Transcript Rabbits - Yola - Kristin Singer

Rabbit
Oryctolagus cuniculus
Biology and Uses in Research
TAXONOMY
Class
 Order
 Family
 Genus
 Species

Mammalia
Lagamorpha
Leporidae
Oryctolagus
cuninulus
Lagomorphs are distinguished from rodents
by their incisor teeth.
Teeth

Lagomorphs have six
incisor teeth,
including the small
teeth (frequently
called peg teeth)
directly behind the
large upper incisors.
By contrast, rodents
have only four
incisors.
General Information
Known as the domestic rabbit
Derived from European wild rabbit
Used as pets, meat producers or research
Oryctolagus cuniculus is the only genus of the
European rabbit
Hares (lepus) and Cottontails (Sylvilagus) are in a
different genera
Fertile cross-genera mating do occur but offspring
are infertile
Breeds and Varieties
Over 40 different breeds/varieties
recognized by the American Rabbit
Breeder Assn
 Only a few used in meat production and
labs
 Many bred just for show quality
 Most have definite molting period

Breeds
Of the six genus in the Subfamily
Leporinae, only the European rabbit,
Oryctolagus cuniculus is commonly used in
research, testing, or teaching.
 Three of the most commonly used breeds
are the New Zealand White, American
Dutch, and Californian.

New Zealand White
Most commonly used
 White
 Most popular
 Used for food and
laboratory
 Mature weight 10
lbs/4.5 kgs
 Docile

American Dutch
The American Dutch
rabbit, is less than half
the size of the New
Zealand White, reaching
a mature weight of only
two kilograms.
 There are several color
varieties of the American
Dutch breed, but the
most common is the
black and white
 Second most popular in
research

California Rabbit
Primarily for food
 White fur with
dark brown tips
on feet, ears,
nose and tail
 Pigmentation
thermolabile
 Mature weight 10
lbs/4.5 kg

Chinchilla rabbit
Mature weight 10 lbs/4.5 kgs
 Steel grey

Flemish Giant
Checkered giant
Largest breed
Weight – 13 lbs
Not commonly used – too big
Mature slowly
Angora
Used for fur
Fur is plucked every 3 months
2 – 2 1/2 inches
Netherland Dwarf
Smallest
Weight – 2-3 lbs
Lop Eared
Medium size
Weight – 5-6 lbs
Lop ears
Hair growth patterns
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The hair growth patterns of
the rabbit are somewhat
unusual. After the rabbit's
hair has been clipped, it
may not grow back
uniformly.
Notice in this rabbit that
some patches of hair are
longer than others. This
can make interpretation of
some skin tests difficult.
Skeletal mass
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Only about 7% of the body
weight of a rabbit is skeletal
structure.
Compare the bone density of
a cat (on the top) with the
rabbit of approximately the
same weight (on the bottom).
This is a lateral view
radiograph.
The muscle mass of a rabbit
relative to bone structure
makes it highly susceptible to
lumbar fracture or dislocation.
Dental Formula
2x (2/1 I, 0/0 C, 3/3 P, 3/2 M) = 28
 Teeth grown and wear continuously
Vital signs
Normal vital signs will vary with the age
and breed of the rabbit, but for a healthy
animal they should fall within these
ranges:
 heart rate 130 - 325
 respiratory rate 32 -60
 rectal temp 101.3° F – 104° F
Urine


A healthy rabbit will produce about 50-75 mL of urine
per kilogram of body weight each day. It will normally
be dark yellow to brown and will appear turbid. This
turbidity is due to mineral precipitates. Rabbit urine is
normally alkaline with a pH of over 8.2
The urine forms scale (a thick mineral coating) on cages
as it dries.
Feces

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Healthy rabbits produce
two types of feces.
The droppings seen in the
pan under the cage are
hard fecal pellets that
contain mostly waste
fiber.
The other type is a softer
feces that is produced in
the cecum, and is often
called cecotrophs or night
feces. This material is
rich in vitamins and
protein, and the rabbit
may consume it directly
from the anus
Ear
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An important feature of
rabbits is the prominent
blood vessels in their
ears.
Rabbit ears are NOT
handles and must never
be used for restraint!
The central artery is used
for collecting large
quantities of blood. The
marginal ear vein is used
for giving IV injections or
collecting smaller
quantities of blood
Hematology
The blood volume of a rabbit is
approximately 56 ml/kg body weight.
 Generally, 10 - 15% of the total volume
can be taken as frequently as every two
weeks without endangering the rabbit.

Hematology
The normal range for the red blood cell count is
4.5 - 7.0 x 103. The total white blood cell
count and differential fall within the range
expected of most other species of laboratory
animals, as shown here:
Total WBC 4.6 - 13 X 103
Lymphocytes 30 - 50%
Neutrophils 30 - 50%
Monocytes 0 - 3%
Eosinophils 0 - 2%
Basophils 0- 7% (Ref Kozma, et al.).
Neutrophil, eosinophil


The rabbit neutrophil,
shown on the left,
contains granules that
stain red with eosin.
Because of this staining
characteristic, rabbit
neutrophils are
sometimes called
pseudoeosinophils,
amphophils, or
heterophils.
Let's look at a dissection of a rabbit to study the internal
organs that are most commonly relevant to research uses

This is a sagittal section of
the head showing the long
oropharynx (red pin), large
fleshy tongue, and the
sagittal niches. It also
shows the relationship of
the esophagus (yellow pin),
to the trachea (blue pin),
epiglottis (below the red
pin), and nasopharynx
(white pin). All of these
features combine to make
passing an endotracheal
tube difficult
Thoracic cavity

