Rabbit digestive system
Photo and Text: Margaret Woods
Abdominal cavity of a rabbit, with the gastrointestinal tract in place. Craniad is to the left of the photo, caudad is to the right.
The abdominal cavity is opened by making a careful incision down the median
of the rabbit, just below the diaphragm. The incision does not need to be deep,
so that you can preserve the structures directly dorsal. Continue the incision
inferiorly to the rabbit's pubic symphysis. Make two cuts perpendicular to the
first incision on each side just above the pubic symphysis, so that one can
better reflect the cut skin. Observe the orientation of the digestion system
in the abdominal wall [See Figure 15]. Observe how the large intestine occupies
the right and mid section of the abdominal wall, while the small intestine occupies
the left and lower section (just above the pubic symphysis). Observe the relation
of the stomach to the liver. The huge lobes of the liver are located anterior
to the stomach and a lobe is also located to the right of the stomach. Probing
under the liver, one can observe where the esophagus joins the stomach. Probing
under the stomach, one can observe where the stomach joins the small intestines
(the pylorus). Lifting the stomach from its left side, one can observe the spleen,
which is a long slender structure. To remove the stomach, one has to cut it
out anteriorly and posteriorly. Anteriorly, an incision can be made midway through
the esophagus. One also has to cut the stomach away from the liver, which may
lead to the inability to preserve the posterior surface of the liver. Posteriorly,
an incision can be made just about the rectum.
After removing the digestion system, one can lay it out to see the length of
the segments. This requires untangling the intestines starting with the small
intestines (from the pylorus) and following the intestines to the end. One will
have to cut the mesentery, which attaches sections of the intestinal tract to
one another. Only cut mesentery where it is necessary, so that the blood vessels
within it can stay preserved. The mesentery makes untangling the intestines
rather difficult, especially when you get to where the small intestines lead
into the large intestine; it looks as if the intestine is going into two different
directions. If it becomes too difficult, stop cutting and then just visually
follow the tract to the end (which requires a lot of rotating of the tract,
so try not to tangle up what has already been untangled). It is like a maze,
if one way does not get you to the end, then start from that same point of confusion
and try the other way. Then continue to cut and untangle.
Once the intestinal tract is untangled, lay it out in such a way that you can
clearly see the path of the tract from the stomach to the end. One can then
start to observe the structures that could not be seen while the digestion system
was in the abdominal cavity. One can observe the spleen again, which lays on
the left side of the stomach. In the mesentery, connected to the intestine (not
much of a distance from the stomach), one can observe the pancreas. The pancreas
in the rabbit is not of a solid body form, but of a glandular form spread through
out a small section of mesentery. Following the intestinal tract from the small
intestine to the large, at that point, one can see the extremely large caecum.
At the end of the caecum, one can observe the appendix (which is extremely hard
to differentiate from the caecum).
After observation, one can cut open and rinse out parts of the stomach, small,
intestine, and large intestine and compare the internal textures. The internal
texture of the stomach is extremely smooth and the stomach wall is very thin.
However, the internal texture of the small intestine is smoother than that of
the stomach and the wall is thinner. The internal texture of the large intestine
is rough and very rigid and the wall is extremely thick in comparison to that
of the stomach and the small intestine.
| Critter | Relative length of gut segments | What did they eat? |
| Rabbit (O. cuniculus) | It has a divided intestinal tract with a relatively proportional stomach. The length of the small intestine is not very much longer than the length of the large intestine. The diameter (of the lumen) of the small intestine is not much smaller than that of the large intestine. The caecum is extremely large in comparison to the rest of the intestinal tract, with a diameter about four time that of the large intestine. | Fibrous plants |
| Bat (Myotis) | It has an undivided intestinal tract that is relatively small to the stomach size. | Insects |
| Dog (Canis) | Its intestinal tract is divided, with a stomach proportional its size. The small intestine is much longer in comparison to the large intestine. However, the diameter of the small intestine is about equal to the diameter of the large intestine. The caecum is extremely small in comparison to the rest of the intestinal tract, with a diameter smaller than the rest of the tract. | Flesh |
| Horse (Equus) | The intestinal tract is divided with an extremely small stomach relative to the rest of the tract. The length of the small and large intestines are proportion. However, the diameter of the large intestine is much larger than that of the small intestine. The caecum is extremely large having the diameter of the larger intestine. | Fibrous plants |
| Sheep (Ovis) | The intestinal tract is divided, with a larger stomach in comparison to the rest of the tract. The small intestine is extraordinarily longer than the large intestine. The diameter of the small intestine is not much smaller than that of the large intestine. The caecum is relatively small with a diameter close to that of the large intestine. | Fibrous plants |
| Kangaroo (Macropus) | The intestinal tract is divided with an extremely larger stomach in comparison to the rest of the tract. The small intestine is relatively longer than the large intestine (about twice its length). The diameter of the small intestine is not much smaller than that of the large intestine. The caecum is proportional to the rest of the intestinal tract with a diameter close to that of the large intestine. | Fibrous plants |
comparisons based on lab handout.
O. cuniculus has an extremely large caecum relative to the rest of the intestinal tract for hindgut digestion.
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