Rabbit Anatomy -Rabbit Body Systems
~ Rabbit Anatomy
This page details the anatomy and various systems of a rabbit in a clear
step-by-step way. I'm going to try not to over-complicate things but
the learning experience interesting, effective and hopefully fun.
In the past I have studied, at great length, the anatomy of humans
and our internal systems, especially the wonders of our skin, so I will
sometimes use comparisons to create effective visualization and
understanding.I would like you to come away from this page with
an increased appreciation of the rabbit in general, a greater respect
for their life and a full comprehension of their fundamental rights to be the amazing creatures they
Rabbit Anatomy - Body Areas
Rabbit Anatomy - Systems
The anatomy of a rabbit can be as complex or as simple as you want it to be but for the purposes of an 'easier' appreciation and application in the all important areas, I will outline the following main systems of a rabbit's anatomy:                                  
Introduction to Rabbit Anatomy
First of all, you may be wondering 'Why do I need to understand a rabbit's body?'I
drive a modern car and the gadgets, computers and systems whirring and
jigging within it are a complete mystery to me. However, when it stops
working or doesn't do something it's supposed to, I am dumb-founded as
to know why. That's when I wish I'd taken a lesson or two in car
mechanics. Knowledge would have gone a long way to lowering the cost of
my garage bills too.
So, with that concept in mind, the information on this page will give you most of the necessary information to get your pet rabbit up and moving again, if they are not functioning the way they should, but more importantly, you will be able to prevent any further 'breakdowns' in the future!Of course a rabbit is a living being, not a machine. Your rabbit is your companion, your friend, your comfort and you probably regard them as part of your family. The knowledge you gain here will keep them with you, happy and healthy.Understanding how a rabbit's body works and the systems within it, will not only afford you greater respect for rabbits, but it will greatly aid your efforts as a rabbit owner, ensuring the health, happiness and increased life span of your beloved pet.Knowing how a rabbit's body works will help you understand the importance of such things as:correct dietexercise & freedomhabitatfriendships & socialization
Rabbit Anatomy - Skeletal System
The rabbit has a delicate skeleton compared with other mammals. It makes only 8% of the body weight,
as compared to 12 to
13% in cats. Here are some other important points to note about the rabbit skeletal system:There are 46 bones that make up the spinal column alone, 7 cervical (the neck), 12 thoracic (the chest), 7 lumbar (the lower back), 4 sacral (the pelvis) and 16 coccigeal (the tail).A rabbit's bones have extremely thin cortices and are easily
shattered.The lumbar vertebrae are elongated to allow for considerable flexion and extension during hopping, but this makes them susceptible to fracture.The powerful hind limb musculature
and light skeleton enable powerful jumping over long distances.The hopping movement is made possible due to the hind legs being longer than the fore legs. Most of the elongation is below the stifle (the knee) in two bones, the tibia and fibula. The tibia is also prone to fracture.Rabbit's hind legs can kick out with extreme force and if they struggle when they are picked up, or even when they stamp their feet violently on the ground, they are prone to fracture of their backbones (usually the 7th lumbar vertebra) and damage their spinal cord.Rabbits have 7 tarsal bones (the ankle) and 4 digits on both hind legs, and 9 carpal bones (the wrist) and 5 digits on both fore legs. Each digit has an associated toenail.
Weakened bones and bones affected
by osteoporosis are easily injured or broken.Various types
of spinal deformations have been observed in a rabbit's anatomy. The degree of
curvature is variable and may range from mild and barely visible to severe
and causing gait problems. The origin of these congenital deformations is not
well understood, they include:
hemivertebrae - abnormal birth defect in which the vertebra fails to
develop completely. As a result of the growth defect of the spine, a
wedge-shaped vertebra develops, and neighboring vertebrae expand or tilt to
fit the deformityspondylosis - a condition of the spine marked by stiffness of a
vertebral jointkyphosis - humplike curvature of the spinelordosis - abnormal, increased degree of forward curvature of any
part of the spine)These conditions may relate to a number of factors, a lack of calcium in the food, improper
absorption of calcium in the intestine, lack of exercise, wrong posture due
to being kept in a small cage, or defective genes. Female rabbits appear more
frequently affected by these spinal abnormalities than males. It is linked to
their higher needs in calcium, especially during pregnancy and lactation.
A rabbit's bone structure and density is
often affected in rabbits that don't get enough exercise or they have a lack of calcium in their diets.The severity of the deformations is
directly related and dependent on CAGE SIZE and lack of exercise!
