Presentation on theme: "The University of Texas at Tyler"— Presentation transcript:
1 The University of Texas at Tyler Institutional Animal Care and Use Committee:Working with the Laboratory Mouse*Note: Content not specific to UT Tyler is from the American Association for Laboratory Animal Science (AALAS)
2 Working with the Laboratory Mouse The goal of this course is to provide information on the use of mice in research. This course will address:Regulatory requirementsOccupational Health and SafetyHousing and Routine CareAnimal IdentificationSex DeterminationClinical Signs of IllnessHumane EndpointsEuthanasia
3 Regulatory Requirements To ensure the humane treatment of laboratory animals, animal research is regulated by two federal agencies:The United States Department of Agriculture (USDA) / Animal Care enforcing the Animal Welfare Act RegulationsThe National Institutes of Health / Office of Laboratory Animal Welfare (OLAW) enforcing the PHS PolicyThe Animal Welfare Act Regulations and the PHS Policy mandates differ greatly with respect to the laboratory strains of mice and rats. These species are not covered by the USDA but are included in PHS regulations and policy.
4 Regulatory Requirements The UT Tyler IACUC has policies and procedures on the use of animals that reflect federal and other government mandates and professional standards in the laboratory animal field—refer to the UT Tyler IACUC Policy Handbook available at:
5 Occupational Health & Safety Public Health Service Policy The Public Health Service Policy requires institutions to have an occupational health and safety program for individuals working with laboratory animals. This requirement is also reiterated in the Guide.It is the responsibility of principal investigators to ensure that their laboratory staff are informed of and participate in UT Tyler’s occupational health and safety program.
6 Occupational Health and Safety: Hazards of Working with Mice Working with mice is associated with the following hazards which will be described more fully in the following pages:InjuriesAllergiesZoonoses
7 Occupational Health & Safety Injuries and Allergies Personnel handling a mouse can be bitten if the animal is poorly restrained. Though mice are often inclined to bite when frightened, their incisors do not always break the skin.Poor technique in handling and restraining a mouse may also cause injury to the mouse.Training staff to work effectively and humanely with mice is essential to prevent injuries to people and mice.AllergiesPeople can develop an allergy to rodents after having contact with them for some time.Persons who develop allergy symptoms should seek medical counseling and may have to discontinue working with this species.
8 Housing and Routine Care: Animal Crowding Animal crowding in a cage affects environmental quality (the accumulation of urine, for example, leads to excess ammonia and moisture).Crowding can also cause newborn pups to be injured or killed. Crowding is a special concern for multiple litters in a cage since pups grow very quickly and rapidly increase their output of excreta.In particular, if the mother is about to give birth to a second litter, the first litter should be weaned and removed to new cages to prevent smothering and trauma of the newborns.
9 Routine SanitationRoutine sanitation and environmental controls are necessary for protecting animal health and for minimizing the introduction for non-experimental variables which could undermine the quality of research data.Sanitation schedules vary according to the type of mouse caging.Based on the types of caging and bedding in use at your facility, your institution will have a standard operating procedure (SOP) on the sanitation schedule for mouse cages.
10 Environmental Controls The Guide for the Care and Use of Laboratory Animals establishes standards for laboratory animal environments in regard to:room temperaturehumidityventilationillumination and light schedulenoise abatementThe details of these standards are generally not a concern to researchers who house their animals in an institutional animal facility, because it is the animal care staff who have the responsibility of operating the facility in compliance with these environmental standards.For practical considerations due to common work hours, researchers should be aware of the lighting schedules used in the rodent housing rooms (commonly 12 hr light:12 hr dark or 14 hr light:10 hr dark).If researchers working late turn on the lights in the animal rooms during the dark period, the disruption of the light schedule may cause the animals to be perturbed, which may have effects on breeding performance and on circadian rhythms.
11 Animal Handling and Restraint It's important to remember the following:As a small animal, mice can be easily injured if handled roughly. You should learn how to handle them firmly but gently and with confidence to avoid injuring these delicate animals.Mice are inclined to become aggressive and bite. Although their teeth seldom break through your skin, a bite can hurt! Develop your confidence in handling mice by learning from an experienced mentor and practice hand restraint first on anesthetized mice.
