Gastrointestinal Tract Disease in Small Herbivores

Gastrointestinal Tract Disease in Small Herbivores

Dr. Heidi Hoefer, RUSVM

Key Species Covered

  • Chinchilla

  • Rabbit

  • Guinea pig

Learning Objectives

  • Understand rabbit digestive anatomy and physiology.

  • Identify and treat gastrointestinal (GI) stasis.

  • Identify and treat bloat in rabbits.

  • Explore causes of diarrhea in exotic companion mammals (ECM) herbivores.

Digestive Anatomy and Physiology

Hindgut - Fermenting Herbivores

  • All teeth are open-rooted.

  • Monogastric with large cecum.

  • Strict herbivores requiring high-fiber diet.

  • Complex digestive tract; disruption may lead to stasis syndrome.

Herbivore Gastrointestinal Tract Overview

  • Characteristics:

    • Large stomach and cecum.

    • Non-distensible stomach; inability to vomit; anything ingested remains within, including grooming fur and non-dietary items.

Gastrointestinal Tract Stasis

Definition

  • Commonly presenting problem in herbivores.

  • Described as a "syndrome" rather than a disease.

  • Generalized ileus results in decreased peristalsis, stool production, and appetite.

  • A syndrome consists of a collection of symptoms whose causes are not fully understood.

Types of Ileus

  • Mechanical ileus:

    • Caused by obstructions such as hairballs, tumors, or intussusception.

    • Note: GI tumors are rare in herbivores.

  • Paralytic ileus:

    • Characterized by a generalized loss of peristalsis due to lack of motility.

    • Most common form in rabbits; difficult to distinguish sometimes.

Causes of Gastrointestinal Stasis in Herbivores

  • Fur plugs: Contributing to mechanical ileus.

  • Low-fiber diet: Insufficient insoluble fiber hinders motility.

  • Extreme stress or fear: Can induce ileus.

  • Surgery/anesthesia: May lead to decreased motility post-op.

  • Kidney disease: Can affect digestive health.

  • Neurological disease: Impacts gut function.

  • Pain experiences: Anything causing pain and anorexia or stress.

Common Causes of Pain in Rabbits

  • Arthritis: Typically seen in older rabbits.

  • Pododermatitis: Inflammation of footpads.

  • Dental issues: Including spurs or root abscesses.

  • Ear infections: Can lead to pain and distress.

  • Liver torsion: Presents as acute abdomen.

  • GI gas: Painful condition that may go unnoticed.

Diagnostic Tools and Techniques

Radiographs (X-rays)

  • Used to screen for potential painful conditions and assess gas patterns.

  • It is not uncommon to find no specific cause during assessment.

Common Causes of Pain in Guinea Pigs

  • Arthritis: Seen in older guinea pigs, particularly in stifles.

  • Pododermatitis: Similar to rabbits.

  • Dental issues: Require attention.

  • Middle ear infections: May cause head tilts.

  • Uroliths: Calculi that can cause significant pain.

Gastrointestinal Stasis: Diagnosis

  • History: Assess for hyporexia (reduced appetite) or anorexia.

  • Clinical signs: Observation of little or no stool production.

  • Abdominal palpation: To feel for gas or ingesta in the gastrointestinal tract.

  • Blood testing: To rule out secondary causes.

  • Radiographs: Critical in diagnosing GIT stasis. Ensure to include blood chemistry panel for acutely sick rabbits.

Imaging Findings

  • Normal rabbit radiograph: Shows no abnormalities.

  • Excess food in the stomach with hindgut gas: Indicates potential issues needing immediate attention.

Gastric Bloat in Rabbits

Differentiation from Generalized Ileus

  • Stomach becomes full of fluid and gas, posing a risk of rupture.

  • Immediate emergency treatment is required.

Clinical Presentation

  • Typically present as acutely moribund.

  • Considered an outflow obstruction.

  • Rare for rabbits to develop volvulus; however, guinea pigs’ stomachs can torse.

  • Hypothermia is indicative of shock (temperature < 99°F).

  • Immediate gastric decompression via tube insertion is crucial.

  • IV shock treatment is mandated.

  • High mortality rate observed; re-bloating indicates a need for surgical intervention.

Gastric Decompression Technique

  • Sedation necessary to suppress the gag reflex.

  • Use of a 14-16 French feeding tube and speculum/mouth gag.

  • Perform gentle suction and warm water lavage through the tube.

  • Administer medications via tube, such as cat hairball treatment and sucralfate (if bleeding is observed).

Gastric Bloat in Guinea Pigs

  • Similar acute presentation as in rabbits.

  • May indicate outflow obstruction; torsion of the stomach is a possibility.

  • Procedure involves checking stomach location on radiographs, ideally located on the left.

  • Percutaneous gas aspiration and gastric tube suction may be necessary.

  • High mortality due to late presentation.

GI Stasis: General Principles of Therapy

  • Fluid Replacement:

    • Administer enteral and parenteral fluids to hydrate gut contents with thin oral feedings.

