Rabbit Gastrointestinal Syndrome: A Clinical Review

DoveLewis Veterinarian Sarah Tauber, DVM, reviews gastrointestinal syndrome in rabbit patients.

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Gastrointestinal stasis is one of the most commonly treated conditions in rabbits, especially in the emergency setting. Often GI stasis is seen as a result of poor husbandry, however other underlying diseases, stress conditions or discomfort may also be a trigger. We often do not get the luxury of being able to perform diagnostics, or provide inpatient intensive care to severely affected rabbits. In these cases, the history and exam findings and rapid medical management become increasingly important.

Delays in treatment can be life-threatening. GI stasis is thought to be either primary or secondary, however, it is not technically a diagnosis. Gastrointestinal stasis is a symptom of a larger problem. Rabbits are strictly herbivores, with a simple stomach and hindgut cecal fermentation. The role of fiber is multifactorial, making it the most important component to a rabbit’s diet. Fiber creates a healthy gastric environment, promotes normal GI motility, adequate fermentation, and normal foraging behavior. Generally, extraneous triggers or concurrent diseases cause a change to motility and general dysbiosis of the gastric lumen and cecum. This causes food accumulation in the stomach, decreased transit time, alterations in gastric pH, and further exacerbates the clinical signs. Ultimately these changes cause a ball of ingesta or hair (from normal grooming) to accumulate in the stomach which becomes dehydrated and compact and worsens anorexia, discomfort and dysmotility.

Obtaining a History

Rabbits typically present with either a few hour or multi-day history of decreased appetite or anorexia, decreased stool passage and decreased water consumption. Some owners are more astute than others, and may pick up on early signs before complete anorexia occurs. Rabbits will typically decrease their intake of hay and pellets first, losing interest in treats last. Treatment may vary pending the duration of clinical signs.

Quizzing owners on environment, housing and stressful conditions will help give clues to predisposing factors of gastric stasis. Ensure housing remains clean, discuss substrates and ensure rabbits are given the opportunity to ingest their cecotrophs normally. Free roaming house rabbits may have more opportunity for mischief making, including dietary indiscretion, chewing on cords, stress in the house, or trauma that may lead to either primary or secondary gastric stasis. Recent hospital visits, surgeries, medications, metabolic disease, dental disease, or decreased exercise may also lead to a GI stasis event.

 

Diet

An inappropriate diet is not only a predisposing factor for GI stasis, but for other diseases. It is one of the most common mistakes that can cause gut dysbiosis. Detailed information on diet should be obtained in the history, including sources of fiber, what type of hay is fed, type and amount of pellets fed, and greens, veggies and treats offered both daily and on special occasions. Some rabbits adapt over time to a poor diet, so trends and acute diet changes should be highlighted.

Fiber is imperative for normal dental attrition, intestinal motility and bacterial fermentation, and should be 20-25% of the rabbit diet. A large component of fiber intake is indigestible, playing a critical role in stimulating motility and controlling transit time. Fiber also affects a rabbit’s drive for voluntary food intake and normal cecotrophy. Larger fiber particles allow for a more penetrable food ball in the stomach which allows gastric acid to destroy bacteria, and will stimulate normal peristalsis. If a rabbit is only ingesting small fiber particles through inadequate hay or smaller pellets, this will lengthen GI transit time and time spent in the cecum which increases the potential for cecal dysbiosis. This can predispose rabbits to bacterial enteritis and may cause a dehydrated trichobezoar or food accumulation in the gastric lumen which will perpetuate GI stasis. Timothy hay is a preferred fiber source due to the fiber and protein content. Other leguminous hays are higher in protein and calcium which may predispose rabbits to obesity and potential formation of uroliths.

Protein content should be approximately 12-16% of the normal pet rabbit diet with excessive protein causing cecal dysbiosis and bacterial overgrowth. Increased carbohydrates, mainly with treats, may not be digested due to rapid GI transit time. Undigested carbohydrates will accumulate in the cecum and will contribute to enterotoxemia.

Pellets are not necessarily required as long as the appropriate hay and greens are part of the normal diet. Multiple types are on the market, and mixes with colorful treats can catch the eye of consumers. Rabbits offered pellets in a mix will pick out the goodies like a kid eating all the marshmallows from the box of Lucky Charms.

This can be a common culprit of GI disease and gut dysbiosis with rabbits consuming increased sugars and carbohydrates and less fiber. If pellets are offered, recommend timothy pellets only, no mixes, and a larger pellet size. Pellets should be offered in moderation, not free fed, measuring approximately ¼ cup per 5 lbs rabbit per day.

