Contributors: James Simpson, Kenneth Simpson

 Species: Feline   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading



  • Examination of the colonic and rectal mucosa.
  • Collection of colonic mucosal biopsy samples.
  • Investigation of:
    • Chronic diarrhea.
    • Hematochezia.
    • Dyschezia.
    • Tenesmus.


  • Non invasive technique requiring no surgical intervention.
  • Well tolerated by sick cats which would be unsuitable for laparotomy.
  • Requires light general anesthesia - rapid recovery.
  • Good visualization of the alimentary mucosa.
  • Follow up examination well tolerated and useful for to assessing response to treatment.


  • Will not detect pathology lying under the mucosa.
  • Not routinely possible to examine the entire small intestine.
  • Cannot carry out surgical correction compared with laparotomy.
  • Expensive equipment.

Technical Problems

  • Technical difficulty in procedures.

Alternative Techniques

  • Radiography Radiography: abdomen and fluoroscopy contrast studies (barium series) of the alimentary tract.
  • Ultrasonography: examine ileocolic region and colonic wall.
  • Exploratory Laparotomy: midline.

Time Required


  • Induction of anesthesia and/or sedation   →   10-30 minutes.


  • Depends on the experience of the endoscopist   →   approximately 15-30 minutes.

Decision Taking

Risk assessment

  • Low risk.
  • See complications.



Nursing expertise

  • Good level of competence required for assisting in procedures, monitoring anesthetic and assisting in biopsy collection and handling.
  • High competence for care and cleaning of endoscopic equipment.

Materials Required

Minimum equipment

  • Fully immersible fiber optic flexible or rigid endoscope.
  • One meter insertion tube length.
  • Insertion tube diameter 6-8 mm.
  • ONLY use an end viewing endoscope.
  • Four way tip deflection.
  • MUST have cold light source with air pump, suction and water wash facility.
  • Fenestrated biopsy forceps for collection of mucosal biopsy samples.
  • Cleaning brushes for biopsy channels.
  • Water leakage tester.

Ideal equipment

  • video endoscope
  • Excellent magnified image presented on screen.
  • Detection of lesions much easier.
  • Allows for multiple person viewing.
  • Excellent for video recording procedures and/or collecting still images.
  • Excellent as a training aid.
  • Xenon light source.
  • Insertion tube diameter 6-8 mm.
  • Suction unit for aspiration of unwanted gastrointestinal secretions and air.
  • Cytology brushes, grasping forceps and balloon catheters.
  • More than one endoscope for examination of different parts of the gastrointestinal tract.
  • Endoscope cleaning cart.
  • Ultrasonic cleaner for biopsy forceps.

Minimum consumables

  • Clean water.
  • Endoscope cleaners and disinfectants.
  • Household detergent.
  • Formal saline, card and containers for preservation of biopsy samples.

Other requirements

Care and maintenance

  • Storage of endoscopes:
    • ALWAYS store endoscopes in a safe location where accidental knocks can be avoided.
    • ALWAYS store endoscopes with insertion tube hanging vertically.
    • Do NOT store endoscopes in their carrying case.
    • See supplier for further details of endoscope 'hangers'.
  • Cleaning and disinfection Endoscope: cleaning:
    • Follow the manufacturers recommendations at all times.
    • Use an endoscope cleaning bath wherever possible.
    • Use whatever cleaners and disinfectant the manufacturer recommends.
    • Follow health and safety rules regarding use of these products.


Dietary Preparation

  • Nil by mouth for a minimum of 24 hours.


Other Preparation

  • Preparation essential to permit good visualization of mucosa.
  • Microlax enema on afternoon prior to procedure.
    Bandage tail to reduce soiling and aid location of anus in long-haired breeds.



Step 1 - Pass endoscope

  • Lay patient in left lateral recumbancy.
  • Lubricate distal end of endsocope with KY gel.
  • Gently insert endoscope into the rectum and inflate with air.

Core Procedure

Step 1 - Endoscopic examination

  • The colon is short in the cat.
  • Once mucosa is visualized Colon: normal submucosa - colonoscopy slowly advance the endoscope examining the mucosa as you proceed.
  • Air may have to be continually used to maintain visualization but do NOT overinflate.
  • Try to advance endoscope to the ileocecocolic junction.
  • This will be recognized as a 'button-like' structure with a small blind-ended sac immediately adjacent (cecum).
  • Flexures separating the descending/transverse and transverse/ascending colon are recognized as 'bends' as the endoscope is advanced Colon: flexure - colonoscopy .
  • Collect biopsy samples from any focal lesion and from all levels of the colon.
  • Unlike other endoscopic procedures, the rectum is best examined when gently withdrawing the endoscope while maintaining air inflation.

Step 2 - Biopsy collection

  • Collect biopsy samples from any focal lesion and from all levels of the colon.
    Do not overinflate the bowel as this will make mucosa stretch tightly reducing ability to collect samples.
  • Try and advance biopsy forceps perpendicular to the mucosa.
  • Tent mucosa before closing biopsy forceps and retrieving sample.
  • Deeper samples can be collected by sampling repeatedly at the same site.
  • Perforation will occur if this is done too frequently.
  • Capillary bleeding from biopsy sites is normal.


Step 1 - Remove endoscope

  • Gently withdraw endoscope.
  • Support end of scope with swab as it is withdrawn to prevent damage.



General Care

  • Routine post anesthetic observation.
  • Check mucus membrane color, heart and respiratory rates in case of hemorrhage.

Special precautions

  • Do not overinflate bowel. Apply only enough air to allow adequate visualization.

Potential complications

  • Arterial bleeding from biopsy sites.
  • Bowel perforation from applying too much force.
  • Iatrogenic damage to mucosa caused by advancing endoscope along bowel.


Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Jones B D (1990) Endoscopy of the lower gastrointestinal tract. Vet Clin North Am Small Anim Pract 20 (5), 1229-1242 PubMed.
  • Roth L, Leib M S, Davenport D J et al (1990) Comparisons between endoscopic and histologic evaluation of the gastrointestinal tract in dogs and cats - 75 cases (1984-1987). JAVMA 196 (4), 635-638 PubMed.

Other sources of information

  • Tams T R (1998) Small Animal Endoscopy. 2nd edn. CV Mosby, St Louis.
  • Simpson J W (1996) Gastrointestinal Endoscopy. In: Manual of Canine and Feline Gastroenterology. Eds: D Thomas, J W Simpson, E J Hall. BSAVA, Cheltenham. pp 20.