Dissection into the
thoracic cavity, shows
the heart, which is
relatively small for the
size of the animal -about 1/2 that of a cat
of the same size. This
becomes important
when attempting to
collect blood via cardiac
puncture.
Lungs
The lungs differ from
each other in size and
construction. The
right lung is normally
larger, and it has
three distinct lobes,
whereas the left has
only two.
 This image shows the
bilobed left lung

Abdominal cavity
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The abdominal cavity is
proportionately large,
reflecting the high
roughage content of the
diet. The liver lies
above the stomach.
The gall bladder is
buried deep in the liver,
and cannot be seen on
this image.
The cecum is very large,
and has about ten times
the capacity of the
stomach...
Stomach

...which is large, thinwalled, not
compartmentalized,
and relatively
aglandular. The pH in
an adult rabbit stomach
is very acid
Female reproductive organs
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This image shows the
female reproductive
organs -- the ovaries,
uterine horns, and
vagina which has been
cut open longitudinally.
The uterine horns are
separated their entire
length. Each horn
empties into a separate
cervix and then into the
vagina.
Placenta

The placental barrier in the rabbit is
hemochorial, which means that the
membrane enclosing the fetus is in direct
contact with maternal blood. This means
it is similar to the human barrier, making
the rabbit a good model for studying
transmission of agents through the
placenta.
Reproduction
The female rabbit is called a doe; she is generally larger
than the male. Females have four pairs of mammary
glands and often has a pronounced dewlap (roll of fur
under her chin).
 Male rabbits are called bucks. Bucks have no mammary
tissue and their inguinal canals are open. Group housed
bucks may fight.
 The rabbit is an induced ovulator and has no distinct
estrous cycle, although she is typically a spring
breeder. The doe ovulates ten to twelve hours after
mating. When she is receptive to a male, she exhibits a
posture called lordosis, elevating her hindquarters.
 Gestation in rabbits is 29 - 35 days. Parturition
( kindling) occurs in the early morning in a nest that the
doe makes by plucking fur from her dewlap, abdomen
and sides.

Sexing

Differentiating mature males from females is fairly easy.
As females mature, they develop a soft fold of skin
below their chin, from which they pluck hair when
nesting. This is called a dewlap. Compare the profile
of the female, left, with the male at the right.
Sexing

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To determine sex by
genitalia, gently press
the skin back from the
genital opening and
stretch the perineum.
In the male, this
procedure will cause
the penis to be everted.
The vulva of the female
has the appearance of
a slit. This procedure
is necessary when
sexing young rabbits.
Use in research
History of the Rabbit in Research:
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Rabbits were discovered in Spain in approximately 100
BC. They were transported throughout the Roman
Empire as an easily portable food source.
Domestication of the rabbit probably occurred when
French monks set up walled compounds during the
1500s.
Rabbits have been used in research for hundreds of
years. In the early 1600s, rabbit eyes were studied and
glaucoma was described.
In the 1880s, Louis Pasteur did much of his research and
testing of rabies vaccine using rabbits.
List of historical uses

The cause and treatment of many human
diseases have been studied using the rabbit as a
model. Because of its response to different diets,
the rabbit was the first animal model used to
study atherosclerosis. Other noninfectious
diseases studied in the rabbit include
osteoarthritis, pregnancy toxemia, endometrial
adenocarcinoma, drug teratogenesis,
hydrocephalus, muscular dystrophy,
glomerulonephritis, and gallstones.
List (cont.)

Infectious diseases studied in the rabbit
include staphylococcal infection, bacterial
endocarditis, and Reiter's polyarthritis
syndrome. Hereditary studies include
familial hypercholesterolemia, dwarfism,
and glaucoma.
Syphilis
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There are some diseases of
man for which only the rabbit
can serve as a model. One of
these is syphilis. The rabbit is
the only other mammal in
which syphilis occurs naturally.
The causative agent of human
syphilis, Treponema pallidium,
cannot be grown in vitro.
But we can put the human
organism into rabbits and study
its growth there. If and when a
vaccine is developed for human
syphilis, trials will undoubtedly
be conducted using the rabbit
first.
Pet vaccination

Animals have also
benefited from research
using rabbits. Pasteur
developed a vaccine to
protect dogs from rabies
by using dried spinal cord
from rabbits that had
been experimentally
infected
Analogous systems
Four other characteristics of rabbits make
them desirable for specific research tasks.
 First, by analogous systems, we mean that
some of the rabbit's organ systems are
very similar to systems in man.
 The rabbit is often the model of choice to
study immune responses for this reason.

Size

Rabbits may be preferred
over other common
laboratory animals because
of their size. They have
sufficient blood volume to
allow for large blood
samples to be taken either
singly or serially. Because
of their size, they may be
preferred over rodents for
studies that require
temperature monitoring or
surgical procedures.
Reasons Not to Use
Size
 Expense
 Variable response to anesthetic agents
 Prone to cardiovascular failure
 Prone to stress related diseases (excoccidiosis)

Reproduction study

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A doe has two uteri, each
of which opens into the
vagina through a
separate cervix. This
unique reproductive
anatomy allows for an
experimental group and a
control group within a
single biologic host.
Rabbits are also useful for
studies that require
precise timing during
gestation, as a doe
ovulates about ten hours
after mating, and
gestation is well defined
at 30-32 days.
Susceptibility to disease

The last of these characteristics that make
the rabbit valuable for specialized studies
is its susceptibility to spontaneous and
induced diseases; such as syphilis,
herpetic conjunctivitis, tumors associated
with papilloma viruses, glaucoma,
hyperlipidemia, and nutritional muscular
dystrophy.