Chapter 3 - Terrestrial Environment

Question 1

How do temperature, humidity, and concentrations of gases and particulate matter differ between the micro- and macroenvironment? Light?

Answer 1

Often higher in microenvironment, while light is lower.

Question 2

How SHOULD animals be housed?

Answer 2

SHOULD be housed within temp and humidity ranges appropriate for species, to which they can adapt with minimal stress and physiologic alteration.

Question 3

What is the thermoneutral zone? What is it bound by?

Answer 3

TNZ - ambient temperature range in which thermoregulation occurs without the need to increase metabolic heat production or activate evaporative heat loss mechanisms. Bounded by lower and upper critical temperatures.

Question 4

What is the TNZ of mice, rats, gerbils, rabbits, and dogs/cats?

Answer 4

Mice: 26-34C
Rats: 26-30C
Gerbils: 28-32C
Rabbits: 15-20C
Cats/Dogs: 20-25C

Question 5

Where SHOULD dry-bulb temperatures be set in animal housing rooms? Why? What SHOULD be provided?

Answer 5

Should be set below the animals’ lower critical temperature to avoid heat stress. Should provide adequate resources for thermoregulation.

Question 6

How does the LCT of newborns compare to adults?

Answer 6

LCT is higher in neonates.

Question 7

Where should temperatures be maintained in reference to the ranges provided in the Guide?

Answer 7

In the middle of the ranges with minimal fluctuation.

Question 8

What animals generally require a thermal gradient in their primary enclosures to meet basic physiological processes?

Answer 8

Poikilotherms and young birds

Question 9

Abnormally high and low humidity is associated with what in mice? In rats?

Answer 9

Increased preweaning mortality in mice, ringtail in rats.

Question 10

Elevated microenvironmental relative humidity in rodent isolators may impact what other cage parameter?

Answer 10

Can lead to high intracage ammonia concentrations

Question 11

What physical structures impact how the microenvironments are ventilated and SHOULD be considered?

Answer 11

Type and location of supply air diffusers and exhaust registers in regards to primary enclosures.

Question 12

What SHOULD be avoided in regards to air speed? This is particularly important for what animals?

Answer 12

Direct exposure to air moving at high velocity (drafts). Problematic for neonatal homeotherms, mutants lacking fur, and semiaquatic amphibians that can dessicate.

Question 13

Modern HVAC systems allow ventilation rates to be set in accordance with heat load and other variables, but SHOULD always provide what?

Answer 13

Should always provide a minimum amount of air exchange, as recommended for general use laboratories.

Question 14

If IVCs ventilate cages, why SHOULD the macroenvironment be ventilated? (4)

Answer 14

To address heat load, particulates, odors, and waste gases from primary enclosures

Question 15

How is air exhausted from microenvironments handled?

Answer 15

If adequate filtration to address contamination risk, can be exhausted to animal housing room. Generally preferable to exhaust directly into building’s exhaust to reduce heat load and macroenvironmental contamination.

Question 16

What is an advantage of recycled air? A risk? How SHOULD exhausted air be recycled? What SHOULD also be considered?

Answer 16

Saves energy but risks cross contamination. Should be filtered at minimum with 85-95% ASHRAE efficient filters to remove airborne particles. Also consider filtering volatile substances (ammonia).

Question 17

What SHOULD be addressed in areas that require filtration to ensure personnel and/or animal safety?

Answer 17

Filter integrity, efficiency, and loading.

Question 18

What HVAC parameters SHOULD be monitored?

Answer 18

Supply and exhaust air volumes, fluctuations in temp and relative humidity, and air pressure differentials between spaces

Question 19

What are three potential photostressors?

Answer 19

Inappropriate photoperiod, photointensity, and spectral quality of light.

Question 20

Intrinsically photosensitive retinal ganglion cells are important for what types of regulation? (3)

Answer 20

Neuroendocrine, circadian, and neurobehavioral

Question 21

In general, what SHOULD light provided to an animal holding room provide?

Answer 21

Should be diffused throughout an animal holding area and permit sufficient illumination for animal well-being while permitting good housekeeping practices, adequate animal inspection including for the bottom-most cage, and safe working conditions. SHOULD provide for adequate vision and neuroendocrine regulation of diurnal and circadian cycles.

Question 22

Photoperiod is a critical regulator of what?

Answer 22

Reproductive behavior

Question 23

Will chickens eat in the dark? Why is this important?

Answer 23

Will not eat in low light or darkness, so illumination cycles SHOULD be limited to a duration that will not compromise their well-being.

Question 24

What SHOULD be used to control the light cycle? How SHOULD this be maintained?

Answer 24

Should use a time-controlled lighting cycle to ensure a regular diurnal cycle, which should be checked regularly to ensure proper cycling.

Question 25

What light level at what distance above the floor is appropriate for animal care and does not cause clinical signs of phototoxic retinopathy in albino rats? Levels up to what lux are satisfactory for rodents if management practices are used to prevent retinal damage to albinos?

Answer 25

325 lux, 400 lux

Question 26

What lux above the light level an albino animal was raised at can near the threshold of retinal damage?

Answer 26

130-270 lux

Question 27

Some guidelines recommend a light intensity as low as what at the position of the animal midcage?

Answer 27

40 lux

Question 28

Albino rats prefer areas with a light intensity of what?

Answer 28

Less than 25 lux

Question 29

How does the light preference of adults and young differ?

Answer 29

Young prefer lower illumination

Question 30

Light should be maintained at what level for animals that have been shown to be susceptible to phototoxic retinopathy?

Answer 30

130-325 lux in room at cage level

Question 31

How does light intensity change with distance from the light source? How is this difference appreciated from the top to bottom of the rack or within a cage?

Answer 31

Decreases with the square of the distance from its source. As much as an 80-fold change from the top to the bottom of the rack, 20-fold difference within a cage.

Question 32

What management practices can reduce in appropriate light stimulation?

Answer 32

Rotating cage positions or providing animals ways to control their own light exposure by behavioral means.

Question 33

What can changes in daytime room illumination for maintenance purposes change?

Answer 33

Photoreceptor physiology and circadian regulation

Question 34

Which loud species SHOULD be hosed away from quieter animals?

Answer 34

Dogs, swine, goats, NHPs, and some birds should be housed away from rodents, rabbits, and cats.

Question 35

Exposure to sound greater than what level can have auditory and nonauditory effects. What are these? (4) What may be required?

Answer 35

85 dB. Eosinopenia, increased adrenal gland weight, reduced fertility in rodents, increased blood pressure in NHPs. Hearing protection for personnel may be required at 85 dB

Question 36

Rodents are sensitive to what sound that is inaudible to humans?

Answer 36

Ultrasound

Question 37

Where SHOULD noise-generating activities take place?

Answer 37

To the greatest extent possible, in rooms or areas separate from those used for housing

Question 38

SHOULD radios, alarms, and other sound generators be used in animal rooms? What SHOULD happen at the end of the day?

Answer 38

Only if part of an approved protocol or enrichment program. Should be switched off at the end of the working day to minimize associated adverse physiologic changes.

Question 39

Describe vibration in an animal facility.

Answer 39

Associated with biochemical and reproductive changes. May be located within or outside the animal facility. Attempts SHOULD be made to minimize the generation of vibration, including from humans, and excessive vibration SHOULD be avoided.