Rabbits suffering from weak muscles
and poorly mineralized bones and/or bone degeneration are at increased risk
of spine fracture when there is an inadequate support of the heavily muscled
hindquarters, walking on a slippery floor, or twisting of the lumbosacral junction when frightened or restrained.
Rabbit Anatomy - Muscular System
rabbits are very athletic animals that are built to move rapidly in order to
find food, water, find or fight mates, or flee predators over greater
distances to find a hiding place.This daily exercise strengthens the
locomotive muscles, fortifies the muscles in their heart and lungs and increases their
resistance against stress. Just like us, exercise is wonderful for fortifying muscle and bones,
it will stimulate blood circulation and the activity and functioning of
other organs including the digestive system.
vertebras of the spine
provide support for the back. If this is accompanied by poorly
developed transversospinalis spine muscles and trunk muscles, the
normal balance of the spinal structure and the biomechanics can be
which can lead to degenerative processes. Deformations
that will prevent the development of a good locomotric
activity. Intrinsic muscle imbalance leads to degenerative changes of the lumbar vertebrae, even changes to femoral head
have been observed in rabbits that lack exercise.The rabbit muscular system, like in any vertebrate, is controlled by the
nervous system, it's the basic concept of any muscular system. Muscles
are controlled through electrical signals between the body's
parts and the brain.
Rabbit Anatomy - Digestive System
As total herbivores, rabbits have an
extremely long digestive tract in order to process their food in the most efficient way.The whole of a rabbit anatomy has evolved to survive on a very poor diet, the digestive tract especially. A special feature of the process, known as caecotrophy, is a remarkable way the rabbit 'recycles' waste faecal matter in order to extract any nutrients that may have been missed on the first, second or even third time round in the digestion system. ().The whole digestive system of the rabbit is huge and may account for between 10-20 per cent of its total body weight. Let's follow the process through the rabbit's anatomy...StomachIn an adult rabbit the
total length of the alimentary canal is 4.5 to 5 m. After a short
oesophagus there is a simple stomach which stores about 60-80 g
of a rather pasty mixture of feedstuffs. Food eaten by the rabbit quickly reaches the stomach where it remains for a few
hours, and although in an acid environment it has little chemical change. Liver & PancreasTwo major glands secrete into the small intestine: the liver
and the pancreas. Bile from the liver contains bile salts and
many organic substances but no enzymes. Bile aids digestion
catalytically. The reverse is true of pancreatic juice which
contains a sizable quantity of digestive enzymes allowing the
breakdown of proteins (trypsin, chymotrypsin), starch (amylase)
and fats (lipase).Small IntestineIf the small intestine of a rabbit was laid out it would be more than 10 times the length of the rabbit.The contents of
the stomach are gradually 'injected' into the small
intestine in short bursts, by strong stomach contractions. The small intestine is about 3 m long and nearly 1
cm in diameter. The contents are liquid, especially in the upper
part. Normally there are small tracts, about 12 cm long, which
are empty. The small intestine ends at the base of the caecum.
This second storage area is about 40-45 cm long with an average
diameter of 3-4 cm. It contains 100-120 g of a uniform pasty mix
with a dry matter content of about 20 percent.As the
contents enter the small intestine they are diluted by the flow
of bile, the first intestinal secretions and finally the
pancreatic juice.
After enzymatic action from these last two secretions the
elements that can easily be broken down are freed and pass
through the intestinal wall to be carried by the blood to the
cells. Large IntestineThe large intestine is made up of the caecum and colon. The caecum is very large, (about 10 times the volume of the stomach, and about 40 per cent of the total volume of the gastrointestinal tract).The colon separates the large and small fibre particles. The large particles of indigestible fibre are moved straight through the colon to form the hard droppings. the smaller fibre particles and other small incomplete digested food particles are moved backwards (by special muscles in the colon called haustrae). This 'slurry' enters the caecum where it is broken down and fermented.CaecumThe particles that are not broken down in the small intestine enter the caecum after less than 2 hours.
There they have to stay for about 2 to 12 hours,
while they are attacked by bacterial enzymes. Elements which can
be broken down by this new attack (mainly volatile fatty acids)
are freed and in turn pass through the wall of the digestive
tract and into the bloodstream.Very near the end of the small intestine, at the entrance to
the caecum, begins the exit to the colon. The caecum has a blind pouch branching off from the small intestine-colon
axis. Physiological studies show that this blind
pouch-reservoir forms part of the digestive tract: the contents
circulate from the base to the tip passing through the centre of
the caecum, then return towards the base, along the wall. The content of the caecum is then evacuated into the colon.
