How the Rabbit Digestive System Works
The rabbit's digestive system is unique and complex compared to other mammals. Because rabbits are herbivores, they eat a variety of plants and in large amounts. The rabbit's digestive system is equipped to handle the large quantity of fiber from eating these plants. What makes the rabbit's digestive system even more unique compared to other mammals is that it can separate nutrients from plants that are typically indigestible to other mammals. Their digestive system's strategy is to use a process called hind gut fermentation.
To fully understand this process, starting at the beginning will help. The rabbit uses its prehensile lips to grasp the plant and then bites off the plant with its front teeth, also known as incisors. Once in the mouth, the plant is pushed back to the molars where it is chewed into very small pieces and mixed with enzymes from the rabbit's saliva. Then the rabbit sends the food down the esophagus by swallowing.
Once passing the esophagus, the food will enter the stomach. A rabbit's stomach is relatively large in reference to the size of a rabbit. In the stomach, the food is sterilized by acid and then enzymes begin to break down the food for digestion.
The plant food is then pushed into the small intestines. In the small intestines, more enzymes are produced to break down the food further. This allows the nutrients to be extracted and pass through the lining of the small intestines to be absorbed into the blood stream. Sounds fairly normal, right? Well, here comes the uniqueness of the rabbit's digestive system.
What is left in the small intestines is passed into the colon. Since the enzymes can't break down the fiber in plants, it is left up to the colon to sort it out. The colon sorts out what can still be digested and sends it on to an organ called the cecum to break down the food product even further.
Inside the cecum, yeast, bacteria, and other organisms work hard to break down the food into something that can be further digested as nutrients. Once broken down, the cecum sends the mixture coated in protective mucus back to the colon. This is where the rabbit's digestive system gets a bit disgusting to some people.
The colon then pushes out the mucus-covered mixture called cecotropes. Rabbit owners have often referred to this as night droppings. Often they look like a cluster of small, moist grapes. Generally, most rabbits will consume cecotropes as they are exiting their anus. For the most part, it will just appear as though the rabbit is grooming itself. Typically rabbits will do this at night or during early morning hours.
Once the cecotropes are consumed, they are passed through the rabbit's digestive system just as the plant food did. Nutrients are absorbed through the lining of the small intestine, on to the blood stream, and then what can't be absorbed is pushed back to the colon.
The colon then takes what is indigestible and turns it in to waste. This is what most people see as rabbit fecal droppings. They look different from cecotropes. They are typically hard, round to oval pellets and the rabbit knows not to eat these. Cecotropes are not only moist but are typically brown or green in color and is accompanied by a strong, foul odor.
It is rare to actually see cecotropes. If the rabbit has left some cecotropes in its cage, especially in large quantities, it is advised to take the rabbit to the veterinarian. It could be simply that there is too much protein in the rabbit's diet or it could be due to a more serious condition that requires a veterinarian's help
Kathleen M. Clark, DVM did a wonderful presentation on the Basics of the Rabbit Gastro-Intestinal Tract. There are four parts to the video above. It is very informative for those who want to have a better understanding of the rabbit's digestive system and rabbit nutrition.
© 2014 L Sarhan