Collection and Processing of Samples for Parasitology
Feces
Collection
- Ideally, feces should be processed as soon after passage from the
animal as possible.
- Feces should be collected in airtight containers to prevent
desiccation.
- If the processing of a fecal specimen must be delayed, it may be:
- refrigerated (but not frozen) for several days ( not recommended for samples with live larvae that you
intend to examine using the Baermann technique).
- fixed, e.g., 10% formalin (5% formalin-saline is
better for protozoal cysts). Add fixative to feces at a ratio 3:1 (v:v) and mix
well. (Not for Baermann technique.)
- If an animal has been treated with anti-diarrhea preparations containing bismuth or kaolin, mineral oil, oral contrast material (barium) for radiology (all of these materials float) or antibiotics, then parasites may be difficult or impossible to find. Therefore, repeat the fecal exam 5-10 days after treatment withdrawal.
Processing
- First, examine the feces for blood and other clinical signs, then examine the inside
of container for tapeworm segments (which are motile and may move away from the fecal
mass).
- Many techniques have been devised to increase the likelihood that parasites will be
detected in a particular sample of feces. The merits and limitations of representative
fecal processing techniques are summarized in the table on the next page. Step-by-step
directions for performing the various methods are on the following pages.
Repeat Fecal Exams are suggested in the following situations:
- Clinical signs suggest parasitism, but initial fecal exam was negative. Repeat in 2
or 3 days. Repeat for a total of 3 times within 7 to 10 days, if no parasites are seen it
is likely the animal is not infected.
- Following specific therapy of a parasitic infection, have owner submit a fecal
specimen 2 weeks following the last administration of drug. (This is late enough that all
eggs and cysts will have been cleared from the gut, but , for most parasites, too early
for re-infection to be showing up.)
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