Approximately half consists of both large and small food
particles not already broken down, while the other half consists
of bacteria that have developed in the caecum, fed on matter from
the small intestine.
colon is about 1.5 m and follows on from the caecum, it is creased and dented
for about 50 cm (proximal colon) and smooth in the terminal
section (distal colon).The rabbit's digestive tract is
virtually the same as that of other monogastric animals, however in the rabbit anatomy, the digestive tract has a uniqueness that lies in the dual function of the proximal colon. If
the caecum content enters the colon in the early part of the
morning it undergoes few biochemical changes.If the caecal content enters the colon at another
time of day the reaction of the proximal colon is entirely
different.
Colon Dual ActionSuccessive waves of contractions in alternating directions
the first to evacuate the content normally and the
second to push it back into the caecum. The dual action of the colon produces
two types of excrement: soft and hard. Hard Pellets  (faecal droppings)These are round, relatively dry and composed mostly of undigested fibre. Normal faecal droppings are round balls, dark to light brown in colour,
and fairly inform in size. They are slightly moist when fresh but
dry out quickly. If you examine them closely, or break one apart (they
should crumble relatively easily), you will see the tiny rectangles
of undigested plant fibre that they are formed from.Droppings that are small, very dark in colour, or irregularly shaped
are a signal that your rabbit is not processing enough fibre through
his digestive tract. This may be because the diet is too low in fibre or
because another problem has slowed down the travel of food through
the digestive system.
If your rabbit stops producing any droppings, the gut may have
completely sto this should be treated as a
potentially
life threatening emergency and you should seek urgent veterinary
attention.Some rabbits eat their faecal pellets, this is normal as long as they are also eating the caecotrophes.Soft Pellets (caecotrophes)The colon wall
secretes a mucus which gradually envelops pellets formed by
the wall contractions. Under the varying
pressure and rhythm of contractions the content is squeezed
like a sponge. Most of the liquid part, containing soluble
products and small particles of less than 0.1 mm, is forced back
into the caecum.
These pellets gather in elongated clusters
and are called soft or night pellets (caecotrophes). The soft pellets are
recovered by the rabbit directly upon being expelled from the
anus. To do this the rabbit twists itself round, sucks in the
soft faeces as they emerge from the anus, then swallows without
chewing them. By the end of the morning there are large
numbers of these pellets inside the stomach, where they may
comprise three quarters of the total content.
From then on the soft pellets follow the same digestive
process as normal feed. Considering the fact that some parts of
the intake may be recycled once, twice and even three or four
times, and depending on the type of feed, the rabbit's digestive
process lasts from 18 to 30 hours in all, averaging 20 hours.
Half the soft pellets consist of imperfectly broken-down food
residues and what is left of the gastric secretions, and half of
bacteria. The latter contain an appreciable amount of high-value
proteins and watersoluble vitamins. The practice of caecotrophy
therefore has a certain nutritional value. The composition of the soft pellets and the quantity expelled
daily are relatively independent of the type of feed ingested,
since the bacteria remain constant.In particular, the amount of
dry matter recycled daily through caecotrophy is independent of
the fibre content of the feed. The higher the crude
content of the feed and/or the coarser the particles, the sooner
it passes through the digestive tract.
Digestible & Indigestible FibreThe dual action of the colon requires fibre but if the feed contains few large particles and/or it is highly
digestible, most of the caecal content is pushed back to the
caecum and loses elements which nourish the 'normal'
bacteria living in the caecum. This would appear to increase the
risk of undesirable bacteria developing in this impoverished
environment, some of which might be harmful.
Therefore it is advisable to minimize roughage in the
feed, enabling the rabbit's digestive process to be completed
fairly rapidly. In theory, roughage is provided by the crude
fibre content of the feed, as this is normally rather hard to
digest. However, certain fibre sources (beetroot pulp, fruit pulp
in general) are highly digestible (digestibility of crude fibre
varies from 60 to 80 percent). For this reason recommendations
are now made on quantities of indigestible crude fibre to be fed.(See , for more on this).
Adrenalin EffectsThe
digestive process of the rabbit appears to be highly dependent on
adrenalin secretions. Hypersecretion associated with stress slows
down digestive activity, and entails a high risk of digestive
ailments.Stress can be brought about by a number of factors, some that you may not even have considered. For example, a simple change in brand of food pellets can stress your rabbit, (), also children chasing them to try and pick them up can also cause an upset to their eating habits, ().
Rabbit Anatomy - Respiratory System
Rabbits are nasal breathers. Blocking their nasal passages for any reason, including oral examinations,
can lead to respiratory compromise due to the ineffectiveness
of mouth breathing. If a rabbit is breathing through its mouth, it is in severe respiratory distress.The rabbit has a small chest cavity compared with the size and weight of its digestive system. It should never be held in such a way that the abdominal contents press on the chest, as the rabbit will find it difficult to breathe.Rapid breathing may sometimes be a symptom of pain elsewhere in the body, and is seen in rabbits with bladder stones or womb cancer.
