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Collection and Processing of Samples for Parasitology



  • 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.


  • 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:

  1. 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.
  2. 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.)


Copyright © 2006 - University of Pennsylvania School of Veterinary Medicine, All rights reserved.
Faculty: Dr. Thomas Nolan
Students: Molly Church V'09, Diana Knight V'08, Douglas Gilson V'05, Chris Dykhouse V'04, Kimberly Mah V'00

Comments or Questions contact Dr. Tom Nolan at: