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Chapter Eight Laboratory Animal Environment
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Environment, Equipment, & Hygiene Standards, equipment & procedures safety & potentially hazardous problems Animal facility commonly located in building or wing separated from labs & offices. Facility = animal rooms, cage wash, offices, locker rooms, storage, surgery suites & other rooms. Environment (temperature, humidity, noise & air exchange) evaluated for level & consistency. Animals outdoors need protection from heat, cold & other environmental extremes.
(Image) Animal Facility Corridor
Animal Rooms Conventional = no special precautions to prevent introduction of disease Feed, groom & vaccinate against diseases don’t keep in special room to isolate Larger animals in conventional cages & rooms Barrier = special cages & procedures practiced A barrier = cage, a room or even entire facility Temperature, humidity, ventilation, light, noise & other variables in room affect environment. Direct effect on behavior & health which impacts data. The Guide provides table of recommended temperature levels for common laboratory species.
Temperature & Humidity Too hot or too cold can induce stress in animals. In rodent breeding room, ~ 72°F suitable for neonates Newly-hatched chicks or hairless rodents, & post- operative recovery = warmer end of range. Newly-hatched chicks & very young pigs may require an extra heat source. Temp > 80°F, adult mice may suffer heat stress. Humidity = amount of moisture in air. Range of relative humidity is 30–70%. Low humidity = ringtail & respiratory problems. High humidity = respiratory problems & food spoilage.
Ventilation Ventilation helps eliminate noxious odors. ammonia = by-product of breakdown of urine The Guide: exchanges of fresh air/hour. Recirculated air filtered to remove contaminants. Room is under + or – pressure. + pressure rooms = > pressure than surroundings Opening a door causes air to flow out toward the hallway. Surgical suites, barrier rooms under + pressure. - pressure rooms = < pressure than surroundings Opening a door causes air to flow into the room. Quarantine and conditioning & rooms to contain hazardous agents under – pressure. Check air pressure regularly to be sure correct.
Lighting Lighting evenly distributed & bright enough Change = stress & affects breeding efficiency. Turn lights on or off at prescribed times. Check lights on automatic timers. Long exposure to bright light = problem for albino. Research may call for specific light/dark cycles. Natural light varies & interferes w/ controlled light. Some systems permit changing light intensity. Lower level used to maintain animals. Level temporarily increased for room cleaning & maintenance.
Noise Certain rodents, cats, guinea pigs & rabbits react negatively to noises. Rabbits may jump & injure self, rodents may not breed. Noise may alter hormone levels. Technicians should avoid making loud noises (shouting or banging cage doors). Radio may be played to provide low-level background noise, reduces startle response. Speech in comforting tones to noise-sensitive animals may calm them. House these animals away from noisy animals, activities & busy areas.
Animal Room Construction Ideal animal room allows easy cleaning. Non-slip, waterproof floors & drain covers prevent debris from going into sewer. Floors are sloped toward drains. Walls and ceilings made of sealed material waterproof & easy to clean surfaces free of cracks, chipped paint & vermin-proof moisture-proof & vermin-proof recessed fixtures & outlets Doors self-closing, with a view port, kick plate, locks & recessed handles. Dimensions are a minimum of 42 inches X 84 inches.
Barrier & Containment More sophisticated rooms Designed to prevent entry of disease or disease in- side room from getting out. Shower and wear special protective clothing. Cages, bedding, food & water sterilized before entering room to prevent introduction of disease. SPF = animals do not have certain diseases. Barrier rooms have standard design features, but they have a filtered air supply. Air passes through a HEPA filter to remove dust & particles from air.
Hallways and Traffic Patterns High traffic areas & require durable construction. Bumper guards on walls and corners help protect surfaces from becoming chipped and marred. Recommended hallway width of 6–8 feet. Double-door airlocks at end of hallways help reduce noise, odors & possible contamination. Doors that open inward prevent collisions. Fixtures recessed into wall facilitate equipment movement.
(Image) Animal Facility Hallway
Hallways and Traffic Patterns II Single hallway w/ all rooms off same hallway = clean & dirty cages through same area. In clean/dirty system animal room has 2 doors: 1 - entering from clean hallway 2 - leading into the dirty hallway Prevent dirty from contaminating clean Enter room from clean, exit by dirty hallway. Disinfect shipping boxes prior to entering facility. Disinfect or autoclave supplies before entering barrier. To work, staff must abide by design requirements.
Facility Security Vandalism & theft add to cost of research by destroying years of effort & wasting animal lives. Door locks, computerized card entry system After opening security doors, check that they have been relocked. Never give unauthorized people keys, access cards & door combinations Find out who stranger is by asking, “How may I help you?” Advise supervisors immediately of presence of unauthorized people.