The nasal passages are in close
proximity with the maxillary dental arcade, and changes in either the
nasal passages or molar
tooth roots may affect each other adversely. ().Diseases invading
the nasal passages may alter bone structure, and may ultimately
lead to molar tooth movem conversely,
molar abnormalities and root elongation may impinge on nasal passages
and compromise respiration. .
The respiratory channel is separated
from the food channel by the presence of the palate. The respiratory system
of a rabbit comprises nasal chambers, larynx, trachea, bronchi and lungs.
Respiratory Organ & Related Parts:
Nasal chamber:The air passes through the external
nares into two large respiratory passages, which are hollow cavities
present above the plate. The respiratory passage is divided in to right
and left halves by the mesethm bone. Each side, the respiratory passages
is divided in to two regions.
An anterior nasal chamber.A posterior respiratory tube.
The nasal chamber is bounded dorsally by
nasal bone and ventrally by hard palate. The turbinals, very much
folded scroll kike bones, are present within the nasal chambers. The
turbinals are covered by richly vascular, glandular and ciliated
epithelium. One respiratory tube opens behind the soft palate through
the internal nares into the pharynx directly and that too very close to
the glottis.
The nasal chambers serve as very
efficient filters, i.e. it removes fine and coarse dust particles, germs
etc. through mucous covering the turbinals. It helps to warm up the air before it is to be inhaled and enters the lungs. Due to the covering of sensory epithelium, it also helps in the detection of smell.
LarynxThe pharynx opens into a larynx or sound
blood through the glottis. The larynx lends in to a trachea. This is
the anterior end of the windpipe or trachea.
The larynx is a cylindrical box like structure. Inside the larynx, there is a cavity
known as laryngeal chamber, which contains vocal cords. These vocal cords can be set into
vibration by the passage of air over them to produce the ‘voice’ – in
rabbits mainly a squeak.
TracheaAfter larynx, the trachea is a long
respiratory tube extending through the neck
into the thoracic cavity. It is lined internally by ciliated
cartilaginous rings. These ‘c’
shaped cartilaginous rings help to prevent the collapse of trachea and
to keep it expanded allowing free passage of air to and from the lungs.
The mucous glands present in the wall of trachea help keep its
inner surface moist and hold dust particles and
bacteria. Thus only the clear air is allowed to pass into the lungs. The
dust particles are swept towards the pharynx by cilia.The rabbit trachea is deeply
recessed within the oral cavity behind the torus of the tongue. The
trachea itself is narrow
relative to body size.
BronchiThe thoracic cavity is small in
comparison with the large abdominal cavity. Because of the small
cavity, rabbits have more referred upper airway and bronchial
sounds and may sound somewhat harsh. In the thorax, the trachea divides into
left and right bronchi which enter the lungs. The
bronchi possess the similar structure as the trachea. After entering in
to the lungs, each bronchus divides into many thinner branches, called
bronchioles.
Which again divide into finer bronches
of less diameter known as respiratory bronchioles. Each respiratory
bronchiole divides again into many finer branches, called alveolar ducts
or infundibulum. The alveolar ducts end in small hollow air sacs, known
as alveolar sacs. Each alveolar sac is formed of many small thin walled
hollow alveoli or air cells.
The respiratory bronchiole alveolar
duct, alveolar sac and alveoli are devoid of cartilaginous rings but
their walls possess ciia. There is a network of capillaries of pulmonary
artery and pulmonary vein around each alveolus. This complicated
branching increases the total respiratory surface and allows the air to
penetrate into every portion of the lungs.
LungsThe lungs are soft compact and spongy
mass of tissues lying in the pleural cavity within the thorax. Each lung
is covered by a fold of coelomic epithelium, which is in contact with
the organ (visceral pleura). Each lung is divided into lobes. The right
lung has four lobes. But left lung has got two lobes.Breathing During SurgerySignificant respiratory
compromise may occur if a rabbit is placed in dorsal recumbency
for surgery when the stomach or cecum is greatly distended.
Positioning the patient on a tilt table or elevating the thorax
with towels or pillows can decrease the risk of respiratory
compromise at surgery.
