Home Health and vet Severe equine asthma (SEA) compromises ability and welfare

Severe equine asthma (SEA) compromises ability and welfare


By Joana Simões and Paula Tilley

Severe equine asthma (SEA) is an important respiratory disease affecting a large number of horses worldwide. This chronic disease induces cough and respiratory distress compromising the animals’ athletic ability and welfare.

A wide variety of diagnostic tests have been described for researching and diagnosing SEA, but not all are commonly available outside of large research or specialized diagnostic centers. Moreover, in routine ambulatory practice the process of decision making is not always easy, especially in more complex medical cases, but its importance is pivotal for individualized patient care. Thus, the aim of this paper is to develop a flow-chart to assist equine practitioners in the process of decision making associated with diagnosing and monitoring SEA.


Decision making consists of gathering quality data in order to correctly assess a situation and determine the best course of action. This process is a fundamental part of medicine and is what enables practitioners to accurately diagnose diseases and select appropriate treatment protocols. Despite severe equine asthma (SEA) being a highly prevalent lower respiratory disease amongst equids, clinicians still struggle with the optimization of routine diagnostic procedures. The use of several ancillary diagnostic tests has been reported for disease identification and monitoring, but many are only suitable for research purposes or lack practicality for everyday use. The aim of this paper is to assist the equine veterinarian in the process of decision making associated with managing SEA-affected patients.
This review will focus on disease diagnosis and monitoring, while also presenting a flow-chart which includes the basic data that the clinician must obtain in order to accurately identify severely asthmatic horses in their everyday routine practice. It is important to note that European and American board-certified specialists on equine internal medicine can provide assistance in the diagnosis and treatment plan of SEA-affected horses.

1. Introduction

Severe equine asthma (SEA) is a chronic insidious respiratory disease which commonly affects mature adult horses [1,2]. Its estimated prevalence in the northern hemisphere is 20%, but the number of affected individuals continues to rise [3,4,5].
The precise immunological pathways of this multifactorial disease are complex and not yet fully understood [6,7,8,9,10,11,12], but it is known that when susceptible individuals are exposed to high concentrations of respirable particles they develop inflammation, bronchospasm and airway hyperreactivity [13,14,15,16]. Consequently these animals develop increased respiratory effort at rest, cough and nasal discharge which, depending on inflammation severity, may impact athletic performance and the horse’s well-being [17,18].
According to the type of inflammatory triggers associated with SEA exacerbation, two major disease phenotypes have been described [1]. The stable-associated SEA mainly involves exposure to organic respirable particles found indoors during the colder months, such as in bedding materials, hay and straw [19,20,21], whilst the pasture-associated SEA occurs in animals kept at pasture during the warmer season due to exposure to pollen [22,23,24].
However, inflammation can be triggered by a large number of molecules with a synergistic effect, such as LPS, pollen, mites, fungi spores, or even plastic particles, which can be found in the horses’ habitat [19,20,21,25,26,27,28]. Because antigen avoidance can be extremely difficult to achieve, affected animals tend to present recurrent episodes of disease exacerbation [29]... To read the complete article you need to be a subscriber