This document defines animal models and discusses their use in research. It defines an animal model as a living organism that resembles a pathological process in humans. Major advances involving animal models are described from the 1600s to present day, including vaccination and understanding of infectious disease. Common animal models used are then outlined, including rodents like rats, mice and guinea pigs as well as non-rodents like rabbits, monkeys, cats and dogs. The document discusses specific uses and characteristics of different animal models and alternatives to animal testing.

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2. DEFINITION
• Weggler in 1983 defined an animal model as a living organism with an
inherited, naturally acquired, or induced pathological process that in
one or more respects closely resembles the same phenomenon in men.
• The institute of laboratory animal resources(ILAR) of the National
Academy of Sciences adopted and modified Weggler’s definition as
follows:
An animal model is a living organism in which normative biology or behavior can
be studied, or in which a spontaneous or induced pathological process can be
investigated, and in which the phenomenon in one or more respects resembles the
same phenomenon in humans or other species of animal.
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3. MAJOR ADVANCES IN RESEARCHES
THAT INVOLVED ANIMAL MODALS
1600's - Function of the lungs, Measurement of blood pressure.
1800's – Vaccination, Understanding of infectious diseases
1900's - Antibodies, hormones
1930's - Mechanism of nerve impulses, tumor viruses.
1940's - Embryonic development
1960's - Monoclonal antibodies, liver functions
1970's - Transplantation antigens, brain functions, Discovery of prostaglandins
1980's - Development of transgenic animals
1990's - Understanding auto-immune disorders, In vitro fertilization, cloning
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4. ANIMALS USED IN RESEARCH
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RODENT ANIMAL MODEL:
Rat
Mice
Guinea pigs
Hamster
NON – RODENT ANIMAL
MODELS:
Rabbit
Monkey
Cat
Dog
TRANSGENIC ANIMALS