Rabbit Anatomy - Cardiovascular System
Function of the Cardiovascular SystemBy circulating blood throughout the body, the cardiovascular system functions to supply the tissues with oxygen and nutrients,
while removing carbon dioxide and other metabolic wastes. As
oxygen-rich blood from the heart flows to the tissues of the body,
oxygen and other chemicals move out of the blood and into the fluid
surrounding the cells of the body's tissues. Waste products and carbon
dioxide move into the blood to be carried away. As blood circulates
through organs such as the liver and kidneys some of these waste
products are removed. Blood then returns to the lungs, receives a fresh dose of oxygen and gives off carbon
dioxide. Then the cycle repeats itself. This process of circulation is
necessary for continued life of the cells, tissues, and ultimately the
whole organism. Up and down the evolutionary ladder, there are different
forms of cardiovascular systems with different levels of efficiency,
but they all perform this same basic function.However the cardiovascular system of
rabbits is slightly unique. Both the right and left atrioventricular valves are
bicuspid in rabbits. The
heart is small relative to total body size, comprising only 0.3%
of the total body weight. Rabbits have the most muscular
pulmonary artery of any species, which contributes to their
predisposition for pulmonary hypertension. Other vessels in rabbits
are thin-walled, and prone to collapse and hematoma formation with
venipuncture. The external jugular vein provides the main
route for venous drainage from the head, as compared to the
internal jugular vein in most mammals. There is a lack of anastomoses
between the external and internal jugular veins. This is
clinically significant because ligation or thrombosis of the external
jugular vein can lead to temporary exophthalmos. Ligation of the
external carotid artery will cause ocular necrosis on that side.Let's take a closer look at the different areas:
The Heart:ChambersThe rabbit heart
is di the left side pumps the blood to the body,
and the right side pumps blood to the lungs.The left side is
more muscular than the right as it needs to generate enough pressure to
pump blood round the entire body of the rabbit.The right side
receives blood carrying carbon dioxide (waste product) and pumps it to
the lungs. This carbon dioxide is then expelled from the lungs as the
rabbit breathes out.In return, oxygen is transferred to the
bloodstream from the lungs. The oxygenated blood passes to the left
side of the heart where it is pumped to the body, leaving the heart
through a large vessel called the aorta.ValvesBetween
each chamber of the heart there are special valves which ensure that
the blood does not flow backwards between beats. The characteristic "lub-dub, lub-dub" heart sounds heard through a stethoscope are the result of vibrations caused by the closing of the respective valves.Electrical NodesThere are two
different electrical nodes, or groups of specialized cells, located in
the cardiac tissue. The first is the sinoatrial node (SA), commonly
called the pacemaker. The pacemaker is embedded in the wall of the right
atrium. This small patch of tissue experiences rhythmic excitation and
the impulse rapidly spreads throughout the atria, causing a muscular
contraction and the pumping of blood from the atria to the ventricles.
The other node, the atrioventricular (AV) node, relays the impulse of
the SA node to the ventricles. It delays the impulse to prevent the
ventricles from contracting at the same time as the atria, thus giving
them time to fill with blood. The cycle of contraction of the heart
muscle is called a heartbeat, the rate of which varies greatly between
organisms.The average heart rate of a rabbit is about 205 beats per minute. The normal range can vary from 123 to 304 beats per minute.
Which, if you compare to a human, at an average heart rate of 70 beats
per minute, you can see why a rabbit's heart can be easily affected by
change or stress.Heart failure can occur in a similar way to
those of man. Their arteries can become 'furred up', affecting the
function of the heart. Rabbits that are fed a high calcium diet
can develop calcification of the aorta. this results in a loss of
elasticity of the blood vessel wall and leads, ultimately, to heart
Vessels:A blood vessel is a hollow tube for
transporting blood.
There are three main types of blood vessels:
ArteriesCapillariesVeins
These main blood vessels function to transport blood through the
entire body and exchange oxygen and nutrients for carbon dioxide and
ArteriesThe arteries carry blood away from the heart, and
are under high pressure from the pumping of the heart. To maintain their
structure under this pressure, they have thick, elastic walls to allow
stretch and recoil. The large pulmonary
artery carries unoxygenated blood from the right ventricles to the
lung, where it gives off carbon dioxide and receives oxygen. The aorta
is the largest artery. It carries oxygenated blood from the left
ventricle to the body. The arteries branch and eventually lead to
capillary beds.
