Researchers in the United States and Denmark have found that refrigeration is the best means of storing horse dung while waiting to carry out a faecal egg count.
The researchers also found that accurate results can be obtained from faecal samples collected from the ground within 12 hours of passage from the horse’s gut.
The study will be published in an upcoming Veterinary Parasitology journal.
“Faecal analyses are becoming increasingly important for equine establishments as a means of parasite surveillance and detection of anthelmintic resistance,” the researchers, led by Dr Martin Nielsen, noted.
“Although several studies have evaluated various egg-counting techniques, little is known about the quantitative effects of pre-analytic factors such as collection and storage of faecal samples.”
The researchers evaluated the effects of storage temperature, storage time and airtight versus open-air storage on faecal egg counts in a series of experiements carried out in Copenhagen, Denmark, and Athens, Georgia.
They found that, at both locations, samples kept in the refrigerator showed no decline in egg counts, whereas storage in the freezer and incubator led to significantly declining egg numbers during the study.
“In contrast, storage at room temperature yielded marked differences between the two study locations: egg counts remained stable in the US study, whereas the Danish study revealed a significant decline after 24 hours.
“The Danish study showed no differences between airtight and open-air storage and no changes over time, while the US study found a significant decline for open-air storage after 12 hours.
“This difference was attributed to the different barn temperatures in the two studies.”
The authors said that, to their knowledge, theirs is the first study to evaluate the pre-analytic factors affecting egg counts in horses using an experimental protocol in two contrasting geographic and climatic locations.
“Our results demonstrate that refrigeration is the best method for storage of faecal samples intended for egg count analysis, but that accurate results can be derived from faecal samples collected from the ground within 12 hours of passage.”
Effects of fecal collection and storage factors on strongylid egg counts in horses. Nielsen MK, Vidyashankar AN, Andersen UV, Delisi K, Pilegaard K, Kaplan RM. Vet Parasitol. 2009 Sep 30.