Gastrointestinal (GI) Stasis- Hairballs Syndrome

Introduction
Physiology
Pathphysiology
Cause
Symptoms
Diagnosis
Treatment
Prevention

Introduction

Gastrointestinal (GI) stasis  is a common cause of digestive disease in rabbits (lagomorphs). In most cases at our hospital the cause is a diet that is too low in fiber. You will sometimes read the term "ileus" when talking about this disease. Ileus occurs when the normal intestinal movement of food through the intestines, called peristalsis, stops. Normal digestion is dependent on normal peristalsis of the intestines. Peristalsis is the movement of ingesta down the stomach and intestines. When this stops GI stasis is the result.

Sometimes a hairball (also called wool block) is considered a part of this disease. In reality, over many years of treating rabbits we have learned that any hairball in the stomach is a result of GI stasis and not the cause of it. Ingesting hair is a normal part of a rabbits life, and when fed the proper food this small amount of hair passes through the digestive tract normally.

This page contains graphic pictures of rabbit necropsy pictures. This is a good way to understand the rabbit's digestive anatomy. It might not be appropriate viewing for all ages.

Digestive Physiology

Herbivorous animals like horese, rabbits, deer, cows, antelopes etc., obtain their nutrition by digesting food that carnivores cannot. A lot of this food is made up of cellulose. Neither carnivores or herbivores contain the enzymes necessary to digest this cellulose. The secret that herbivores have that allows them to digest this usually undigestible food lies in bacteria that reside in their GI tract.

Some herbivores are called foregut fermenters. This means the bacteria that help these animals digest cellulose reside at the beginning of the digestive cycle. Sometimes this occurs in the rumen, one of the so-called 4 stomachs in a cow. These stomachs are actually large fermentation chambers that contain the bacteria that can digest cellulose. Examples of this cellulose are hay and grasses.

In this anaerobic environment, the bacteria consume the plant material for their own metabolic needs and, as a result, produce end-products of fermentation called volatile fatty acids (VFA).  Additionally, the fermenting bacteria use nitrogen from plant material to produce amino acids and protein which can then be used by the animal. Once these bacteria digest this cellulose they produce volatile fatty acids (VFA's) and amino acids. These nutrients are absorbed as they pass through the small intestines and into the large intestine.

In contrast, hindgut fermenters store these bacteria in the cecum (appendix) and large intestine. In the case of the rabbit, there is a complex interaction between the colon and the cecum(appendix) that gets this bacterial fermentation process started. The VFA's and amino acids that are now the end product of bacterial metabolism pass into the large intestines and out the body. They do not get a chance to pass through the small intestines because of their location, and as a result, less nutrition is absorbed by the herbivore.

Here is a picture of the cecum taken during a routine necropsy of a rabbit. The top white arrow on the left points to just one of the 4 horizontal folds of this rabbits cecum. As you can see, it is huge and takes up a large amount of the abdominal cavity. For perspective, the arrow on the lower left points to the uterus in this female rabbit, and the arrow on the lower right points to the urinary bladder.

Here is an x-ray view of the abdomen of a rabbit. This rabbit is laying on its right side, and the head is towards the left. The cecum is that long and horizontal dark object at the bottom. It is dark because it is filled with gas from the digestive process. The white arrow points to it.  Notice also the folds that can be seen radiographically.

Hindgut fermenters have a problem that foregut formenters do not. As we mentioned earlier, since the bacteria are in the cecum they are at the end of the digestive system in the rabbit, and thus there is very little intestines to absorb the volatile fatty acids and amino acids produced by the bacteria before they get excreted by the body. The walls of the cecum can absorb some of the VFA's that are produced. There is not enough intestine though to absorb the proteins and amino acids.

To get around this rabbits have evolved a sophisticated form of coprography (eating feces). In essence, and usually at night (they are sometimes called night droppings), the rabbit literally puts it mouth by its anus and eats some of its fecal matter. This literally brings the nitrogenous proteins and amino acids to the beginning of the digestive tract where they can get absorbed much more efficiently. Usually these droppings are soft in nature and are not the same firm and dry droppings you normally observe in abundance from your rabbit.

This whole system in the rabbit is designed around a high fiber (cellulose) diet. This is why feeding concentrated rabbit pellets is not healthy, and can lead to a shut down of this whole digestive process. This will lead to GI stasis and the potentialf or serious disease, pain, and even death in a rabbit.

