Development and Resolution of Pulmonary Arterial Hypertension in RAO Horses T

Type of Document Master's Thesis
Author Martin, Robert Brian
URN etd-10132003-155036
Title Development and Resolution of Pulmonary Arterial Hypertension in RAO Horses
Degree Master of Science
Department Veterinary Medical Sciences
Advisory Committee
Advisor Name Title
Virginia Buechner-Maxwell Committee Chair
Jonathan Abbott Committee Member
Lydia Donaldson Committee Member
Richard Broadstone Committee Member
Yong-Hoon Lee Committee Member
Keywords

* Pulmonary arterial pressure
* Hypertension
* Horse
* RAO

Date of Defense 2003-08-12
Availability unrestricted
Abstract

TITLE

DEVELOPMENT AND RESOLUTION OF PULMONARY ARTERIAL HYPERTENSION IN RAO HORSES

Robert B. Martin

Craig Thatcher, LACS Chairman

(ABSTRACT)

Equine recurrent airway obstruction (RAO) is associated with airway inflammation and bronchoconstriction in clinically affected horses. Horses demonstrating severe pulmonary compromise develop concurrent secondary pulmonary hypertension. The development of pulmonary hypertension is well documented in RAO affected horses, however, it is not known how rapidly increases in pulmonary artery pressure occur after the onset of RAO. It is also not known if pulmonary hypertension resolves concurrently with resolution of RAO. The goal of this study was to measure pulmonary artery pressure in RAO affected horses during the development and resolution of RAO. To accomplish this, three RAO affected and three normal horses were placed in a challenge environment where clinical parameters, pulmonary function, right heart and pulmonary artery pressures were measured on day 1, 3 and 5. After evaluating horses on day five, their environment was modified to reduce exposure to respirable debris and anti-inflammatory medication (dexamethasone) was initiated. Identical clinical parameters were measured on days 7 and 9. In our study, the arterial oxygen content in RAO horses was significantly less that that of control horses from day 1 through day 9. A concurrent increase in pulmonary artery pressure also developed on day 3 in RAO affected horses, and persisted through day 5. While some trend towards a difference between groups was noted, no other significant differences were observed between RAO and normal horses. These findings suggest that horses with severe RAO also develop significant increase in pulmonary artery pressure, which rapidly resolves with appropriate management of RAO.

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