Precision of cyathostomin luminal worm counts: Investigation of storage duration and fixative.
Abstract: Essentially all grazing horses are infected with cyathostomin parasites. Adult cyathostomins reside in the large intestine of the horse and larval stages encyst within intestinal mucosa. Manual worm collection from aliquots of intestinal content is the current gold standard for retrieval and enumeration of luminal parasites, however, no research has been conducted to standardize specific parameters for processing and storage of samples. The aims of this study were (1) to evaluate the precision of current standard operating procedures for enumeration of luminal adult cyathostomin populations, (2) investigate the influence of chosen fixative, either 70 % ethanol or 10 % buffered formalin, as well as storage duration, immediately post necropsy vs. stored for eight weeks, on the magnitude and precision of worm counts, and (3) compare the luminal count magnitude between the three intestinal segments (cecum, ventral colon, dorsal colon). Ten miniature horses were enrolled in this study for euthanasia and necropsy over a four-week period. Luminal worm counts were conducted for 2 % aliquots of the cecum, ventral colon, and dorsal colon and samples were allocated to the two fixatives and the two storage durations. Precision was evaluated by coefficient of variation (CV) and was 13.04 % for total cyathostomin counts. Mean CV for large intestinal segments ranged from 15.31 % to 52.50 % irrespective of fixative used or storage duration. cecum worm counts were significantly lower compared to the ventral colon (p = 0.008) and dorsal colon (p = 0.01). Fixative and storage duration were not statistically associated with count precision or magnitude. This study demonstrated moderate to high precision estimates for luminal cyathostomin worm counts but did not identify any effects of fixative and storage duration within the framework of the study. This is the first study to determine cyathostomin worm count precision, and results will be useful for power analyses in the future.
Copyright © 2022 Elsevier B.V. All rights reserved.
Publication Date: 2022-07-30 PubMed ID: 35930933DOI: 10.1016/j.vetpar.2022.109773Google Scholar: Lookup
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Summary
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The research article examines the impact of storage duration and fixatives on the precision of cyathostomin worm counts in horses. The study revealed moderate to high precision estimates of luminal cyathostomin worm counts but found no effects from storage duration or fixatives.
Objective of the Study
- The study primarily aims to evaluate the precision of the standard procedures currently in use for counting the adult cyathostomin populations in the intestinal tract of horses.
- It also seeks to investigate the effect of storage duration and the chosen fixative, either 70 % ethanol or 10 % buffered formalin, on the precision and magnitude of worm counts.
- The third objective of the study is to compare the luminal count magnitude between the three intestinal segments of the horse, namely the cecum, ventral colon, and dorsal colon.
Methodology
- Ten miniature horses were used in this study and they were subjected to euthanasia and necropsy over a four-week period.
- Luminal worm counts were conducted for 2% aliquots of the cecum, ventral colon, and dorsal colon.
- These samples were separated and preserved using the two selected fixatives and stored for two durations – immediately post necropsy and after eight weeks of storage.
Findings of the Study
- Precision was evaluated by the coefficient of variation (CV) and was found to be 13.04 % for total cyathostomin counts.
- Mean CV for segments of the large intestine ranged between 15.31% and 52.50%, regardless of the fixative used or the storage time.
- The study found that worm counts in the cecum were significantly lower when compared to the ventral colon and dorsal colon.
- The study saw no statistical association between the type of fixative, duration of storage, and the precision or magnitude of the worm count.
Significance of the Study
- This research is the first to determine the precision of cyathostomin worm counts, offering valuable data for future power analyses studies.
- The study contributes comprehensive insight into the manual worm collection process from segments of horse intestine, providing a basis for standardization.
- Despite moderate to high precision estimates, the study noted no effects of different fixatives and storage duration on the worm count.
Cite This Article
APA
Smith MA, Carpenter AB, Nielsen MK.
(2022).
Precision of cyathostomin luminal worm counts: Investigation of storage duration and fixative.
Vet Parasitol, 309, 109773.
https://doi.org/10.1016/j.vetpar.2022.109773 Publication
Researcher Affiliations
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA. Electronic address: mackenzie.smith@uky.edu.
- St. George's University, School of Veterinary Medicine, University Centre Grenada, West Indies, Grenada.
- M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
MeSH Terms
- Animals
- Cecum
- Colon
- Feces / parasitology
- Fixatives
- Horse Diseases / parasitology
- Horses
- Intestine, Large / parasitology
- Parasite Egg Count / veterinary
- Strongyle Infections, Equine / parasitology
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