  • GI Motility Modifiers: Required to enhance gut movement.

  • Pain Management: Critical for animal comfort and recovery.

  • Gastric Decompression: Necessary if bloated.

  • IV Shock Fluids: Administer if the animal is hypothermic.

GI Stasis: Specific Treatment

  • Parenteral Fluids:

    • Use Lactated Ringer’s solution at 100 ml/kg/day, given subcutaneously (SQ) or intravenously (IV).

  • Pain Management:

    • Lidocaine CRI for painful, shocky, or bloated cases, especially postoperative.

  • Motility Medications:

    • Administer Metoclopramide and Cisapride to facilitate gut motility.

  • Analgesics:

    • Use buprenorphine or hydromorphone.

  • Anti-nausea Medications:

    • Maropitant (Cerenia®) can be helpful.

  • Antacids:

    • Famotidine recommended for gastric health.

  • Success Indicator:

    • Passage of normal stool is a key outcome measure.

Gastric Ulcers Treatment

  • Gastric ulcers are common in rabbit populations.

  • Hold NSAIDs initially; use antacid therapy with famotidine (1 mg/kg) or omeprazole (1 mg/kg).

Nutritional Support in GI Stasis

  • Assist-Feed Syringe Formula: Important in keeping nutrient intake.

  • NPO (Nil per os): No food if bloated; this protects against further distress.

  • Dietary Adjustments:

    • Use low-sugar formulations and high-fiber preparations.

  • Recommended Products:

    • Oxbow Critical Care® and LaFeber Emeraid Herbivore® are suggested for nutritional support.

Antibiotics in GI Stasis

  • Indications:

    • Consider antibiotics for long-standing cases, in shocky, hypothermic rabbits, or with mucoid feces.

    • Target anaerobes in cases with mucous production.

Mucoid Enteropathy in Rabbits

  • Typically observed in baby rabbits but may affect adults with digestive disturbances.

  • Characterized by mucous production in the hindgut; linked to bacterial overgrowth, specifically Clostridium sp. and endotoxemia.

  • Initial treatment includes doxycycline and injectable penicillin G.

  • High mortality rates in afflicted young rabbits.

Inpatient vs. Outpatient Treatment Considerations

  • Assess stress levels of the rabbit and owner.

  • Evaluate ability to provide a quiet cage environment.

  • Determine how long the rabbit has been in gut stasis.

  • Consider the age of the rabbit and results from blood tests.

  • Monitor body temperature; severely dehydrated, painful, or hypothermic patients should stay in the hospital.

Body Temperature in Rabbits

  • Normal Temperature: 101-104°F

  • Hypothermia: Below 100°F indicates shock.

  • The lower the temperature, the higher the mortality risk; temperatures below 94-98°F are particularly concerning.

  • Treatment for hypothermic patients should include IV shock fluids, heat application, and supportive care.

Surgical Considerations

  • Surgery should be selected carefully due to high mortality rates associated with procedures in small herbivores.

  • Often, medical management is effective.

  • Gastric torsion in guinea pigs and liver torsion in rabbits typically necessitate surgical intervention or euthanasia.

Gastrointestinal Complications

  • Necrotic gut from endotoxemia: Surgery is not a solution to necrotic tissue.

Hairballs in Herbivores

  • True trichobezoars are uncommon among small herbivores.

  • A high-fiber diet can prevent hair accumulation.

  • Factors contributing to hairball issues include high-shedding periods and cage-mate grooming behaviors.

  • True hairballs can be visualized in radiographs showing hair mats within the stomach.

Liver Torsion in Rabbits

  • Commonly observed in young (1-3 years) and lop-eared rabbits.

  • Symptoms include acute anorexia and weakness.

  • Blood work often shows elevated liver enzymes and anemia.

  • Complications include hemo-abdomen and potential fatality.

  • Diagnosis is best made via ultrasound or CT; rarely detected on radiographs.

Diarrhea in Rabbits

  • Distinguishing between uneaten cecals and true diarrhea is vital.

    • Cecals produced once daily; normal stool observed otherwise.

  • True diarrhea is considered a medical emergency.

  • Rule out uneaten cecals and check fecal wet mount for coccidia (Eimeria), which infects primarily young rabbits.

    • Adult rabbits are usually immune; treatment options include sulfa drugs or ponazuril.

  • Pinworms: Common and generally of low pathogenicity.

  • Bacterial dysbiosis: May result from incorrect diet or antibiotic use. Standards for fecal exams include verifying presence of pinworm eggs and coccidia.

Diarrhea in Guinea Pigs and Chinchillas

  • Similar assessments apply; rule out factors such as:

    • Antibiotic use.

    • Dietary factors.

    • Bacterial presence.

    • Coccidia and Giardia infections.

    • Nematodes are considered rare.

  • For all diarrhea cases, a fecal wet mount necessary for laboratory examination for ova, parasites, and Giardia testing.