Fresh greens and vegetables listed below should also be offered, but in moderation with approximately two cups per day for an average rabbit. Fruits should be offered sparingly (high sugar and carbohydrates). Any new foods should be only offered in small amounts and introduced gradually.

  • Great: Lettuce (romaine, green, red), collard greens, spinach, dandelion greens, cilantro, parsley, carrot tops, beet tops, basil, fresh grass (however not grass clippings)
  • Sparingly: fruits, carrots, tomatoes, kale
  • Avoid: the cabbage family (broccoli, cabbage, cauliflower, brussel sprouts, bok choy), nuts, beans, grains, dairy products and meat

Physical Exam

While some rabbits can present with lethargy, others may be bright and alert in the hospital setting. This is why a full physical exam should always be performed. A thorough dental exam can be performed with either an otoscope or a speculum to evaluate the oral cavity completely, noting any dental points, ulcerations foreign bodies or lesions. Rabbits may mask their signs of discomfort in the hospital setting, but hints may have been noted as part of the clinical history, including reserved behavior, bruxism, hunched stance. The abdomen may palpate as tense or uncomfortable. With gastric stasis, the stomach is typically smaller with dehydrated contents; marked dilation of the stomach may make other differentials of gastric bloat more likely. The small intestines and cecum will likely be gas distended; however, it may be deceiving due to the stage of digestion. Borborygmi are typically noted to be decreased to absent. Other signs of illness should be noted, including cachexia, unkept haircoat, ectoparasites, respiratory changes, which may indicate other underlying disease and secondary stasis.

Diagnostics

The history and physical exam may be suggestive of gastric stasis, however diagnostics will help to confirm or rule out differentials of either primary or secondary GI disease. In sick or decompensating rabbits, initial stabilization should be considered before causing additional stress to a rabbit. Acute or mild cases may not require diagnostics, and often rabbits will respond to supportive care. However, diagnostics should be strongly considered in rabbits not responding to initial treatment or with more chronic or severe signs.

Figure 1: Lateral abdominal radiograph of a rabbit showing mildly enlarged stomach with ingesta, ingesta in the cecum, and moderate gas diffusely through the small intestines. Consistent with mild functional ileus.

 

Radiographs

Common findings include an ingesta filled stomach with a history of anorexia, and moderate to severe gas distension of the intestines and cecum. Small gas bubbles can be normal, but diffuse gas distension (less than two times the second lumbar vertebrae) is indicative of GI stasis. Marked gas or fluid distension of the gastric lumen could be more consistent with causes of obstruction. Abdominal ultrasound may be required to diagnose obstruction, trichobezoar, neoplasia, or other underlying diseases.

Figure 2: Lateral abdominal radiograph of a rabbit showing severe gastric distension with fluid and gas, moderately distended small intestinal segments. These findings indicate a higher concern for obstructive process with stasis less likely.

CBC, chemistry: Will help to assess the overall condition and stability of the patient, and may unmask other conditions.

 

Differentials

As previously discussed, GI stasis is most commonly a result of environment, stress, or diet, but other differentials should always be considered. The following is a list of other disease processes to consider:

  • Gastric dilation (fluid or gas): more indicative of obstruction (trichobezoar, foreign body, neoplasia, herniation, other)
  • Hepatic lipidosis: prolonged anorexia will predispose rabbits
  • Adhesions post OHE, other surgery: may present like an obstruction
  • Primary infectious: secondary dysbiosis from recent medications (antibiotics, other), parasitism (coccidia, Eimeria, other), viral (rare)
  • Toxins
  • Non-GI cause with secondary effects: renal dysfunction in older rabbits, liver torsion, sepsis

Treatment

Depending on the duration of clinical signs and physical exam findings, treatment may be approached on an outpatient basis or via hospitalization. General and mild cases of GI stasis can typically be treated with basic supportive care. The mainstay of therapy are fluids and pain management with important considerations to prokinetics and heat support.

Intestinal discomfort from ileus and gas distension will further worsen GI motility. If there are any indications of discomfort and strong consideration for GI stasis, pain management is warranted. Treating the discomfort will help to improve food intake and fecal output and hopefully GI motility. Buprenorphine (0.01-0.05 mg/kg SQ or IV q 6-12 hrs) is a great option to start. Midazolam may be considered to minimize stress in obtaining diagnostics, or IV catheter placement if warranted. NSAIDs may be considered, however are only recommended once a patient is better hydrated and once other underlying diseases are ruled out. More severe cases that are hospitalized may benefit from a lidocaine CRI.