CapillariesThe capillaries make up a network of tiny vessels
with extremely thin, highly permeable walls. They are present in all of
the major tissues of the body and function in the exchange of gases,
nutrients, and fluids between the blood, body tissues, and alveoli of the lungs.VeinsAt the opposite side of the capillary beds, the capillaries merge to form veins,
which return the blood back to the heart. The veins are under much less
pressure than the arteries and therefore have much thinner walls. The
veins also contain one-way valves in order to prevent the blood from
flowing the wrong direction in the absence of pressure. The pulmonary
vein returns oxygenated blood from the lungs to the left atria. The vena
cava returns blood from the body to the right atria. The blood that is
returned to the heart is then recycled through the cardiovascular
Rabbit Anatomy - Urogenital System
The Female Rabbit Urogenital SystemIn a female rabbit the urogenital system consists mainly of the following:ovaryinfundibulumoviductutericervixvaginaurogenital sinusmammary gland
The Male Rabbit Urogenital SystemIn a male rabbit the urogenital system consists mainly of the following:scrotumtestesepididymisvas deferensurethraprostatebulbourethral glandspenis
For the general purposes of rabbit care, I'm just going to cover two basic functions of the urogenital system within the rabbit anatomy:The Reproductive Systemand theUrinary System
Reproductive System
Female Reproductive SystemThe
reproductive organ of the female rabbit is considered a little primitive. Indeed,
the split two-horned system is only observed in monotreme
egg lying mammals and in lagomorphs (pika, hare and
rabbit). The organ is held in place by a broad ligament that is anchored at 4
points under the vertebral column.
differentiation occurs during the embryonic phase, on the 16th day post
fertilization. The ovaries grow from an aggregate of cells that is lying near
the original testes. The development of the ovaries is accompanied by the
degeneration of the testes.
development of the ovules (female reproductive cell) starts around the 21st
day and continues till birth, around the 30th day. The first ova and follicles
start to develop only 13 days after birth.
The reproductive organ of the female
rabbit is duplex: the uterus is formed by two independent horns, split over
their whole length. Each horn possess its
own cervix. The ovaries, ellipsoid bodies that have a maximal length of 1-1.5
cm, are located at the end of the uterus, right under the kidneys. They are
hidden by the mesometrium (portion of the broad
ligament that separates and encloses the uterus) and fat.The vagina does not present any
particularities. This part of the reproductive tract is large, with the
urethra joining halfway, at the level of the vaginal vestibule. At the end of
the vagina, the glands of Bartholin and prepucial glands can be recognized.Female rabbits do not have an estrus
(heat) cycle with regular periods of heat (estrus), as do other small animals
like dogs or cats. In fact, adult female rabbits,
(does) are considered to be more or
less always in estrus and are induced ovulators, (or 'reflex ovulators'), which means that intercourse stimulates ovulation. Then after about 40 seconds of mating , the egg is emitted for fertilisation.A certain cycle does nevertheless exist. The presence of the oestrogen
hormone will influence the size and the colour of the vulva. Most female
rabbits are receptive to a male and prone to mate when their vulva is coloured
reddish/purple, and will refuse to mate when their vulva is pale and small.
However, this is no clear indication though, as some female rabbits will mate when
their vulva is pale and small.
To avoid problems related to mating, health (ovarian
adenocarcinoma, endometritis) or/and unwanted
litter, ovariohysterectomy is recommended, starting
at the age of 6 months. The breed of the rabbit must be taken into account,
before performing the operation.
Sexual MaturityThe age at which sexual maturity is
reached depends on the size and the breed: while small and middle sized
rabbits become adult between 4 and 6 months, it may take between 5 to 8
months for giant breeds. As a rule, it is considered that a rabbit is adult
and able to reproduce when it has reached 75 to 80% of its adult size.
Male Reproductive SystemThe reproductive tract of a male rabbit is similar to most
mammals. 
The testes of male rabbits are
located within hairless scrotal sacs which are located cranial to the
penis. Paired testes produce sperm,
which become fertile as they are
transported through the epididymis.  Passage through the entire
epididymis takes approximately 4-7 days, and the resulting spermatozoa
are stored in the tail of the
epididymis, or cauda region.  Upon sexual
excitement,
this sperm is transported through the ductus deferens to
the pelvic
urethra.  It is then mixed with fluids
from the accessory
sex glands, and ejaculated through the penis.  Most rabbits ejaculate a
volume between
0.5-1.5 ml of semen.
Differentiating males from females can be difficult,
as the anogenital distance is the same in males and females, however eversion of the cranial orifice will reveal either a circular
entrance to the penis or a slit entrance to the vagina.
Urinary System
Urinary Tract
The urinary tract of the rabbit is similar to that of other mammals.
