SOP 1: Simple Faecal Float

The simple faecal floatation procedure is suitable for the isolation and identification of a majority of nematode eggs and protozoan (oo)cysts in canine and feline faeces. The method is quick, inexpensive and does not require use of a centrifuge.

Definitions

SG       = Specific Gravity

FF        = Faecal Float

dH20    = Distilled water

Preparation of flotation solutions of SG 1.20:

Sodium nitrate solution

Dissolve 315 g sodium nitrate in approximately 700 ml warmed dH2O. Add more dH2O until the entire solution weighs 1200 grams (this equates to a SG of 1.2). Mix solution and then check SG with hydrometer

Saturated salt

Dissolve salt (~300-400 g depending on purity) in 1000 ml warmed dH2O while stirring continuously. Keep adding more salt until no more dissolves (i.e. salt remains precipitated out of solution once cooled).

Method                                                                     

  • Place ~2 g faeces into a wide-mouthed plastic disposable cup
  • Add ~10 ml flotation solution to the jar and mix with faeces thoroughly
  • Add a further 40 ml flotation solution to the jar and mix again
  • Pour/ Filter this faecal suspension through a tea strainer into a new jar
  • Empty the contents of the jar into a 50 ml test-tube supported in a rack or stand
  • Keep adding contents or top up with floatation solution until a positive meniscus forms over the lip of the test tube
  • Carefully place a coverslip on top of the test tube
  • Stand for 10 – 15 minutes
  • Carefully life the coverslip with the drop of fluid adhered to the bottom of it and place it on a microscope slide
  • Scan for helminth stages under low power (10 ×) and for protozoal stages under high power (40 ×).

For an alternative step-by-step guide with useful images of this procedure, refer to: http://www.rvc.ac.uk/review/parasitology/Flotation/Simple_flotation/Purpose.htm

Safety Precautions

  • Wear lab coat and disposable gloves
  • Wash hands thoroughly when finished

Clean Up Procedures

  • Pour sodium nitrate into appropriate chemical waste container
  • Dispose of all slides and cover slips in a sharps container
  • Clean all equipment (tea strainer, glass test tubes) thoroughly with a 10% bleach solution
  • Wipe down work area with 70% Ethanol