Rabbits have higher fluid requirements than dogs and cats; approximately 100-120 ml/kg/day for maintenance needs. Fluid therapy is aimed to correct the underlying deficits with important considerations to ongoing losses, hypovolemia. With mild cases, administration of daily fluid requirement SQ (warmed) may be effective, given in 2-3 administrations. In more severe cases, IV fluids should be considered. IV catheter sites are recommended in a cephalic or marginal (lateral) ear vein. Critical patients may require an intraosseous (IO) catheter. Special precautions should be made to prevent rabbits from nibbling on the fluid line, including using flexible coiled IV tubing or wrapping the lines. 

Patients should be stabilized, and warmed before nutritional support is started. Most cases should be started on critical care grind via syringe feedings. This diet is high in fiber, palatable, and helps to rehydrate stomach contents. Rabbits will typically tolerate the feedings well. Nasogastric tube placement may be considered in more critical patients, patients that do not tolerate syringe feedings well, or where is severe gastric distension. Free access to hay and healthy greens should continue to be offered during treatment.

Promotility agents can be controversial, however are for the most part recommended. In cases of confirmed GI stasis, metoclopramide at 0.5 mg/kg SQ or PO q 12 hrs is started, or cisapride (0.5 mg/kg PO q 8-12 hrs) for upper and lower GI motility. Concurrent use of ranitidine has synergistic effects. Owners should be cautioned about risks if a GI obstruction is suspected. As long as informed consent is obtained, promotility drugs should still be given even if obstruction cannot be definitively ruled out.

Antibiotics are not recommended and not routinely used unless clinically indicated. They may be considered with concern for pathogenic bacteria. Enrofloxacin or trimethoprim sulfa are fair options.

Repeat physical examinations and close clinical monitoring are required throughout the course of treatment. We hope to see a response to therapy within 1-2 days, but in some cases, it can take 3-5 days. In severe cases, or cases not responding to management, more aggressive therapy and diagnostic testing should be pursued. Serial radiographs imaging may be required, and abdominal ultrasound should be considered if not already performed. Rabbits that do not respond to initial treatment may have an underlying disease that has not yet been treated or may just require more aggressive management. Overall, rabbits have a good prognosis to survive if appropriately managed and owners are diligent with treatment, monitoring, and future prevention. In a 2019 article evaluating 117 rabbits with GI tract dysfunction, approximately half of rabbits show recurrence of GI stasis. Hypothermia below 97.9 and pursuit of surgery were negative prognostic indicators for survival.

Prevention

Prevention of gastric stasis is achieved by feeding rabbits an appropriate diet with special focus on high quality diets that are high in fiber. Rabbits should be encouraged to exercise and keep a healthy weight. Stress in the household should be kept low, with special attention to changes in the environment such as the addition of new pets or people in the house. Rabbits should be regularly groomed to prevent excessive hair intake. Appropriate enrichment should be provided to improve boredom and encourage normal foraging behavior. Despite appropriate husbandry and diligent rabbit care, rabbits may still be at risk for gastric stasis. With mild cases, rabbits have a good prognosis. However with complications, underlying disease, or need for surgical intervention, acute decompensation is possible.

 

References

A. Lennox. “Top 10 Emergency Presentations for Exotic Companion Mammals” IVECCS 2019 preceedings.

K Quesenberry, J. Carpenter. “Gastrointerstinal Physiology and Nutrition”. Ferrets, Rabbits and Rodents. 2012

“Healthy Rabbit Diets”. www.rabbitadvocates.org/care-info

N. Antinoff. “GI stasis in rabbits- to cut or not to cut”. Chicago Vet 2019.

T. Riggan. “Rabbit gastrointestinal physiology and function- stasis and obstructive disease”. Southwest Veterinary Symposium 2018.

Oparil KM, Gladden JN, Babyak JM, et al: Clinical characteristics and short-term outcomes for rabbits with signs of GI tract dysfunction: 117 cases

(2014-2016). J Am Vet Med Assoc 2019. Vol 255 (7) pp. 837-45

E. Brooks. Gastrointestinal stasis in rabbits. Vincyclopedia of diseases: Exotic pets.

Lichtenberger M, Lennox A: Updates and advanced therapies for GI stasis in rabbits. Vet Clin North Am Exot Anim Pract. 2010. Vol 13 (3) pp. 525-41

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