Undergraduate Honors Thesis Projects

Date of Award

2016

Document Type

Honors Paper

Degree Name

Equine Pre-Veterinary/Pre-Graduate Studies-BS

Department

Equine Science

Advisor

Dr. Steffanie Burk

First Committee Member

Dr. Jeffrey Lehman

Second Committee Member

Dr. Margaret Koehler

Keywords

equine parasitology, cortisol, cyathostomes, parasite management, anthelmintic resistance, equine endocrinology

Subject Categories

Animals | Endocrinology | Large or Food Animal and Equine Medicine | Other Animal Sciences | Parasitology | Veterinary Microbiology and Immunobiology | Veterinary Pathology and Pathobiology | Veterinary Preventive Medicine, Epidemiology, and Public Health

Abstract

With an increase in anthelmintic resistance and decreased efficacy of many commercial dewormers, understanding factors that contribute to parasite infestations in horses is integral to their management. The goal of this study was to look at the potential relationship between parasites and stress response by evaluating salivary cortisol levels and cyathostome egg shedding levels. Using a sample size of n = 200 horses from the state of Ohio, fecal and saliva samples were collected from each horse. Fecal egg counts were performed for each horse with a modified Stoll method, and saliva samples were tested with an enzyme-linked immunosorbent assay (ELISA). Questionnaires were generated to gain information about each horse and its management. A total of 23 variables were tested against dichotomized fecal egg count levels using Chi-Square Tests of Independence or Fisher’s Exact Tests for significance. Variables with p < 0.30 were analyzed for association with fecal egg count level with a stepwise multiple logistic regression model. The three variables included in the final logistic regression model were age (p = 0.0002), cortisol level (p = 0.036), pasture mowing frequency (p = 0.025), and turnout (p = 0.0573). These p-values are adjusted for the other variables within the model. Location at the time of sampling (p = 0.818) was also forced into the model to account for a naturally lower cortisol level for those horses who were outside. This study analyzed factors contributing to fecal egg shedding levels, and determined managerial practices that can reduce cyathostome levels in horses.

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