Gastrointestinal Disorders in Companion Animals

Approach to Disorders of the Gastrointestinal Tract

• The gastrointestinal tract (GIT) consists of the oral cavity, oropharynx, esophagus, stomach, small intestine, large intestines, rectum, anus, liver, and pancreas.

Learning Objectives

• Understand how to restrain and perform a comprehensive clinical examination, including history-taking and physical examination, to identify clinical problems and involved body systems.
• Demonstrate a rational, evidence-based problem-solving approach to common presentations in companion animal practice.
• Perform clinical reasoning, including differential diagnoses and further investigations.
• Understand how to take appropriate samples and request appropriate tests.
• Interpret and appraise laboratory reports and clinical data for clinical case management.
• Formulate appropriate treatment, patient care, control, and prevention plans, including euthanasia.
• Critically review and evaluate evidence to support practicing evidence-based veterinary medicine.

Gastrointestinal Disease

• Gastrointestinal disease is very common, with many cases self-limiting.
• Identify cases requiring further investigation/treatment.
• Be aware of clinical presentations of serious illness requiring immediate attention.
• Thorough history-taking is essential, as reported symptoms may not fully represent the true situation (e.g., vomiting vs. regurgitation vs. dysphagia).
• Careful and comprehensive physical examinations are needed as various parts of the GIT are not always easy to assess.
• Excellent client communication is crucial.

Approaching a Case

• Evaluate if immediate treatment is necessary.
• Gather a history.
• Create a problem list.
• Perform physical exams.
• Implement symptomatic treatment.
• Assess if resolution occurs, and act accordingly.

Approaching a Case - Problem-Based Approach

• Address life-threatening conditions immediately.
• Evaluate possible systemic diseases.
• Consider potential differential diagnoses.
• Formulate a treatment plan.

Anorexia

• Anorexia is a loss or lack of appetite to eat (not eating, not wanting to eat, not able to eat).
  • Partial (hyporexia) or complete.
  • True anorexia: decreased appetite, with no interest in eating.
  • Pseudoanorexia: secondary anorexia, hungry but unable to eat due to pain, unpalatable diets, or environmental stress.

Oral Cavity

• Components: Lips and oral mucosa, palate, tongue, teeth, mandible, maxilla, and salivary glands.

Clinical Signs

• General clinical signs: Pseudoanorexia(jaw abnormality, pain), unwillingness to play/pick up toys, hypersalivation, failure to gain weight, halitosis, ceased grooming.
• Other clinical signs: Possible pain or movement abnormalities in the jaw (abnormal movement), pain, unwilling to pick up toys/play ball, hypersalivation, poor or decreased weight gain, problems with oral hygiene (halitosis), ceased grooming.

Dental Disease

• Oral resorptive lesions (feline).
• Fractured teeth.
• Malalignment/malocclusion.
• Cleft palate.
• Overgrowth (equine, rabbit, small mammals - herbivores).
• Abscess (most animals but not rabbits).
• Gingiviits/Periodontitis (canines).
• Gingivostomatitis (feline).

Lips, Oral Mucosa, Gums, Palate

• Neoplasia: Soft tissue sarcoma, squamous cell carcinoma (feline), melanoma, sarcoids (equine).
• Trauma: Penetrating injury/stick injury, tongue laceration.
• Inflammatory/immune mediated: Eosinophilic granuloma complex (feline), lip fold dermatitis (secondary pyoderma). and viral infections (like papillomavirus, calicivirus, feline gingivostomatitis and reoviruses).

Trauma

• Injuries to the oral cavity, tongue, and surrounding tissues.

Viral Infections

• Papillomavirus, calicivirus, feline gingivostomatitis, reoviruses, bluetongue, foot and mouth.

Inflammatory Diseases

• Eosinophilic granuloma (feline), lip fold dermatitis (secondary pyoderma).

Salivary Glands

• Salivary gland mucoceles, sialadenitis, neoplasia.

Jaws

• Fractures/trauma (mandibular symphysis fracture), bacterial infections (actinomyces bovis – lumpy jaw; penetrating injury/abscess), and neoplasia.

Investigation

• History, thorough visual oral exam (sedation may be needed), biopsy & histopathology, culture, viral swab, PCR, imaging (radiographs, CT, MRI, and endoscopy)

Oropharynx

• Components: Tonsils, cricopharyngeal muscles

Clinical Signs (Dysphagia)

• Dysphagia (difficulty swallowing), retching, gagging/gulping, decreased appetite (pseudoanorexia), weight loss.

