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Sluggish Motility in the Gastrointestinal Tract 
Susan Brown, DVM
 

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My rabbit hasn't pooped in about three days. My friend says he has a hairball in his stomach and I should give him pineapple juice, papaya enzyme tablets, Prozyme and a cat hairball laxative to dissolve the hairball. This doesn't seem to be working. Why did he get a hairball and what should I do?

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The diagnosis of "hairball" or "wool block" is commonly made in rabbits. This is a condition that doesn't really exist in the opinion of a growing number of veterinarians who care for rabbits. By that I mean that the primary problem is not a hairball, but rather a problem with sluggish motility of the gastrointestinal tract (GIT) leading to dehydration and impaction of material in the stomach and cecum.

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So how does this happen? One needs to look at the GIT physiology of the rabbit to understand this condition. As discussed in HRJ Vol. III, No. 3, the indigestible fiber in the diet "drives" the digestive tract or, in other words, determines the speed with which ingesta moves along. When there is an insufficient amount of this type of fiber present, motility may be slowed.

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Let's review the GIT of the rabbit to look at all the parts (see figure, right). The stomach holds the food and essentially sterilizes it with a pH of 1 to 2. The food then moves out through the small intestine where nutrients are absorbed into the body. At the junction of the small intestine and the large intestine is a large blind sac called the cecum. This is where the digestible fiber and other portions of the diet that need to be fermented are deposited. A variety of microorganisms break down this material in the cecum and convert it into nutrients such as fatty acids, amino acids and vitamins. (Please note that Lactobacillus or Acidophillus are not significant microorganisms in a rabbit's cecum). The nutrient-rich material is then excreted in the form of cecotropes (some people call these "night feces") which are eaten directly from the anus by the rabbit and redigested.

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When the speed with which material moves through the GIT is altered it can affect how quickly the stomach and cecum empty. If the motility is reduced as in diets that are too low in indigestible fiber, then the stomach and cecum will empty slowly. The rabbit eventually stops eating and drinking probably due to a feeling of fullness in the stomach. When there is no food coming into the system the GIT motility slows to almost a standstill. Water is still needed by the body and it is extracted from the stomach and cecal contents. A vicious cycle is now set up. The longer the rabbit doesn't eat, the more dehydrated and impacted the material in the stomach and cecum becomes and the less the rabbit feels like eating. Add to this a diet too high in protein or starch and the result can eventually be disastrous. Diets too high in protein and/or starch can result in changes in the cecal pH and thus the types of microorganisms growing there. These fragile communities are altered, allowing the growth of bacteria such as Clostridium spiriformes which can result in death due to the production of iota toxins.

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So where does the hair come from? Rabbits always have some hair in their stomach contents. They groom themselves constantly and swallow the hair. A true "hairball" is comprised of nearly 100% hair as in the cat or the ferret. In the rabbit, the hair is mixed with ingested food in a mass. As this material dehydrates, the larger particles are left behind (which includes the hair). The liquid stomach content gradually becomes a solid tightly adhered mass. The stomach contents feel doughy and firm on palpation. Radiographs reveal a solid mass of material in the stomach, often with a distinctive halo of air around it .

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To sum it up, the cause of this condition is not the presence of hair in the stomach, but rather a GIT motility disorder that results in firm impacted stomach and cecal contents. If we do not correct the underlying problem, then this condition is destined to reoccur.

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How do rabbits act when they have impacted stomach or cecal contents? They will stop eating either suddenly or gradually over a period of time. The stools will get smaller and smaller, then stop altogether. Often, these patients will be bright and alert for a week or longer. They may want to chew the paper on the bottom of the cage, the woodwork or the wall board (all sources of fiber they are craving), but refuse to eat their pellets. Some rabbits have had periodic soft, pudding-like stools prior to complete anorexia. Eventually these patients can become seriously ill and die if the condition is not treated.

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How do we treat a stomach impaction due to reduced GIT motility once it happens? It is important to make sure that all the conditions that may be affecting the rabbit are detected. Your veterinarian may suggest x-rays or other lab work. Since this is an impaction problem, the goal is to rehydrate the rabbit both through the circulatory system and through the GIT. Fluids are administered either under the skin or in a vein along with high fiber and moisture feedings by syringe or tube. Syringe feedings can be made from ground rabbit pellets or powdered alfalfa mixed with blenderized green leafy vegetables and an oral electrolyte solution. In addition, medications to stimulate the GIT to start moving again and analgesics are used. It is rarely necessary to use antibiotics, and in fact these might cause further disturbance to an already compromised GIT. Some people like to use laxatives, and enzymes. I too, have used these products in the past, but have found that they really aren't necessary. I have equal success in treating this condition with or without enzymes. It is important to remember that enzymes of any kind (pineapple, papaya or pancreatic) do not dissolve hair. But the real keys are hydration of the stomach/cecal contents and getting the GIT moving again.

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I find that over 50% of the rabbits presented with this condition will take care of it themselves when they are given a big pile of leafy greens to eat. Most of the cases of stomach impaction we see have been on a primary pellet diet and have had little or no access to greens or hay. They are craving fiber and fluids and the leafy greens can be just the ticket. In addition we give all these patients good quality grass hay. We completely remove pellets from the diet (rabbits usually won't eat pellets when they are ill anyway). Whatever treatment is used, one can expect stools to be produced within three days. It is rarely necessary to perform surgery for this condition.

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Other causes of GIT disease in the rabbit include partial or complete blockages of the intestine with foreign material (often carpet fibers), post-surgical adhesions, intestinal parasites, toxins (such as lead) and other systemic disease. It is important to have your rabbit thoroughly examined by your veterinarian to determine all the problems prior to instituting the treatment that I have described.

