Gastrointestinal Stasis Syndrome in Pet Rabbits

Overview

Gastrointestinal (GI) stasis is the common term used to describe a syndrome of reduced or absent GI motility and its consequences in rabbits. It is by far one of the most common disorders seen in pet rabbits. Very often, it is caused by an inappropriate diet. However, stress is a common initiator of decreased GI motility, so any illness, painful condition, or stressful event can trigger an episode. Rabbits with GI stasis will eventually stop eating, and a lack of food in the intestinal tract will exacerbate GI stasis. Left untreated, GI stasis can rapidly become life-threatening.

The Role of Fiber

To understand the pathogenesis of GI diseases of the rabbit, the normal anatomic and physiologic aspects of rabbit digestion must be appreciated. In rabbits, the main driving force for normal intestinal motility is the presence of large quantities of indigestible fiber. Lack of this fiber, caused by either dietary inadequacies or conditions that cause anorexia, is a major cause of GI stasis. Fiber stimulates cecocolic motility, either by a distention effect of the bulk or directly. Diets high in fiber promote the production of specific volatile fatty acids in the cecum that promote peristalsis. Inadequate ingestion of coarse fiber will inhibit normal GI peristalsis. Rabbits ingest hair routinely in the process of grooming. An inappropriate diet or GI stasis can disrupt the balance of this complex cecal microflora and the environment in which it grows. Diets low in fiber cause cecocolic hypomotility, prolonging the retention of digesta in the cecum and ultimately producing changes in cecal microflora.

History and Clinical Signs

During physical examination, obtain a complete dietary history, including the type and amount of commercial pellets, hay, leafy greens, and treats. Rabbits with a regular diet consisting primarily of pellets without adequate fresh hay supplementation are at increased risk for development of GI stasis. The risk is even higher in rabbits fed rations consisting of a mix of dried fruits, vegetables, seeds, nuts, grains, and pellets. Acute episodes of GI stasis and dysbiosis are common in rabbits after ingesting a large volume of high-carbohydrate, high-fat treats. Rabbits at low risk are those fed diets of unlimited, good-quality, high-fiber grass or timothy hay, a moderate amount of fresh leafy greens, minimal pellets, and no or only occasional treats. Stress alone, including stress caused by pain or concurrent disease, can cause GI stasis. Question the owner about recent potentially stressful events such as changes in housing, introduction of new rabbits or other pets, recent illness, trauma, or surgery, or any underlying disease processes. Common underlying disorders that may cause anorexia are dental disease, chronic upper respiratory tract disease, neurologic disorders, lower urinary tract disease, and renal or hepatic disorders. Many rabbits with stasis will have a history of little or no routine exercise. In rabbits with GI stasis, the most common presenting complaint is a gradual decrease in appetite over 2 to 7 days and subsequent decrease in fecal production. Left untreated, rabbits will eventually stop eating entirely. Water consumption also is often decreased. Feces become scant, dark, dry, and small, eventually ceasing altogether. Owners may report a corresponding decrease in activity, due to abdominal pain. Rabbits in pain are reluctant to move, appear less social, may grind their teeth, may dig or scratch, and sit in a hunched position.

Physical Examination Findings

Rabbits with stasis generally appear alert and quiet, exhibiting little or no sign of lethargy. In suspect cases, palpate the abdomen with careful attention to the stomach contents, intestines, and cecum. The size and consistency of the stomach are key in differentiating GI stasis from obstructive disorders. With GI stasis, stomach size may vary with the duration of disease, but it always contains ingesta, as opposed to fluid and gas seen in rabbits with obstructive disorders. In GI stasis, fluid is pulled from the stomach, eventually leading to stomach contents that feel firm, doughy, and remain pitted on compression.

Diagnostic Testing

Radiographs are very helpful in the diagnosis and essential to differentiate GI stasis from obstructive disorders. Radiographic changes vary with the severity of illness, but in all cases, the stomach will contain ingesta. Presence of an ingesta- filled stomach in a rabbit that has been inappetent for several days is suggestive.

Treatment

The key principles in the treatment of GI stasis are to rehydrate the patient and stomach contents, alleviate pain, provide nutrition, and treat any underlying disorders. Treatment consists of the following:

• Fluid therapy – to maintain circulation and rehydrate GI contents. In mild cases, oral fluids may be all that is required, but in more severe cases intravenous fluids are indicated. Maintenance volumes are 100 ml/kg/day.

• Analgesia – buprenorphine (0.01–0.05 mg/kg s/c or i/v q8h), butorphanol (0.1–0.5 mg/kg s/c or i/v q2–4h), carprofen (2–4 mg/kg s/c or i/v q24h).

• Motility modifiers (contraindicated if a blockage is suspected) – metoclopramide (0.5 mg/kg s/c q12h); cisapride (0.5 mg/kg p/o q12h); ranitidine (2–5 mg/kg p/o q12–24h).

• Assisted feeding – commercially available high-fibre herbivore recovery diets, slurries of ground rabbit pellets, vegetable baby foods. Always offer hay.

• Exercise – helps to stimulate GI motility.

• Antibiotics – are not indicated in the treatment of gut stasis.

• Surgical intervention – may be required with a gastrotomy to empty the stomach contents in cases of gastric distension unresponsive to medical treatment. With this case, the rabbit responded to medical treatment over a 3-day period, going on to make a full recovery.