Biology of the Rabbit
by François LEBAS
 Directeur de Recherches honoraire de l'INRA
English revised version of "Biologie du lapin" , translated from French by Cathy R. Martin and Joan M. Rosell
Edition 2020
                                                                                                                                  Les dernières modifications

2 - External view and Morphology

 

  The main parts of the rabbit's body.
      The main parts of the rabbit's body appear in figure 1. In most breeds, except for the dwarf ones, the general appearance differs according to sex. A long, robust head, fully-developed thorax, relatively stout limbs and well-defined musculature are usually characteristic of the male. In the same proportion, the female is generally heavier (+5% -10%) but with a thinner apparence.. The head is narrower, the body appears longer and the bone structure is slightly lighter. The hindquarters are more developed and the pelvis is wider (FFC, 2000).


Figure 1 :The different parts of a rabbit's body.
Source: Barone et al., (1973)
  The head  

The rabbit's head has many tactile hairs or vibrissae (figure 2a below).

The relatively small, ventrally situated mouth has two lips. The upper one is divided in the ventral half (hare's beak). There are long hairs called vibrissae on the upper lip and on anterior part of the cheeks. They carry out the important function of being "contact" elements.

The nose includes two oblique nostrils. The rhinarium, just above the mouth, is a hairless Y-shaped area. The philtrum is the vertical band that crosses the upper lip. The nasal cavities are situated on the diverging parts of the Y-shape. When the muscles contract the surrounding skin covers the hairless area, thus obliterating the nose - figure 2b & 2c - (Grassé and Dekeyser, 1955).
     
Figure 2a. Lateral view of a rabbit's head with the tactile hairs. Source: Barone et al., (1973).
Figure 2b. View of a rabbit's face, mouth and nose. Source: Barone et al., (1973).
Figure 2c Active nose of a rabbit
     

There are some vibrissae on the eyes which has three eyelids each. Two of them move vertically and are covered in hairs on the exterior. They also have cilia. The third lid is between the eyeball and the other two lids, in the internal angle of the socket. It lacks hairs and only covers one third of the eye. It is the nictitating eyelid.

 
  The ears   The ears cover the head and are situated slightly backwards. They are covered in short hairs, mainly on the exterior, and have powerful cartilaginous support. The size of the ears varies a lot depending on the genotype. Dwarf breeds have very small ears (less than 1/5 of the body length) and English Lop-type rabbits have fully-developed ones, which are sometimes as long as the body. If they are generally carried upright, the ears can also naturally fall on the side of the head; we then speak of rabbits of the lop type. Figure 3 shows an illustration of the different sizes and earplugs.
     

Erected ears
in the Flemish Giant

 Ears hanging down
in the French Lop		 Small ears
in dwarf rabbits in general		 Oversized ears
in the English Lop
Figure 3: Size and carriage of ears for different breeds of rabbit
     

The blood vessels on the edge and in the centre of the ear are easily visible. The marginal vein of the ear is a prime site for injections or extracting blood, but other vessels can also be used.

 
  The teats  

On the ventral side of the body there are two rows of 4 -5, and on rare occasions, 6 teats, which means that a doe may have an even number of functional teats (8 or 10 nipples) or an odd number (9 or, more rarely, 11 nipples). Each nipple, endowed with 5 or 6 central secretor canals, has a separate mammary gland. In certain populations efforts in selecting over prolificacy have favoured an increase in the proportion of does with more nipples (table 2).

Due to the good hereditability of this criterion (Szendrö et al, 1992), does with 12 nipples can be seen when the selection pressure is maintained (Coisne, 2000). Systematically, there are two pectoral nipples between the front legs, near the 7th and 8th ribs, and another two between the thighs. Any variation in number always occurs in the ventral ones, which are the easiest to reach during suckling.
Table 2. Percentage of rabbit does with 8, 9 or 10 nipples in a non-selected control line (77T) and two lines selected for their litter size. (77S and 66S).
Source: Rochambeau et al. (1988). - (1) 2 does with 11 nipples out of 929 observed. (2) 2 does with 11 nipples out of 191 observed
Number of
nipples
Lines
77 T
77 S
66 S
8
41.0%
29.9%
22.5%
9
32.4%
33.5%
26.7%
10 or 11
26.6%
36.6% (1)
50.0% (2)
Limbs  
The anterior limbs are short and feets have 5 digits, each with a long curved nails, but digit number 1 ( thumb) is not functional. The posterior limbs are longer and feets only have 4 digits, also with a long, curved nails.. The quantity and quality of hair under the feets is variable from one breed to the other : e.g. very important by the New Zealand White and in smaller quantity by the Champagne d'Argent. The better the quality / quantity of hair under the feets, the greater the ease of raising the breed on wire mesh floor
  Skin glands  

Similar to all other leporids, rabbits do not have funtional sweat glands (tubule glands), but the sebaceous alveolar glands are abundant (Grassé and Dekeyser, 1955). The specialized tegumentary glands are as follows:

  1. Anal glands, which open in the rectum
  2. Fully developed inguinal glands. This is a group of sebaceous glands in the inguinal region that open out into a sac-shaped invagination, the interior of which is lined with short hairs.
  3. Male prepuce glands and female clitoris glands
  4. A submandibular gland behind the lower lip (about 6 mm long by 3 mm wide), consisting of a large number of sebaceous glands that the rabbit uses to mark its territory. (chin gland)
  5. Pigmentary glands consisting also of several sebaceous glands situated in the rhinarium of the nose
Figure 4. Skin glands and teats in the female rabbit.
Source: Barone et al., (1973).

 

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