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So, how do you prevent this situation? It really isn't difficult. The nature of the GIT physiology of the rabbit suggests that it is vitally important to provide a diet that is high in indigestible fiber as was discussed in HRJ Vol. III, No. 3. This is easily provided in the form of grass hay (oat, timothy, bermuda, etc.). Grass hay is lower in calcium, protein and calories than legume hay such as alfalfa. Hay should be provided 24 hours a day. This way, the pet will never go hungry and will always have a source of nutrition and fiber. The next important part of the diet are fresh leafy greens. Dark leafy greens provide not only good fiber, but moisture (as well as other nutrients), and the moisture helps to keep things mobile. As quoted in HRJ Vol. III, No. 4, you should use at least three different types a day so as to provide a variety of nutrients and tastes. Examples include dandelion greens, kale, mustard greens, romaine, endive, carrot tops, parsley, etc. In my opinion rabbits can have as much of these foods as they want as long as they are eating the hay well. However, if you have never fed greens to your pet, it is best to introduce hay first for a couple of weeks and then add in the greens gradually over a few weeks. In this manner, it is unlikely that your rabbit will experience any digestive problems. Rarely a rabbit will have a "reaction" to a food item and produce a soft stool. Just eliminate this food from the diet. Other vegetables and fruits can also be given such as apples, pears, peaches, berries, pea pods, broccoli, papaya, mango, kiwi, tomatoes, melon, oranges, etc. Wash all fresh foods thoroughly as you would for yourself. Stay away from high starch foods such as legumes (peas and beans) and grains. Clean water should always be available in a water bottle or heavy crock bowl. You will notice that your rabbit will drink far less water on a diet high in greens than on one that is composed primarily of pellets.

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As was discussed in HRJ Vol. III, No. 4, for the non- breeding houserabbit the least important part of the diet is the pellets. These concentrated food sources were designed originally for rabbits in production (for food or fur) and for laboratory rabbits. They are packed with calories and vitamins and minerals. Non-breeding houserabbits do not need these extra calories and they produce most of their own vitamins through their cecotropes when provided a diet high in hay and fresh foods. I rarely recommend pellets as part of the diet for these pets unless I am trying to get weight back on a rabbit or in cases where hay cannot be given because it is unavailable or the humans in the household are allergic to it. We have seen hundreds of rabbits (including my own three; a Flemish Giant, a mini rex and a mixed breed) that are in excellent condition on a hay and fresh food diet alone. These rabbits rarely experience GIT disease.

It is so frustrating for me in practice to see the same myths perpetuated about "hairballs" and to see this disease used so often as a primary diagnosis. Let's stop using the term "hairballs" and replace it with "stomach/cecal impaction due to reduced GIT motility". Understand that impaction is not a cause of disease but the result of underlying GIT problems. This condition is 99% preventable with an appropriate diet. It is unnecessary to routinely use laxatives, enzymes and other supplements. Let's stop trying to play "catch up" treating stomach crises all the time and feed our pets the type of diet they were designed to eat. *

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"To sum it up, the cause of this condition is not the presence of hair in the stomach, but rather a GIT motility disorder that results in firm impacted stomach and cecal contents."

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Susan Brown, DVM is the co-owner of Midwest Bird and 
Exotic-Animal Hospital in Westchester, Ill.

References

Cheeke, P.R. 1987. Rabbit feeding and nutrition. Orlando: Academic Press, Inc.,

15-33.

Harkness, J.E., and J.E. Wagner. 1995. Biology and medicine of rabbits and rodents. 4th ed. Baltimore: Williams & Wilkins.

de Blas, C. 1992. The roles of fiber in rabbit nutrition. J. Appl . Rabbit Res. 
15:1329-1343.

Aderibigbe, A.O., Y. Tor-Agbidye, P.R. Cheeke, and N.M. Patton. 1992. Interactions of fermentable carbohydrate and protein on nutrient digestibility, performance and enteritis in weanling rabbits. J. Appl . Rabbit Res. 15:1225-1234.

Gidenne, T. 1992. Rate of passage of fibre particles of different size in rabbit:

Effect of the dietary lignin level. J Appl Rabbit Res. 15:1175-1182.

Maertens L. 1992. Rabbit nutrition and feeding: A review of some recent developments. J. Appl . Rabbit Res. 15:558-913.

Brewer, N.R. 1991. Biology of the rabbit. Vol 8. Synapse 24:29-33.

Lelkes, L., and C. Chang. 1987. Microbial dysbiosis in rabbit mucoid enteropathy. Lab. Anim. Sci. 37:757-64.

Lelkes L. 1986. Overeating and microbial imbalance in the development of mucoid enteropathy in rabbits. J Appl Rabbit Res. 9:148-51.

A proper diet is central to maintaining optimum health and can prevent a number of disorders. This volume of the House Rabbit Journal has already presented several articles discussing various aspects of a healthy rabbit diet. In a two-part series by Elizabeth TeSelle in issues 3 and 4, part 1 emphasized the importance of fiber in the form of hay for gut motility.

Part 2 examined commercial rabbit pellets and the place of fresh vegetables in a balanced diet. In issue number 5, Dr. Kestenman addressed the role of diet in the treatment and prevention of bladder disease and bladderstones, focusing on the importance of relatively low calcium levels. In this issue, Dr. Susan Brown, who was extensively quoted in our first two diet articles, explains the true nature of "hairballs" and their prevention and treatment, in which diet plays a very important part.