The upper urinary tract is comprised of: the kidneys (one each on the
left and right side of the body) and the ureters (tubes
that connect the kidneys to the urinary bladder) The lower urinary tract
is comprised of: the urinary bladder (simple collection bag for urine) and the urethra (the tube connecting the bladder to the outside of the body and is the
pathway for urine to travel during urination)
Urine is formed as blood goes into the kidneys and is filtered of waste
Depending on the hydration status of the rabbit, urine is
diluted or concentrated as the kidneys allow more or less water into the
Once formed, urine travels through collecting ducts in the
kidney to the ureters. Via the ureters, urine flows to the urinary
bladder. When the rabbit is ready to urinate, the muscles of the bladder contract
and the sphincter at the exit hole relaxes and urine is expressed out
the bladder and through the urethra and to the outside of the body.
In males, the urethra travels through the penis and is a long tapering
In females, the urethra is short and wide and ends in the vagina.Urine ColourThe urine of rabbits may be orange or brownish red in color. This has been attributed to dietary
compounds, plant pigment, or stress. The colour production is
usually intermittent, but may be mistaken for hematuria. The
calcium excreted in the urine may lead to a chalky or cloudy
appearance to the urine, and calcium carbonate or calcium oxalate
crystals may routinely be present in normal urine.
Rabbit Anatomy - Dental System
The dental arrangement of rabbits also comes under the umbrella of rabbit anatomy and physiology of rabbits. This part of the rabbit anatomy has evolved for efficient chewing of their bulky, fibrous natural
diets. DietMonocotyledenous plants such as grasses contain large numbers of
phytoliths, highly abrasive silicate deposits which cause marked wear of
the teeth. Since grass plants are low to moderate sources of dietary
energy, large quantities must be eaten for animals to survive. The
combination of fibrous structure and their abrasive nature requires
prolonged chewing, promoting tooth wear. ()Continual GrowthLost tooth substance must be
replaced to maintain chewing efficiency, and in rabbits, this is possible because the permanent teeth
remaining in a life-long growth phase. These continuously growing teeth
do not form anatomical roots, so the unerupted part of the teeth are
like the “reserve crowns” of larger herbivores.All of a rabbit’s permanent teeth grow and erupt continuously.Two Sets of TeethRabbits are diphyodont, having two recognizable sets
of teeth. A set of small or deciduous teeth, which erupt in utero, are
replaced by a fuller set of larger teeth by about one month of age. The
deciduous dental formula is: 2 x
The deciduous incisors are often shed before or around the time of
birth, whilst the last of the deciduous premolars are replaced by
permanent teeth by Day 35.The adult rabbit dental formula is: 2 x
Lagomorphs (rabbits, hares, and pikas) all possess two sets of maxillary
incisor teeth:
large first incisors and smaller peg-like incisors
positioned directly behind to the first ones. Rabbits and rodents both lack
canine teeth. A long diastema or gap sits between the
incisors and premolars in both rabbits and rodents.Cheek TeethThe
mandibular cheek teeth of rabbits grow and erupt at approximately 3 to 4
mm per month. Maxillary teeth grow and erupt at a slightly slower rate.
This wear is dramatically faster than occurs in large grazing animal
such as the horse whose cheek teeth wear and erupt approximately 3 mm
per year.In rabbits the cheeks fold in
behind the incisors separating the front of the oral cavity from the
more caudal section, thereby permitting separate function of the
incisors and back teeth.
Premolars and molars are commonly referred to as “cheek teeth”
since they tend to have similar structures and work together as a
functional unit. The cheek teeth consist of three maxillary and two
mandibular premolar teeth on each side, with three molars in each jaw
They are aligned to form nearly straight dental arcades, with oral
surfaces of adjacent teeth contacting to create a continuous chewing
This chewing surface wears to create a serrated pattern due to the
folded structure of the teeth, parallel layers of enamel and dentine in
upper and lower teeth wearing at different rates as the jaws are moved
side to side during chewing. Adjacent teeth are kept in contact by the
converging arrangement of the teeth, those towards the extremities of
the arcades tending to move inwards.This creates problems when a tooth
is lost or extracted from the middle of an arcade, as the adjacent teeth
tip into the defect creating gaps and irregularities in the occlusal
surface. These gaps become packed with food leading to progressive
periodontal disease, and the occlusal surfaces no longer wear normally
promoting malocclusion. ()Since the teeth do not meet one on one,
extraction of opposing teeth will make matters worse not better.
Rabbit Anatomy - Sense Organs
Natural Senses & InstinctsThe pet rabbit may be domesticated now, but they never lose their natural senses that their wild ancestors perfected. If rabbits are let out in the wild, they would go back to their natural ways of living - if they're not eaten by a bird of prey or hungry fox! Rabbits are hard-wired to live in groups in
which they establish social hierarchies. ().