Pathophysiology

As the intestines slow down food and hair can become stuck, leading to pain and a further slow down of the intestines (called ileus). A hairball can now form in the stomach adding to the problem. Harmful bacteria can now produce in great quantities and cause the intestines to fill with gas. They overwhelm the normal bacteria and can even produce toxins. This intestinal distention with gas causes even more pain and further ileus. It becomes a positive feedback cycle until the rabbit stops eating and becomes weak and dehydrated. It is at this point most people bring their rabbit in for us to give medical care. This whole process can take anywhere from several hours to several days. It can be slow and insidious or acute and quite apparent that something is wrong. In any case you need to seek immediate medical attention for your rabbit.

In the past this disease was erroneously thought to be a hairball problem. It was treated surgically where we literally did a surgery to open up the stomach and remove the hair and ingesta that was present. Unfortunately, most of these rabbits did not do well postoperatively. As time went on and we learned more about this disease it became apparent that the hairballs were a result of the GI stasis problem and not the cause of this. SInce then we have treated this disease medically with much greater success. Successl depends on how soon in the disease process we treat your rabbit.

Cause

There are numerous causes to this problem:

1. Dental Disease

Rabbit teeth continuously grow. If their dental anatomy is imperfect an incisor or molar tooth can overgrow and prevent them  from being able to chew their food. This will cause the GI tract to stop working and lead to stasis. Our Dental Disease link can give you examples of overgrown teeth.

This rabbit has overgrown incisors preventing normal chewing.

2. Adhesions from prior abdominal surgery

Probably the most common abdominal surgery performed on a rabbit is an OVH (commonly known as a spay). On very rare occasions the healing process can cause adhesions between the uterus and GI tract, making the normal peristalsis movements abnormal.

3. Infections

A sick rabbit can easily spike a fever causing it to become anorectic (not eating). When food is not continuously present in the rabbit GI tract is shuts down leading to GI stasis.

Some infections (urinary tract or abscess) can cause pain, which will also lead to anorexia. Pasteurella, a very common rabbit infection, can also has the potential to lead to GI stasis.

Inappropriate use of antibiotics, especially home use with the wrong antibiotic at the wrong dose, can disrupt normal bacteria (called normal GI flora) and add to this problem.

4. Pain

A rabbit that is in pain will become anorectic, which can lead to GI stasis. The pain can be from numerous causes like fractures, bladder stones, infections, and post operatively.

A fracture like this can be so painful your rabbit will stop eating. This fracture is in the front leg of a rabbit.

5. Stress

Overheating in the summer time, food that is not fresh, new pets or environment, or sudden changes in diet can lead to so much stress that your rabbit stops eating. This rapidly leads to dehydration and GI stasis. In a household with more than one rabbit the separation of the rabbits can be stressful.

6. Intestinal blockage

This is a rare cause of GI stasis in rabbits. Even though rabbits cannot vomit they don't tend to eat foreign bodies like bones, needles, threads, and yarn like dogs, cats, and ferrets.

7. Inadequate fiber in the diet

This is the cause we see most commonly in our hospital. Your rabbit should be fed grass hay like timothy hay along with dark leafy greens. It should be feed mininal to no concentrated pellets. These pellets were formulated for convenience and for breeding rabbits that needed the concentrated energy. High fiber in the diet helps to properly wear down the rabbits teeth that grow continuously through life.

Symptoms

Symptoms can be subtle and easily missed, especially at the early stages. The two primary symptoms to watch for are complete or partial anorexia (lack of appetite) and a diminished amount of droppings. Sometimes these droppings will be quite dry and firm. Other symptoms could be lethargy and signs of discomfort when you pick up your rabbit or touch it. Bunnies that are painful will grind thier teeth. They might start eating strange objects like paper and wood to increase the fiber in their diet.

Please keep in mind that GI stasis can occur simultaneously with other diseases, especially when these other diseases are the cause of the problem. We discussed some of these causes earlier.

Diagnosis

This is not a disease you should diagnose at home and then try a home remedy. This is because other diseases can mimic GI stasis, other diseases can be occurring simultaenouesly, and also because by the time you notice a problem the disease is already well entrenched. The longer you wait for an accurate diagnosis the poorer the prognosis becomes.

Our diagnosis of GI stasis follows the diagnostic process like it does for all our patients. You might want to link to the diagnostic process to learn about it before continuing on GI stasis.

Signalment-

GI stasis tends to occur in middle aged and older rabbits of any gender.