12 Animal Handling and Restraint If a mouse does bite you, train yourself not to fling the animal from your hand as a fall can hurt the animal and cause the loss of an animal and possible future genetic contamination of strains and stocks.Instead, remember that the mouse has bitten you in fear and self-defense. At that moment, you and the mouse share a mutual desire to disengage from each other.The best way to remove a mouse that is hanging on to your finger is to train yourself to lower your hand back into its cage. Presented with a retreat to its home cage, the mouse will quickly jump off your finger.
13 Animal Handling and Restraint The succeeding screens will show:Common approaches for hand restraint of mice.Two devices commonly used to restrain mice.
14 Hand RestraintThere are two common hand methods for restraining mice. No matter how you will restrain the mouse, mice are picked up the following way:If your mice are in barrier or containment housing, please open their cages in an appropriate hood or laminar-flow workbench.Remove the cage top if they are housed in a filter-top cage.Place the wirelid top sideways on top of the cage.Pick up a mouse by the tail (away from the tail tip) and lift the mouse directly to the wirelid. You will find that the wirelid is a useful area to which the mouse will want to hang on with its front feet, allowing you the opportunity to reposition your grasp.
15 Tail Wrap MethodIn the tail wrap method, you transfer the tail from your thumb and forefinger to the 4th and 5th fingers of the same hand. These fingers press into your palm the mouse's tail, close to the animal's rump. Then, your thumb and forefinger grasp a scruff of skin at the occiput of the mouse. In this method, the mouse is held by two points: the occiput and the base of the tail. To further immobilize the hindquarters, you may gently entrap one leg along with the tail beneath your 5th finger. It is important to provide back support to the mouse and avoid hyperextension of its back.
16 Points to remember: When picking up a mouse – Pick up the tail at the middle, not the tip. A mouse does not need to be picked up at the base of the tail like a rat does, because the mouse is light and its weight will not damage its tail.Never dangle a mouse by its tail, but instead lift it directly to the cage wirelid or some other support. When dangled, mice appear anxious as seen by the their behavior in hyperextending their feet.Mice feel more secure when given a protective cover, e.g., by an overturned cup-like device. This is a means to hold a mouse securely and comfortably for a few moments.If you need a place to briefly sort and hold your mice, say while you are rapidly administering injections to a cage of mice, each mouse can be placed on the wirelid after its injection. Mice will stay on their wirelid a short while if food blocks are present, due to their instincts for food. If you quickly make all your injections, all the mice can be treated without a mixup of repeated or skipped administrations.
17 Determining Sex and Age Refer to the image below: the top two mice are neonates and note that the anogenital distance is larger in the male than in the female neonates, the penis and vulva cannot be easily differentiated and so are referred to as a genital papilla. The bottom two animals are adults; genitalia are differentiated.
18 Determining Sex and Age Also, nipples become evident in females at about 10 days of age.Male mice, like other rodent species, retain an open inguinal canal in adulthood. That is, the descended testicles communicate with the abdominal cavity. Depending on the position in which the mouse is held, the testicles may be retracted into the abdomen or descended into the scrotum.Because of the open inguinal canal, castration of mice requires that the surgeon use caution when applying tension to the testicle. Too much tension can result in the intestines being pulled through the inguinal canal.
19 Determining Sex and Age Occasionally people experience difficulty in determining gender in mice at weaning age, although the anogenital distances are markedly different between males and females.Newborns have a subtle difference in the anogenital distance, due to their small size and scale of the anatomical landmarks. In determining the gender of newborns, it’s best to examine several animals side by side to distinguish the males from the females.The difference becomes more apparent after a few days of age. Another landmark is the presence of nipples in the females from 10 days of age, which are absent in the male. Darker mice are more difficult to differentiate than light colored mice.
21 Sex and Age Newborn through Day 5 The images on the next slide show pups from 1 to 5 days of age. (The following slides show mouse pups from 6 to 15 days of age.)Newborn, or 1 day old, mice are very red, helpless, and hairless. Because of their color and lack of hair, they are often referred to as pinkies.