5. RODENT ANIMAL MODEL
RAT(Rattus norvegicus)
Rats have been useful for research in the
following fields-
• Study of analgesics and anticonvulsants.
•Study of oestrus cycle, mating behavior and
lactation.
•Gastric acid secretion
•Hepatotoxicity studies
•Study on mast cells
•Bioassay of various hormones, such as insulin,
oxytocin, vasopressin .
• Rats are better at removing toxins from their
bodies than humans, so it may be possible to
refine the use of rats in toxicology studies.
•Rat brain tissue is extensively employed in
radio-receptor ligand studies.
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6. MICE(Mus musculus)
• They are most widely used in clinical
research as they are small, inexpensive
and easy to handle .
• Mice are used in a vast range of
experiments, many of which are classified
as fundamental research, investigating the
physiology of mammals.
•They have similar reproductive and nervous
systems to humans, and suffer from same
diseases such as cancer, diabetes and even
anxiety
•Their short life span and fast reproductive
rate, makes it possible to investigate
biological processes at all stages of the life
cycle.
• Swiss albino mice are the most commonly
used.
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7. EXPERIMENTAL USES
• Toxicological studies
• Teratogenicity studies
• Bioassay of insulin, screening of analgesic
and anticonvulsant drugs
• Screening of chemotherapeutic agents
• Studies related to genetics and cancer
research
• Drug action on CNS
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8. DIFFERENCE BETWEEN RATS
AND MICE
•The rat is much larger in size and has greater body
wieght as compared to the mouse.
•The mouse has a pointed face when compared to the
rat.
•The rat has a thick and heavy tail. On the other hand, a
mouse has a very thin tail
•The rat has a higher pair of chromosomes, ie 22 pairs.
On the contrary, the mouse has only a 20 pairs.
•The rats have a longer gestation period compared with
the mice.
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9. GUINEA PIG(Cavia porcellus)
• Guinea pigs have biological similarities to
humans, which make them useful in many
fields of research.
•Vitamin C was discovered through
research on guinea pigs.
•Their serum contains enzyme Aspariginase
which shows anti-leukaemic action.
They were also crucial to the development
of :
•Vaccines for diphtheria, TB,etc
•Evaluation of local anaesthetics,Antibiotics,
Histamine and antihistamines
,Anticoagulants ,Bronchodilators ,Bioassay
of Digitalis.
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10. NON – RODENT ANIMAL MODELS
RABBIT(Oryctolagus cuniculus)
•Historically, Louis Pasteur used rabbits
to develop the rabies vaccine.
•Studies in rabbits are key to many
aspects of medical research, including
cancer, glaucoma, eye and ear
infections, skin conditions, diabetes
and emphysema.
•The rabbit has been important in the
study of cardiovascular diseases ,
particularly hypertension and
atherosclerosis.
•Enzyme atropine esterase is present in
rabbit liver and plasma so it can
tolerate large doses of belladona
(atropine).
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11. RABBITS HAVE BEEN USED FOR RESEARCH IN FOLLOWING FIELDS :
• Pyrogen testing
• Bioassay of anti-diabetic drugs
• Screening of agents affecting capillary permeability
• Drugs used in glaucoma
• Studies related to anti-fertility agents
• It has simple cardiac tissue free of connective tissue and hence is the
animal of choice for cardiac studies.
•The rabbit has provided an excellent model system to simulate the
response of human tissue to the radiation produced by surgical
lasers.
• Laser advancements made possible by research on rabbits include
eye surgery and the dissolving of plaque build-up on the walls of
arteries.
TESTING OF COSMETICS USING DRAIZE TEST :
Rabbits - particularly albino rabbits - are commonly used in testing for
cosmetics and other chemicals, where they are used to perform the
Draize test. This test involves the substance being placed on the
rabbit's eyes or skin, which are then observed for redness, irritation or
any other damage.
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12. MONKEY(Macaca mulatta)
Used as primate model to
study drug metabolism .
•Suitable for undertaking
psycho-pharmacological
studies.
•Uterus resembles that of
humans, showing
regular menstrual
cycles.
•Best for studying drugs
acting on CNS, CVS,
GIT and fertility.
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13. DOG(Canis familiaris)
•Most preferred large
experimental animal due to
small alimentary tract and ease
of training.
•Used for studying various anti-
arrythmic, cardiovascular drugs.
•Mongrel and Beagles are the
most preferred due to
manageable size, moderate hair
coat and docile nature .
• Good model for Diabetes
Mellitus, Ulcerative Colitis,
Open heart surgery and organ
transplantation.
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14. CREATING TRANSGENIC
MODELS
•Zebra fish mutants are currently used to model many human
diseases, including Alzheimer’s disease, congenital heart
disease, polycystic kidney disease , cancers and development
of the nervous system.
•Its aim is to use the zebra fish to produce new disease models,
find new drug targets and learn more about the gene-
regulation pathways involved in human development and
disease.
•Using genetic techniques, a team of researchers stimulated the
development of a type of leukaemia - T cell acute
lymphoblastic leukaemia - in the fish.
•Creating zebra fish which develop leukaemia will enable
researchers to test the effect of various anti-cancer agents.
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15. ALTERNATIVE APPROACHES TO ANIMAL
TESTING
• Russel and burch in 1959 proposed that “if animals
were to be used in experiments, every effort should
be made to replace them with non-sentient
alternatives”
• They developed the 3R strategy which includes
– Refinement- refine experimental methods to decrease
unnecessary pain and trauma to animals
– Reduction- reduce the number of animals used in these
experiments
– Replacement- replace the animal experiments eg-
computer simulation models, In-vitro methods, cell
culture techniques
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16. METHODS OF REFINEMENT
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Setting the earliest possible end point
Using appropriate analgesics and anaesthetics for painful
procedure
Use proper handling technique for animals
Adequate training prior to performing experiment
Ensure drug doses are correct and drugs are not
expired
Perform surgeries and procedure aseptically to prevent infection

17. METHODS OF REDUCTION
• Perform pilot studies
• Design studies to use animals as their own
controls eg- Cross over study
• Gather data for more than one experiment
concurrently
• Consult with statistician and use minimum
number of animals
• Minimise variables such as disease, diet,
stress, genetics
• Use appropriate species of animals
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18. METHODS OF
REPLACEMENT
• Substitution of insentient material in place of
conscious higher animals
• Could be relative or absolute
• Replace higher animals with lower animals
• Replace live animals with dummies for
teaching and dissection purpose
• Use computer simulation and in vitro
methods
• Use cell culture and tissue culture
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19. REFERENCE
• A Review on Alternatives to Animal Testing
Methods in Drug Development. Ranganatha N,
I. J. Kuppast. International Journal of
Pharmacy and Pharmaceutical Sciences.
• www.aboutanimaltesting.co.uk
• www.animalresearch.info
• Images: Google images
• https://en.wikipedia.org/wiki/Model_organism
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