Disorders (Oropharynx)

• Neoplasia (squamous cell carcinoma, sarcoma, lymphoma), cricopharyngeal achalasia(muscle relaxation issues), cricopharyngeal dysphagia (asynchronous relaxation).

Investigation (Oropharynx)

• Physical examination, visual inspection of the oropharynx, biopsy, CT, and MRI, and endoscopy.

Esophagus

• Narrows at four locations: pharyngo-oesophageal sphincter, gastro-oesophageal sphincter, thoracic inlet, base of the heart.
• A long muscular tube.

Clinical Signs (Esophagus)

• Regurgitation (species variation), hyprexia/pseudoanorexia, ptyalism, weight loss.

Differentials of Regurgitation

• Physical obstruction (extra-luminal causes, like vascular ring anomaly, intra-thoracic mass, foreign body, stricture, tumour, granuloma).
• Functional (lower oesophageal achalasia, sliding hiatal hernia).
• Inflammatory (oesophagitis, reflux syndromes, aerodigestive disorders).

Disorders of the Esophagus

• Oesophageal foreign body (dogs, horses, cows)
• Narrowing (stricture, vascular ring anomaly)
• Megaesophagus (hereditary, secondary to vascular ring anomaly, generalised enlargement, lack of peristalsis).

Investigation (Esophagus)

• History, physical examination, radiographs (CT or MRI), biopsies, endoscopy.

Stomach

• Horse (hindgut fermenter), ruminant (foregut fermenter , monogastric).

Clinical Signs (Stomach)

• Vomiting, cranial abdominal pain, anorexia/reduced appetite, weight loss, reduced performance (horses), abdominal distension, melena (blood in stool).

Stomach Disorders

• Gastritis (acute/chronic), ulcerations (performance animals), neoplasia (uncommon), foreign body, pyloric stenosis, distension (bloat, GDV, gastric impaction, grain overload), displaced abomasum.

Small Intestine

• Components: Duodenum, jejunum, ileum.

Clinical Signs (Small Intestine)

• Hyporexia/anorexia, weight loss, poor growth, abdominal pain (colic), abdominal distension, hypoproteinaemia (low alb), ascites/oedema, dehydration/collapse, decreased or increased gut sounds (borborygmi), flatulence, diarrhoea.

Disorders of the Small Intestine

• Obstruction (foreign body, neoplasia, lymphoma, adenocarcinoma, sarcoma, intussusception, and volvulus), inflammation, ulcers, parasites (e.g., giardia, cryptosporidium), bacterial infection, viral infections (like parvovirus, coronavirus, and rotavirus), fungal infections (e.g., histoplasma, candida).

Investigation (Small Intestine)

• Palpation, auscultation (sound of gut movement), minimum database (haematology, biochemistry, electrolytes, inflammation, protein levels), folate and cobalamin (B12), faecal analysis, radiographs, ultrasound, endoscopy.

Large Intestines

• Structure (hindgut fermenters like rabbits and hindgut fermenters, monogastric digestive).

Clinical Signs (Large Intestines)

• Diarrhoea, weight loss, appetite change, constipation, faecal incontinence, abdominal pain.

Disorders (Large Intestines)

• Obstruction (foreign body, neoplasia, Lymphoma Adenocarcinoma Sarcoma, Intussusception, Volvulus), inflammation, parasites, bacterial/viral infections, toxins, ulceration.

Clinical Signs of Large Intestines Colic, ILeus

• abdominal pain, dehydration.
• ileus symptoms: absence of intestinal movement, poor diet, poor dentition (relevant to rabbits)

Investigation (Large Intestines)

• Digital rectal palpation, faecal analysis, bacterial culture, PCR, parasitology, radiology (radiographs, ultrasound). ( Exploratory surgery might be needed)
• Abdominal examination and palpation, radiographs, ultrasound

Rectum and Anus

• Components: Rectum, anus, anal sacs (dogs and cats).

Clinical Signs (Rectum and Anus)

• Tenesmus (straining to defecate), anal irritation, scooting, licking, biting, change in faecal shape (thin, ribbon-like).

Disorders (Rectum and Anus)

• Strictures, neoplasia (benign, malignant like Adenocarcinoma Lymphoma), rectal prolapse (secondary), perineal hernia, anal sac diseases (impaction, inflammation/abscess, anal furunculosis/fistula, congenital diseases like atresia ani, and rectovaginal fistula).

Investigation (Rectum and Anus)

• Visual inspection, rectal digital palpation, fine needle aspirate, biopsy, endoscopy.

Disorders of the GIT General Considerations

• Assess clinical signs & history for precise location.
• Differential lists.
• Diagnostic tests.
• Client communication.