A case for cold storage

Research shows that the way manure samples are handled can affect the accuracy of fecal egg counts.

A new study suggests that the way manure samples are stored can have a significant impact on the accuracy of fecal egg counts.

Fecal egg counts, which indicate a horse’s parasite burden, are best performed on fresh manure. However, rushing a sample to a laboratory for analysis isn’t always possible, so researchers at the University of Sheffield set out to compare the effects of commonly used storage techniques on the eggs in manure.

For two weeks, one group of manure samples was stored using high and low concentrations of chemical fixatives, such as ethanol and formalin, that are commonly used for preservation in laboratories. At the same time, another group of manure samples was placed in a refrigerator. The number of eggs in each sample was counted at the beginning and at the end of the storage period.

The data showed a significant decrease in egg counts in manure stored in both high- and low-concentration fixatives while counts in refrigerated samples remained stable for eight days. Exactly how long a sample can be refrigerated without affecting egg counts is unclear, but the researchers recommend storing samples for no longer than a week before testing.

Reference: “Testing storage methods of faecal samples for subsequent measurement of helminth egg numbers in the domestic horse,” Veterinary Parasitology, May 2016

This article first appeared in EQUUS issue #469, October 2016.