Bun
Biology 101
 Rabbits belong to a family known as leporids (along with
hares). They are no longer classified as a rodent.
The domestic rabbit (Oryctolagus cuniculus) originated from
the European wild rabbit. There are many other species of
rabbit, and these, along with cottontails, pikas and hares
make up the Order Lagomorpha. The full taxonomy is:
Order: Lagamorpha
Family: Leporidae (rabbits and hares)
Genus: Lepus, hares
Genus: Cylvilagus, cottontail rabbit
Genus & Species: Oryctolagus cuniculus, European
or true rabbit
 Rabbits are gregarious animals that live in
burrows in open fields and along hedgerows. They are
nocturnal, coming out of the burrows in the evening and
retiring in the early morning. Grasses and other herbaceous
plants are foods of choice; the bark of woody plants are eaten
if herbaceous plants are not available. (Lousiana
Vet. Med. Assoc.)
Anatomy and Physiology (from
LVMA)
Adult body weight: NZW: 2 - 6 kg (female); 2 - 5
kg (male)
Life span: 5 - 6 years
Respiratory rate: 32 - 60 breaths/minute
Heart rate: 130 - 325 beats/minute
Normal average rectal temperature: 102.5ºF
- The dental formula is 2(I 2/1, C 0/0, P 3/2, M 3/3) =
28. All teeth are open rooted and grow continuously.
- The cecum is large, thin-walled, coiled, and
terminates in the thick-walled light-colored vermiform
process or cecal-appendix. This appendix contains a
large amount of lymphoid tissue. Just proximal to the
cecum is another gastrointestinal structure containing a
large amount of lymphoid tissue, the sacculus rotundus.
- The left lung consists of two lobes, the right lung
consists of four lobes.
- The right atrioventricular valve of the heart, called
the tricuspid valve in human, has two cusps.
- The rabbit possesses a well-developed nictitating
membrane, the third eyelid.
- The uterus is duplex with separate cervical and
uterine openings.
- There are usually four pairs of mammary glands.
- The bones are relatively lightweight and represent
only 8% of the body weight of the rabbit, compared to
13% in the cat. The rabbit has strong musculature.
- The highly vascularized ears are important in
thermoregulation.
- Rabbit neutrophils contain eosinophilic granules and
are termed heterophils. These heterophils may be
confused with eosinophils and are distinguished by their
cellular size and granule size (smaller than
eosinophils), and the intensity of the granule
staining (less intense than eosinophils). The
larger granules of eosinophils often obscure the
nucleus.
- The normal urine pH is 8.2. The urine of young rabbits
is free of precipitate but albuminuria is normal; the
urine of mature rabbits is cloudy due to the presence of
ammonium magnesium phosphate and calcium carbonate
crystals. The color may vary from tan to reddish-orange,
the latter color being due to the presence of porphyrin
and bilirubin derivatives. This reddish-orange color is
intensified during dehydration or by certain pigmented
or high calcium diets, and must be differentiated from
hematuria (blood in the urine).
Picture at upper left is courtesy of
Sluggy Freelance
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