Page 147 - The Veterinary Laboratory and Field Manual 3rd Edition

116 Susan C. Cork and Mani Lejeune

faeces to 15 ml of water and take the required
aliquot (15 ml) for further processing.

Preparation of a standard suspension
1 Break up the faecal specimen with a fork.
2 Weigh 3 g of faeces and place in a bowl.
3 Pour about 30 ml of water into the bowl and
macerate the faeces.
4 Sieve the sample through a tea strainer to
remove fibrous/coarse material.
5 Wash the suspension with water into a beaker
(or open necked bottle) previously marked to
reach an indicated volume of 45 ml, thus the
sample is suspended in a final ratio of 1 g in
15 ml water.
6 Thoroughly mix the suspension and dispense
15 ml into one or two 20 ml round-bottomed
centrifuge tubes.
7 Centrifuge briefly (low level [1500–
1
2000 rpm] setting for 10 min) and decant the
supernatant.

Figure 3.2 The use of a plastic bag to protect hands
from direct contact with faecal material if water- Methods to detect helminth life stages
proof gloves are not available. (eggs, larvae, and so on) in faeces

of parasite stages (eggs/larvae) present in the The choice of method for parasite detection
samples, it is important to measure and record depends on the purpose for which the test is
the weight of the sample and the volume of performed. A direct faecal smear can be pre-
preservative fluid if added (see later). ferred for a quick parasitic disease diagnosis of
a terminally sick animal. In contrast, more com-
prehensive parasitology testing is performed
Processing for disease assessment, either in an individual
animal or in population. In general, comprehen-
The preparation of a standard suspension of sive testing utilizes protocols that concentrate
faeces is the first step in the examination of a parasite stages in faecal samples. This can be
faecal sample. Make a note of the colour, smell, performed in a qualitative or quantitative man-
consistency and texture of the sample. Thorough ner. Qualitative techniques are those that can be
mixing of the faecal sample is required before used to determine the relative number and vari-
suspension because parasite eggs (especially ety of parasite eggs present in a sample, these
tapeworms) may not be evenly distributed in are often simple to perform and do not require
faecal samples. If possible make a large volume a lot of laboratory equipment. Methods which
(150 ml) of suspension with the ratio of 1 g allow a more accurate assessment of parasite

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