Fecal analysis: microscopy

• Examination of fresh fecal samples for the presence of undigested starch, fat or muscle fiber Fecal analysis: overview.
• No such material should be present in health.

Alone

• Simplicity of method to assess maldigestion Maldigestion , eg the results may support a putative diagnosis of Exocrine Pancreatic Insufficiency (EPI) Exocrine pancreatic insufficiency.

Disadvantages

• Presence of food components (starch, fat or protein) is not specific for any disease.
• Putative diagnoses likely to need further diagnostic tests, eg EPI should be confirmed with Trypsin Like Immunoassay (TLI) testing Blood biochemistry: trypsin-like immunoreactivity.

Alternatives

• Carry out a serum TLI test, which is definitive for EPI.

Risk assessment

• Observe Health and Safety regulations when handling feces, stains and other in-contact consumables.

• Ensure starch, fat and muscle is present in the diet before collection of feces.
• Collect fresh fecal samples for examination.

Equipment

• Microscope.
• Staining rack.
• Microscope slides.
• Sudan3 stain.
• Lugols iodine stain.
• Spatulas.
• Fecal containers.
• Pipettes.

• Collect fresh feces in a suitable container.
• Using a spatula apply a thin film of feces to 2 microscope slides.
• Place slides on staining rack.
• Flood 1 slide with Lugol's iodine Fecal analysis: Lugol's iodine and the other with Sudan 3 stain Fecal analysis: Sudan 3.
• Leave for 5 minutes.
• Decant excess stain.
• Dry underside of slide.
• View under low power (eg x4) microscopy for black starch granules (Lugols stain) and for red fat granules (Sudan 3 stain).

Disposal

• Dispose of consumables and fecal material following Health and Safety regulations.

• Test procedures easily carried out in practice laboratory with little additional technical skill required.

• Poor staining technique.
• No starch, fat or muscle fiber in the diet.
• Fecal smear too thick.

Refereed papers

• Recent references from VetMedResource and PubMed.

Other sources of information

• Manual of Small Animal Clinical Pathology (1998) Eds: Davidson M, Else R & Lumsden L. BSAVA, UK.
• Clinical Textbook for Veterinary Technicians (1998) 4th edn. Ed: McCurnin. W B Saunders.
• Laboratory Procedures for Veterinary Technicians (1997) 3rd edn. Ed: Pratt. Mosby.