WELFARE & PROCEDURES IN EMPLOYING LAB ANIMALS IN RESEARCH

Experimental animals = animals used for experiments 

= animals bred & reared in lab for scientific experiments 

Experimental organisms = insects, single cell organisms, all types of living organisms 

Characteristics of a common lab animal: 

small (easily kept)

easy to handle & manipulate 

easy to breed 

available in large qty

short gestation period

小，易处理易繁育，数量多，孕期短 

Why use lab animals?

to study itself (physiology, behavior, anatomy)

- able to differentiate into species/breed

biomodels = use as model to study other species/ human

Classification: 

Species & microbiological status 

1. Axenic animals 

no microbe & parasite in/on body since born 

maintain in closed sterile chambers = isolators

无菌

2. Gnotobiotic animals 

Gnoto = known, bio = life

axenic animals inoculated with known org/s

maintain in isolators 

接种了已知生物

3. Specific Pathogen Free (SPF) animals

free of specific microbe/parasites

not necessary free of others 

无特定菌类

4. Conventional animals 

with unknown microflora status 

apparently healthy (looks healthy)

未知菌

Isolators

Animal model = a living org with an inherited, naturally acquired or induced pathological process that closely resembles the same phenomena in man 

Characteristics of a good animal model: 

accurately reproduces ds or lesions

widespread availability to investigators 

large enough for multiple biopsies

ease of handling

longevity 

可繁衍疾病，数量足，足够进行切割组织，易处理，长寿

Types of animal models: NO SIT

1. Induced model

stimulated pathological state 

ex: chemically induced diabetes by Alloxan or Streptozotoxin

surgical removal/alteration

ex: bile duct ligated rats, partial hepatectomy rats 

2. Spontaneous model

naturally occurring genetic variant similar to human 

ex: nude mice used to study immune system; spontaneous diabetes rats, Watanabe hyperlipidemic rabbits

3. Transgenic model

advancement in recombinant DNA tech

produced by inserting a foreign gene into an embryo 

ex: AIDS, hypertension, sickle cell anemia

4. Negative model

do not produce particular ds

ex: gonococcal infection in rabbit

always exhibit lack of responsiveness to the stimuli

useful for study of mechanism of resistance

5. Orphan model 

describe a condition occur naturally in a non-human species BUT not yet been identified in humans

ex: Marek’s Disease, Papillomatosis and Bovine Spongiform Encephalopathy

Avoid using animals 

Animal welfare 

Donald Broom 1996: Welfare of an individual is its state to cope with its environment

Welfare assessments:

1. Physiological measurements 

Increased heart rate 

Adrenal activity 

Reduced immunological response when challenge

2. Behavioral measurements:

Avoidance test (strongly avoid = poor welfare) 

Self-mutilating 

Positive preferences = good welfare

Measure the ability to carry out normal behavior or other biological functions: 

Hens flap their wings but in cages they can’t 

Reproductive functions 

Social behavior 

Level Competition in the group

Stress:

Broom & Johnson 1993: an environmental effect on an individual which overcomes the control of the individuals and reduces its fitness

Stress = poor welfare = failure to cope with environment

Consequences of stress: 4R1B

Reduced production 

Reduced growth rate 

Reduced fertility 

Reduced immunity 

Behavioral changes

Solutions reducing stress & improve welfare:

Environmental enrichment

1. Social enrichment

2. Non-social enrichment: 

structural modifications

exercise, play & exploration

allowing control

Lab animal housing solutions