The main sensory organs in the rabbit anatomy consist of:the eyes - visionthe nose - smellthe ears - hearingThere is of course, touch and taste but I'm just going to outline the main three above for the purposes of explaining general rabbit anatomy.
A rabbit spends his days eating, sleeping and staying away from
creatures looking for a tasty lunch. For this reason, rabbits may not be
able to focus as well as people, but they can pick up any movement and
make a hasty retreat. A rabbit’s field of vision is immense. He has
large eyes that are located on the sides and upper part of the head,
enabling each eye to see more than one half of a circle. Together, they
can see in every direction. Therefore, a rabbit can see an approaching
predator and be on the lookout for an escape route simultaneously. The
rabbit visual system is designed–not for foraging and locomotion–but to
quickly and effectively detect approaching predators from almost any
direction. Because the eyes are placed high and to the sides of the
skull, it allows the rabbit to see nearly 360 degrees, as well as far
above their head. Rabbits tend to be farsighted, which explains why they
may be frightened by an airplane flying overhead (Thinking it is a
predator from the sky). Despite their large field of vision, rabbits
have reduced depth perception as well as a limited degree of close-up
vision. If you think about it, rabbits don’t need to know exactly what
is coming at them. Any sudden movement will elicit flight. Even though
their close-up vision is not the best, rabbit eyes are designed to see
moving objects far in the distance. This allows them to see a predator
approaching at a great distance, and gives them ample time to run away.
Most rabbits won’t hang around to fight. Intense light blinds a rabbit,
as he has restricted contraction of his pupils. Rabbits have limited
colour perception, although it is widely thought that they can
distinguish between red and green. Sunset is the optimal time of day for
a rabbit to see. Rabbits enjoy being petted, but remember it is important to move
slowly as they can’t see very well up close. Never approach a
rabbit from the back, as this is reminiscent of being attacked by a
The twitch of a rabbit’s nose is a very obvious characteristic, and very
important to its survival. Not only does it draw air in to fill its
lungs and breathe, in the same way as we do, but it also helps the
rabbit detect danger, and identify friends and potential mates.When we smell something, our nostrils expand, lifting upwards and
outwards. The same thing happens in rabbits, but is more obvious because
they are constantly sniffing the air, rather than just breathing it in.
Rabbits have over fifty million receptor cells in their nose, compared
to our meagre six million. These enable rabbits to detect predators well
before they may even see them.Rabbits, like many other animals, have two types of scent detection
cells in their nose. Olfactory sensory cells detect ordinary airborne
odours, while a specialized group, the Jacobson Organ, pick up heavy
moisture-borne molecules and pheromones. (Moist air carries more scent).
When rabbits breathe in, their split top lip parts and moistens the air
as it passes. This enhances any scent and helps the rabbit discover
more about the world around it – who is nearby, friend, foe or female
ready to be mated, or any food source. As rabbits communicate mainly
through scent, a good sniff of each other no doubt is a bit like a long chin-wag over coffee! The nasal membrane is very sensitive to perfumes, chemicals and dust,
and these agents can cause upper respiratory problems for the rabbit. The sense of smell in a rabbit is present at birth, allowing a
newborn to find his mother’s teat. Rabbits shift their noses up and down
when trying this is called 'nose blinking'.
Rabbits hear pretty much in our range but they also hear much higher pitched
sounds which include rodents, bats, bugs, some bird noises and lots of
mechanical or electrical sounds we can’t hear. Hearing is a the
most vital sense within the rabbit anatomy. The auditory system is
used to detect predators, as well as to help a rabbit perceive the area
around him. Acoustics also help to overcome the reduced visual abilities by
allowing the rabbit to navigate without difficulty. Sound waves bounce
off objects, allowing the rabbit to recognize the arrangement of his
surroundings. Most rabbits have large, erect ears. When alert, the ears
move forward and backward as they attempt to pinpoint the danger. They can move their ears
independently of each other to help them hear if danger is approaching.
It’s the rabbit’s own built-in radar system.When
the rabbit is relaxed, the ears lie along his back, but they are quite
responsive to noise. The slightest sound can be detected from very far
away. The shape of a rabbits ears
allow them to pick up sounds over 2 miles away. Rabbit ears are long so
it can be down low in the grass but leave its ears sticking up to hear
clearly. Lop-eared rabbits also have good hearing but do not do as well
in the wild as rabbits with erect ears. Ear position is important in
rabbit language, even in lop ear breeds–watch their ears carefully -
Altogether, using these hyper-senses the
rabbit can manage to escape predators and many times even avoid them
completely.
Sensory Super Heros
To learn more about the , please see rabbit diseases for full descriptions of symptoms and treatments.
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