The simple faecal floatation procedure is suitable for the isolation and identification of a majority of nematode eggs and protozoan (oo)cysts in canine faeces. The method is quick, inexpensive and does not require use of a centrifuge.
Flotation solution (e.g. saturate salt or sodium nitrate)
Preparation of flotation solutions of specific gravity (S.G.) 1.20:
Sodium nitrate solution
Dissolve 315 g sodium nitrate in approximately 700 ml warmed distilled water (dH2O). Add more dH2O until the entire solution weighs 1200 g (this equates to a S.G. of 1.2). Mix solution and then check S.G. with hydrometer.
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). Check S.G. with hydrometer.
- Place ~2 g faeces into a wide-mouthed plastic disposable cup
- Add ~44 ml flotation solution to the jar and mix with faeces thoroughly
- Add a further 4 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 10-15 mltest-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 22 x 22 mm coverslip on top of the test tube
- Stand for 10–15 min
- Carefully lift off the coverslip from the tube, with the drop of fluid adhered to the bottom of it, and place it on a microscope slide.
- Examine under a light microscope at low power (10x) for helminth stages and at high power (40x) for protozoal stages.
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
- 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