standardized number chart can be utilized.

Should be noted that it can be somewhat difficult Should be noted that it can be somewhat difficult to read another technicians’ ear notching as each to read another technicians’ ear notching as each persons ear notches may vary slightly and can persons ear notches may vary slightly and can be misread.be misread.

See handout for ear notching examples.See handout for ear notching examples.

IDENTIFICATIONIDENTIFICATION

Computer chips can also be used.Computer chips can also be used. Cage cards should be used as well. Cage cards should be used as well.

Should have the following informationShould have the following information StrainStrain Birth DateBirth Date SexSex Receiving DateReceiving Date SourceSource Investigator nameInvestigator name Animal #Animal #

HANDLING AND HANDLING AND RESTRAINTRESTRAINT

May pick up by grasping the tail or the May pick up by grasping the tail or the skin over the shoulders with fingers OR skin over the shoulders with fingers OR rubber-tipped forceps.rubber-tipped forceps. When picking up by tail, avoid the last third When picking up by tail, avoid the last third

of the tail. Pick up by base of tail.of the tail. Pick up by base of tail. If using forceps, remember to disinfect If using forceps, remember to disinfect

between animals.between animals. Mice tend to urinate and excrete a fecal pellet Mice tend to urinate and excrete a fecal pellet

when you manipulate them. Be prepared!when you manipulate them. Be prepared!

RESTRAINTRESTRAINT

Start by placing the mouse on a Start by placing the mouse on a surface it can grasp (such as surface it can grasp (such as cage top) while you hold near the cage top) while you hold near the base of the tail with your base of the tail with your dominant hand.dominant hand.

Grasp the loose skin over the Grasp the loose skin over the shoulders by the non-dominant shoulders by the non-dominant hand between thumb and first hand between thumb and first three fingers.three fingers.

Mouse must be held firmly but Mouse must be held firmly but gently, so it does not have gently, so it does not have difficulty breathing.difficulty breathing.

Note: The picture shown does not Note: The picture shown does not accurately show an individual accurately show an individual wearing appropriate PPE. They wearing appropriate PPE. They should be wearing gloves.should be wearing gloves.

RESTRAINTRESTRAINT Plastic restraint Plastic restraint

devices can also be devices can also be used.used. Used to hold mice for Used to hold mice for

longer periods of longer periods of time.time.

Device allows either Device allows either head or tail to head or tail to protrude for protrude for procedures.procedures.

Remember to Remember to disinfect between disinfect between animals.animals.

SEXINGSEXING

Males Males Have a greater Have a greater

ano-genital distanceano-genital distance Holds true for Holds true for

neonates, juveniles neonates, juveniles and adults.and adults.

Sexing in newborns is Sexing in newborns is best done by best done by comparing several comparing several animals at one time.animals at one time.

Male

Female

Appropriate PPE is not shown in these pictures.

HOUSINGHOUSING

May be housed in solid bottom shoe-box cages May be housed in solid bottom shoe-box cages with bedding, generally in groups.with bedding, generally in groups.

Solid bottom caging with bedding Solid bottom caging with bedding recommended.recommended. Provide mice with warmth, security, and nesting Provide mice with warmth, security, and nesting

material. material. Lids rest on top of the cage with locks or clamps.Lids rest on top of the cage with locks or clamps. Mouse lid wires placed closer together than rat Mouse lid wires placed closer together than rat

cages.cages. Change bedding no less than twice a week.Change bedding no less than twice a week.

HOUSINGHOUSING

Cage and animal room sanitation are very Cage and animal room sanitation are very important.important.

Need to follow SOPs per facilityNeed to follow SOPs per facility Examples - Examples - Solid bottom cages/accessories – 1-3 times per Solid bottom cages/accessories – 1-3 times per

weekweek Cage shelving – At least once per monthCage shelving – At least once per month Wire bottom cages – At least once every 2 Wire bottom cages – At least once every 2

weeksweeks

BEDDINGBEDDING

Should be non-toxic, Should be non-toxic, non-nutritive, non-nutritive, unpalatable, non-unpalatable, non-abrasive, absorbent abrasive, absorbent and inexpensive.and inexpensive. Processed wood Processed wood

chips chips Corn cob productsCorn cob products Shreddable paperShreddable paper

Alphi-Dri (paper) Aspen (hardwood)

Wood pellets

Sanichip (hardwood)

Carefresh (paper) Cellu-dri (paper)

DIETDIET Normally provided in the Normally provided in the form of pellets.form of pellets. Pellets are firm and Pellets are firm and

require gnawing require gnawing This helps keep their This helps keep their

continuously growing continuously growing incisors worn down.incisors worn down.

For programs which For programs which require critical disease require critical disease control measures, diet control measures, diet products which can be products which can be sterilized are available.sterilized are available. Diets already sterilized by Diets already sterilized by

irradiation can also be irradiation can also be purchased.purchased. Mouse with

normal incisorsMouse with overgrown incisors and malocclusion

DIET CONTINUEDDIET CONTINUED

Rodents generally fed Rodents generally fed ad libitumad libitum – given – given a continuous supply of food and water.a continuous supply of food and water.

Non-pelleted diets available – For use Non-pelleted diets available – For use when food intake being measured or when food intake being measured or when substances are being added.when substances are being added.

Food consumption – 3-6 grams, or 1.5 Food consumption – 3-6 grams, or 1.5 grams per 10 grams of body weight, per grams per 10 grams of body weight, per dayday

BREEDING INFORMATIONBREEDING INFORMATION

Sexual maturity – 40-60 days of ageSexual maturity – 40-60 days of age Gestation – 19-21 daysGestation – 19-21 days Litter size – 6-12Litter size – 6-12 Newborn litters should not be disturbed Newborn litters should not be disturbed

for a few days to prevent cannibalism by for a few days to prevent cannibalism by adults.adults.

Weaning – 21 days.Weaning – 21 days.

DISEASEDISEASE Tyzzer’s DiseaseTyzzer’s Disease TransmittedTransmitted

Fecal – oral routeFecal – oral route SymptomsSymptoms

HunchedHunched Unformed fecesUnformed feces Unkempt hair coatUnkempt hair coat DehydrationDehydration Can by asymptomaticCan by asymptomatic

FUR MITESFUR MITES Transmitted by direct contactTransmitted by direct contact Usually no clinical signsUsually no clinical signs

Alopecia may occurAlopecia may occur PruritisPruritis

Treatment Treatment DustsDusts IvermectinIvermectin