OCTOBER 2023 VOLUME 32, NO.4
A PUBLICATION BY: THE UNIVERSITY OF KENTUCKY DEPARTMENT OF VETERINARY SCIENCE, MAXWELL H. GLUCK EQUINE RESEARCH CENTER FUNDED BY: EQUUS / STANDARDBRED STATION, INC. M&J INSURANCE
IN THIS ISSUE
R E SE A R C H SPOTLIGHT
INTERNATIONAL
The impact of short-term transportation stress Third Quarter 2023 P. 2,3 on endocrine and immune function in horses. Recent advances in lameHorses are routinely transported for equestrian ness detection and localization in the horse P.4,5 events as well as medical care. It is well recognized that long-distance transportation is a risk factor NATIONAL for the development of pleuropneumonia. Results Equine neuroaxonal from a nationwide survey showed that horses dystrophy / equine deare most commonly trailered short distances of generative myeloencephalopathy P. 5,6 three hours or less. The Adams Lab at the Gluck Equine Research Center within the University of NATIONAL/KENTUCKY Kentucky Martin-Gatton College of Agriculture, Why do we need genomes Food and Environment is currently working to and how do we use them? P.7 investigate the impact of acute transportation stress on immune function in different groups of horses. Previous research has shown that T H ANK YOU S PON SO RS! transporting horses one to three hours can elicit a stress response as seen through increased heart rate. Our lab has previously shown that shortterm transportation stress can cause changes in whole blood gene expression of cytokines in aged horses. Following these findings, we wanted to know if similar responses occur in young horses. Additionally, since horses are often transported to veterinary clinics for diagnostic testing, we have investigated the effect of transportation on endocrine responses and testing for insulin dysregulation. Two studies where horses were transported one and one-half hours (55 miles) round trip were performed. Study #1 focused on evaluating age-differences in stress and immune response following short-term transportation. Horses were grouped by age with six horses in each group. Group one had an average age of two years old and group two an average age of 22 years old.
Study #2 evaluated differences in endocrine responses to transportation between seven insulin dysregulated (ID) and seven age-matched noninsulin dysregulated (non-ID) horses. For both studies blood, saliva, heart rate and temperature were collected before and after transportation. Transportation stress led to various physiological changes in both studies. For both studies, heart rate and cortisol increased in response to transportation, with the highest heart rates recorded at loading and both serum and salivary cortisol being highest directly after transport. There were no differences based on age or whether a horse was insulin dysregulated. In Study #1, all horses had increased ACTH following transportation, with three out of five aged horses having ACTH concentrations above the cutoff for pituitary pars intermedia dysfunction (PPID) 15 minutes after transportation. While rectal temperature was not influenced by short-term transportation stress in either study, these studies were conducted in mild weather during the spring and fall. Study #1 also showed increased gene expression of the pro-inflammatory cytokine IL-6 posttransport in aged horses and increased salivary IL-6 in aged horses compared to young horses. Additionally, aged horses had increased cytokine production from lymphocytes compared with young horses. These results are all indicative of the older horses being in a state of “inflamm-aging” where they have increased inflammatory markers, putting them at higher risk for development of diseases. Serum insulin was measured in both studies. In Study 1, insulin was increased one to three hours post-transportation in aged horses and followed a similar trend in ID horses in Study #2,
OCTOBER 2023 | 1