History

Rabbits with this problem tend to be feed a diet that does not have enough fiber. There might be a history of prior surgery, trauma, or a stress related episode like boarding your rabbit in a strange environment. Maybe a home medication was used that disrupted the normal bacteria in the intestines  (GI flora).

Physical Exam

Our doctors perform a thorough exam to determine the exact nature of your rabbits problem. This is important since other diseases can mimic GI stasis. We will weigh it and take its temperature as a start. We will check the molar and incisor teeth carefully for any problems. We will check lymph nodes and palpate the abdomen, along with checking the heart with a special stethoscope for small animals. We will also determine your rabbit's state of hydration.

When our exam is completed we will give you an assessment of your rabbits condtion and review all the potential disease that might be affecting your bunny.

Diagnostic Tests

Routine tests include a blood panel, urinalysis, and fecal exam for parasites. It is also common to take a radiograph to check for other problems and confrim the diagnosis.

Different rabbit, different view. This rabbit is on its back, with the head at the top, arrow pointing to the stomach. The dark area at the top on each side is the lungs that are in the thorax. Everything below this dark area is in the abdomen.  Notice how large this distended stomach is. This has the potential to be a GI stasis problem just like the radiograph above.

If one of our doctors suspect more than GI stasis he/she might want further diagnostic testing. This might include special blood titers and ultrasound.

Treatment

Most cases are treated in our hospital. These rabbits need medication and nursing care, at least initially, that can only be properly performed by our techncians. Some rabbits respond well in 1-2 days and start eating and producing droppings. Others can take 1-2 weeks to get back to normal function. Patience is importance because the rabbit GI tract is sensitive and overzealous treatment can do more harm than good.

Fluids

Many of these rabbits are dehydrated and need fluids. We give them orally, intravenously or subcutaneously.  The fluids replace electrolytes, provide vitamins, and rehydrate your rabbit. Rehydration is important in general for any sick animal, and is especially important in GI stasis to help with normal peristalsis and movement of ingesta through the intestines.

Assist Feeding

The GI tract needs to get back to normal function asap. I lack of food will shut down the GI tract and cause ileus, adding to the GI stasis. As we are rehydrating we will also assist feed special food called Critical Care. This stimulates the peristalsis movement of the intestines and adds badly needed nutrients.

Feeding a proper diet

We give timothy hay along with dark green wet vegetables like Kale. The fiber and moisture present in this food is an aid in getting the intestinal peristalsis going again. Alfalfa hay is not recommended because of excess calcium and protein.

Other good foods to feed are dandelion, mustard greens, parslely, carrot tops, broccoli, melon, oranges, mango, tomatoes, and kiwi.

Medication to stimulate the intestines

The two primary medications used in rabbits to stimulate the intesines back to normal peristalsis are Cisapride and Reglan. They are highly beneficial and used in most cases.

Pain medication

These rabbits are in significant pain due to the distention of the intestines. This pain needs to be addressed if they are to begin eating again. Typical medications include narcotic pain killers and the NSAID Metacam.

Antibiotics

Antibiotics are not routinely used, and can even disrupt the normal bacteria in the intestines. If we determine your pet has an infection from its lab data or physical exam we will put it on a broad spectrum antibiotic. Common organisms the proliferates in the cecum in GI stasis are E. Coli and  Clostridium.

Treatments we do not do

Some treatments have the potential to make the problem worse. Probiotics and yogurt have milk starches and sugar that can feed the Clostridium bacteria. Lactobacillus has not been shown to be of any benefit, and if it is stressful to give this orally to your bunny could actually be detrimental. The same applies when you try to feed your rabbit "night dropping". The proper word for night droppings is cecotropes. Hairball remedies can also cause a problem. The enzymes in pineapple are unable to dissolve a keratin mass in the stomach, and might even provied the Clostridium with sugar so it can keep on proliferating in the cecum.

Home Care

Once your rabbit is eating and producing droppings in increased frequency, and if the lab data is normal, we will send your bunny home with you to finish the nursing care. Our doctors will tell you what to do and our staff will demonstrate how to adminster this home care. We are always here to help you, and if you cannot do it we will continue to hospitalize your bunny or treat it on an out-patient basis.

If you have other rabbits at home let them interact together as long as you can monitor the eating habits and droppings of the sick one.

Prevention

Minimizing stress (heat, overcrowding), proper diet (high in timothy and other grass hays, minimal pellets), a clean environment, fresh drinking water at all times, can be a substantial help in minimizing this serious problem. Do not let your rabbit become obese.  Bring your rabbit in for an exam at the earliest sign of any problem with appetite or droppings.