27 Reproductive Data Of Mice StageSexual maturityEstrous cycleGestationWeaning ageReproductive lifeLife spanPups begin eatingdry foodAge40-60 days4 – 5 days21 days21-30 days±8 months1 - 3 years12 – 14 days
28 Minimizing Pain and Distress WHEREVER POSSIBLE, PAIN/DISTRESS SHOULD BE ELIMINATED!Clinical Signs of IllnessAchieving humaneness in animal research depends upon the control and, whenever possible, the reduction of animal pain and distress.Minimizing pain and distress also reduces the impact of these extraneous factors on the research, i.e., as sources of non-experimental variation.For example, in a mouse model of experimental autoimmune encephalomyelitis, implementation of supportive treatment (hydration and nutrition) was shown to protect against loss of body weight and to greatly extend survival of the animals in the study, from 25 to 60 days. (Ref.: Lab Animal, 29(5): 40-46, 2000.)
29 Minimizing Pain and Distress Causes of Pain and Distress in MiceResearch staff should be familiar with the causes of animal pain and distress. Pain and distress are caused by spontaneous and experimentally-induced disease or injury.Many factors may contribute to an animal’s distress or discomfort, including extreme homeostatic challenges.Pain/distress should be minimized to an extent that is possible and compatible with experimental objectives.
30 Factors in Pain & Distress Changes in the following parameters may cause or be associated with animal pain or distress:temperature (environmental and body temperature)hypoxiaedemablood electrolytes, e.g. hyperkalemiadehydrationenvironmentcagingcage mateslightinghumiditynoiseVibrationNote - Smaller mammals experience physiologic changes such as starvation (due to high metabolic rate) and chilling (due to large ratio of body surface area to mass) faster than larger animals.
31 Signs of Pain and Distress Signs of pain and distress in rodents are not easy to detect because of their body size, their tendency to conceal outward signs of pain and distress, and their habit of hiding or freezing when disturbed.Nevertheless, signs of pain or distress can be detected in rodents by carefully observing subtle changes in behavior.The ability to properly assess pain and distress in rodents requires:--knowledge of normal rodent behavior and appearance--a systematic approach to observing clinical signs in rodents
32 Assessing Appearance and Behavior From the Cage ExteriorRoutinely inspect the rodents through the top and sides of the cage. Get in the habit of removing the cage from the shelf and looking through all sides of the cage. Signs of distress may be missed in animals on lower or upper shelves because of low lighting or difficult access.Baby mice and rats can be inconspicuous within piles of bedding or nestboxes.Cage Wirelid OffLift the cage wirelid to elicit a response to your presence. This disturbance may prompt the animals to move about the cage. Examine the animals’ behavior, gait, and hair coat.Normal mice are inquisitive and explore their cage perimeter.
33 Behaviors to ObserveAbnormal mice may huddle in their cage, or they may fail to move around and explore their cage. In addition, mice may vocalize when approached.Inspect the animal’s mode and speed of movement. Observe the tail position when the animal moves.Is the gait (how it walks) awkward? Observe how all limbs move while walking.Does the animal teeter or stumble?Is the animal’s back hunched and abdomen tucked while walking?Is the tail held stiff and upright? Or does the tail drag?Tip: Observe a cage of normal animals for a comparison.Examine (and treat) an individual mouse by gently restraining the animal. You can move the animal to a separate examination box for detailed clinical inspection.
34 Red TearsStressed mice and rats commonly display red tears or porphyrin staining. Porphyrin is an oily discharge from the Harderian glands located in the orbit behind the eyes.Porphyrin staining may be seen:on the nose,around the eyelids,or on the medial aspect of the forepaws that become stained through grooming of the face.Affected rodents may also fail to groom or they may have piloerection of the hair coat (giving a spiky appearance to the hair).
35 Types of ObservationsA common approach to assessing animal appearance and behavior is through observation of the following:Activity Levele.g., hypoactivity (hunched, huddled, lethargic), hyperactivity, restlessness, lack of inquisitiveness Attitudee.g., arousal, depression, awareness of surroundings Behavior, Spontaneouse.g., vocalization, self-trauma, isolation from cage mates. These observations are made without disturbing the animal. Behavior, Provokede.g., vocalization, hiding, aggressiveness, minimal response. These observations are made when the animal is disturbed or even prodded.