Cage Washing Rooms Cage washing activities are noisy. Locate areas away from animal areas & offices. Ventilate areas well to remove steam & odors. Seal all electrical outlets, light fixtures, walls, floors & ceilings to allow proper cleaning. prevent water & moisture from penetrating
Quarantine, Conditioning & Isolation Quarantine area separates incoming animals from animals already in the facility. During quarantine, personnel perform health status evaluations & monitor for disease. While in quarantine area, animals adjust to new surroundings, referred to as conditioning. Can be constructed as specialized cubicles each cubicle equipped w/ negative-pressure air supply Isolation for animals known or suspected of carrying disease Isolation rooms operate on negative pressure air supply.
Feed and Bedding Storage Must be vermin-proof & dry Feed & bedding stored on shelves or pallets, away from walls. Cool temp and low humidity avoid spoilage. Separate storage areas designated for clean equipment. Do not store disinfectants & chemicals w/ clean equipment, feed or bedding. Hallways, corridors & animal rooms should not be used as storage areas. Items obstruct traffic flow, accumulate dirt and can be a safety hazard.
Personnel Areas: offices, lunch rooms, showers & locker rooms Lunch & office areas are only place in which eating & other break activities are permitted. Procedure rooms - investigators & technicians perform experimental or therapeutic procedures Performing procedures in animal room may alarm other animals. Contain examining tables for diagnostic or experimental work & some storage space. Personnel & Procedure Areas
Emergency Back-up Power Without ventilation, air conditioning or heat = no fresh air in the facility. Causes temperature and ammonia levels to rise Prolonged high levels of ammonia or carbon dioxide can have serious effects on animal health. Loss of negative air pressure is a serious problem in quarantine and containment areas.
Hazardous Agents Use of materials or procedures that present a physical, chemical, biological or radiological hazard Document potential problems & precautions before any research involving hazardous agents. Signs & notices of hazard type must be posted where hazardous agents are being used. Contaminated animals or wastes disposed of in areas bearing biohazard symbol. ALWAYS ASK FIRST & proceed only when confident proper procedures are being followed.
Radioisotope Hazards Radioisotopes emit low levels of radiation, which makes them valuable in studies of processes such as digestion. Radioisotopes are usually dangerous only if contacted directly; some require stringent precautions & safety measures. Radiation monitoring badge records exposure and is worn by staff working with radioisotopes. Institutions using radioactive materials must conform to federal NRC guidelines.
Pathogen Hazards Infectious bacteria, viruses, fungi or parasites that pose a threat to humans and animals Some can cause disease in humans and may be present in research animals that are not SPF. Pathogens are utilized for research studies. i.e. developing tuberculosis vaccine CDC publishes guidelines for handling organisms & infected animals. Guidelines outline biosafety levels depending on degree of danger to humans. Biosafety levels graded from 1 to 4. BSL 1 is least & BSL 4 most hazardous. Diagram of HIV virus
Mutagen, Carcinogens & Toxin Hazards Mutagens cause changes in chromosomes. Induce occurrence of mutations. Carcinogens can induce cancer directly. Dilute formaldehyde (formalin) tissue preservative. Toxins are poisonous substances. i.e. formaldehyde and gas anesthetics Toxins can also be produced by bacterial, plant or animal cells. Organism that causes tetanus produces a toxin which is responsible for symptoms.
Hazard Containment Following features help contain hazards: + and - air pressure differences Filtration of exhaust air Airlocks and pass-through autoclaves Ultraviolet light to destroy organisms on surfaces Change and shower rooms Intercom systems between areas Treatment of contaminated sewage Back-flow check valves in main water supply lines Separation between containment & utility systems SOP for each specific biohazard under study Covers proper use of PPE
Dead Animal Storage & Disposal Place in plastic bags & either freeze or refrigerate until destroyed or removed. Plastic or metal cans used for storing carcasses should be leak proof & have tight-fitting lids. Store only dead animals in these units Incineration is safe & sanitary means of disposal. If animal is found dead, notify supervisor who will notify veterinarian & PI. May perform necropsy & take certain tissues from animal before disposal. Clearly label carcass & place in refrigerator until a necropsy can be performed.
Caging - The Microenvironment Animals must be able to move freely & have access to clean food and water. SOPs describe housing standards & care. Adhering to space recommendations allows animals to have enough room to make normal postural adjustments. Too many animals or cages that are too small causes stress. affect physiology, behavior & research data Crowding is both inhumane & against the law. USDA’s AWA & The Guide provide specific guidelines.
(Image) Various Types of Caging
Bedding Bedding = an absorbent in waste collection pans & material in direct contact with animals. Cage design determines what type of bedding is used; direct or indirect bedding. Too muchToo littleJust right
Bedding II Characteristics of good bedding material are: No ideal material for all species in all applications. ground corn cob, wood shavings, compressed paper & straw All bedding products create a certain amount of dust & can clog spray jets in cage washers.
Additional Reading Biosafety in Microbiological and Biomedical Laboratories. HHS Publication No. (CDC) rd. Edition US Government Printing Office, Washington, D.C Guide for the Care and Use of Laboratory Animals. National Academy Press, 1996.