Test #1: Factors Affecting Animal Research Data Validity:

Variables that ARE Easily Recognized & Controlled:

• diet

• environmental temperature

• humidity

• ventilation

• light cycle

• water (potability/purity)

• noise

Variables that ARE NOT Easily Recognized & Controlled:

• animal genetics (strain purity)

• latent disease

• environmental contaminants

• microbial transmission

• subtle behavioral stressors

• idiosyncratic reactions

Environmental Factors: Humidity:

• Ideal: 40-70% RH

• appropriate humidity levels facilitate thermoregulation

• goal is maintenance of “thermoneutral zone”

Humidity Monitoring:

• central computer

• gauges

• sling psychrometer

• hygrothermograph

Low Humidity:

• occurs in winter when heating systems dry the air

• occurs in area where desert-like conditions exist

• leads to increased dust accumulation in the air, the room and in cages

• Low is <40% RH

• can cause “ringtail” in young rats

• rectify with humidifiers in HVAC system

• rectify individual room humidifiers

Problems Associated with Dust:

• bacterial and viral particles can adhere to dust

• air currents can disseminate the contaminated dust particles throughout the room

Mucociliary “Escalator”

• rhythmic/synchronized movement of cilia in air passages moves the overlying mucus layer and the inspired particulate matter up the trachea where it is expelled

• with low humidity, mucus layer dries up and cilia stop moving, allowing particulate matter ti accumulate deep within lungs, increasing chance of infection

High Humidity:

• occurs in rooms with auto flush rack pans

• occurs in cages with filtertops which are not frequently changed

• high- 70% RH

• reduces resistance to infection

• increases predisposition to heat stress when temperatures are above recommended levels

Temperature:

• affects animal body temp

• high or low body temps affect metabolism

• recommendations established for room temps, dont address microenvironmental temps inside cage

• Monitor by:

  • central computer system

  • gauges

  • hygrothermograph

  • room high/low thermometers

Microenvironmental Temp Factors:

• room temp and humidity

• cage design

• cage population

• activity of animals

• amount and velocity of ventilation at cage level

Below the Thermoneutrality Zone:

• Adaptations to Minimize Heat Loss:

  • peripheral vasoconstriction

  • increased metabolic activity

    • increased food consumption

    • variation in biological response

Above the Thermoneutrality Zone:

• Adaptations to Minimize Heat Acquisition:

  • peripheral vasodilation

  • decreased metabolic activity

  • decreased reproductive performance

  • decreased lactation

Temperature Control:

• daily monitoring and adjustments

• air conditioning/ heating system

• humidity control

• limiting cage populations

Ventilation:

• provides or removes heat as needed

• removes waste gases (carbon dioxide and ammonia)

• reduces dust and particulates air

• removes odors

• affected by cage design

Ventilation: Achieved With:

• HVAC systems (heating, ventilation, & air conditioning)

• individually ventilated cages / racks

• exhaust fans

• outdoor open-air facilities

Ventilation: Ideal Criteria:

• 10-15 (100%) air changes per hour

• reduce airborne particulate contamination

• reduce odors