36 Types of Observations Body Condition e.g., emaciation, missing anatomy Food and Fluid Intakee.g., elimination of feces and urine Fur and Skine.g., unkempt or greasy or dull fur; porphyrin staining around eyes and nostrils; cyanotic, pale, or congested mucous membranes or skin (ears, feet, tail); skin lesions; soiled anogenital area Eyese.g., clarity/condition of lens, cornea; position of globe (e.g., sunken in orbit or protruding); condition of eyelids, encrustation Posturee.g., hunched back, tucked abdomen; prostrate; head tucked down
37 Types of Observations Locomotion Neurological Vital Signs e.g., gait, ataxia, lameness, action of each limb, position of tail when ambulating Neurologicale.g., tremor, convulsion, circling, paralysis, head tilt, coma Vital Signse.g., respiratory distress (open mouth breathing, pronounced chest movement) Other clinical parameters that are relevant to your studye.g., presence and status of tumors, infection, or surgical woundsTip: It is helpful to have blank forms to use as "score sheets" to enter and track each parameter assessed.
38 Physical ExaminationAfter assessing the animals’ appearance and behavior, conduct a physical exam using methods that are appropriate to the species and experimental model.Performing a clinical exam on rodents is somewhat limited compared to larger animals due to the greater difficulty in venous access and the smaller sampling size of biological fluids. Nevertheless, specific methods and equipment for rodents allow a clinical exam to provide information on animal well being.Use quantifiable characteristics whenever possible. These can be tracked over time and compared to a starting baseline or to normal, untreated animals.Such measurements are not only helpful for clinical assessments, but they can also be useful when compiling research data and writing manuscripts. Later in this course, simple record-keeping methods will be discussed to help utilize this information.
39 Physical Examination You may evaluate: Behavior Body weight Surface lesions (wounds, masses)Hydration statusBody temperature (telemetric methods)Blood parameters (Blood collection can be difficult/stressful in mice; may be used to confirm disease or failed treatment.)For specific recommendations on evaluating these parameters and supportive procedures, refer to the AALAS Learning Library course Post-Procedure Care of Mice and Rats in Research: Minimizing Pain and Distress.
40 Humane Endpoints Defining Procedure All of the federal laws, regulations, policies and guidelines applicable to animal research have a core requirement for the humane treatment of the animals involved in a study.Accordingly, your IACUC will have requirements for the proper care (peri-procedural care) of your animals prior to, during, and after a research procedure.What is a procedure? A procedure is any activity carried out on the animal, such as a behavioral observation, a venipuncture, or a surgery.
41 Humane Endpoints Defining Procedure (cont) This peri-procedural care requirement covers:properly preparing the animal to humanely undergo the procedure,supporting the animal’s physiological function during the procedure, andproviding additional supportive care to aid the animal in recovering from the procedure.
42 Humane Endpoints Responsibility for Care The investigator has the responsibility to see that staff working with the animals are properly trained to not only perform the procedure humanely but also to provide the necessary supportive care to the animals.When performing any procedure, such as a blood collection, you should think through the steps that are necessary to protect the animal’s welfare.For example, for blood collection, you should limit the volume taken acutely or chronically. And, with any venipuncture, you should be prepared to care for the animal in the event of trauma to the vein area or excess hemorrhage. Refer to your institution’s IACUC and attending veterinarian for specific guidelines.
43 AcclimationUpon arrival to your facility, your mice should have an acclimation period before they are used in research studies.This period of time allows animals to adapt to a new environment.Effects of transportation stress include alterations in various blood parameters, immune cell function, food intake, and animal behavior.The period of time necessary for biological stabilization will depend on the parameters to be studied.Refer to your institution's attending veterinarian for recommendations that are appropriate for your project. Typically, acclimation periods can range from days to over a week, depending on the studies involved.
Your consent to our cookies if you continue to use this website.