Air hygiene and equine respiratory disease

Abstract

Air hygiene and equine respiratory disease byAndrew Clarke THE importance of environmental factors on the welfare of the horse have long been appreciated. Percivall (1853) highlighted this point by introducing his treatise on respiratory disease of the horse as follows: 'No general fact appears better established in hippopathology than the one evidencing that disease is the penalty that nature has attached to the domestication of the horse.' Chronic pulmonary disease (CPD) is one such affliction. Clinically CPD is associated with varying degrees of dyspnoea and double expiratory effort. However, in its initial stages the disease may pass undetected until the horse undertakes heavy exertion, as in racing. This article examines those aspects of the air hygiene and the aerobiology of stables as they relate to the pathophysiology and management of CPD in all of its manifestations. Simple guidelines for and practical approaches to the assessment of the air hygiene of stables are described. Aetiology Factors known to be associated with clinically overt cases of CPD include mouldy feeds and beddings, poorly ventilated stables and previous viral and bacterial infections. Subclinical lower airway inflammatory disease has been associated with 'poor performance' of thoroughbreds. Diagnosis of this condition is based on the presence of increased mucopus and inflammatory cells (neutrophils) revealed by endoscopic examination and tracheal washings. Viral infections may predispose horses to succumb to lower respiratory tract inflammation in response to airborne challenges of fungal spores which were of little consequence before infection. Equally larger challenges of fungal spores will induce airway disease in the absence of prior infectious disease. Airborne contaminants of stables Stabled horses are exposed to a myriad of airborne contaminants. These include fungal and actinomycete spore clouds, bacterial and viral aerosols, noxious gases such as ammonia, plant material, dust mites and their metabolites. These contaminants may be pathogenic in a number of ways. They may cause infection, be allergenic, behave as primary irritants or simply 'clog' the respiratory defence mechanism so increasing the system's susceptibility to other pathogens. The sources of and clearance mechanisms for the airborne A #1ii,iie 6heatadetector wt* a o/f/Io(e5c6't7/7g This new concept in heat detection is reliable, reusoble and inexpensive.

Airborne dust and aeroallergen concentrations in different sources of feed and bedding for horses

“…The dust content of wood shavings was, however, lower than that of the good quality hay. But like hay or any materials of plant origin, the microflora of straw and wood shavings can change rapidly when a high moisture content is combined with a high temperature (4,7,16,31). These factors may explain the discrepancy between our results and those previously reported by others (4,6,32).…”

“…In summary, the present investigations (1) propose a standardized method for the assessment of the qualitative and quantitative content of dust in different feeds and bedding; (2) demonstrate that alternative materials may be used to decrease airborne dust and aeroallergen in the immediate equine environment and contribute to the improvement of horse management. (4,28,31), but attention needs to be paid to the horse's feed and bedding, which provide the principal sources of dust in stables (31). In addition, around the horse's nostrils, concentrations of respirable airborne dust are significantly greater than levels measured elsewhere in the stall (32).…”

Recurrent airway obstruction: A review

“…A wide variety of airborne moulds have been identified in equine stables that contain hay and straw , since, if baled with a high moisture content, this herbage is rich in spores of fungi and actinomycetes such as Aspergillus fumigatus, Faenia rectivirgula and Thermoactinomyces vulgaris . In addition to the long‐established observed link between RAO and mouldy hay exposure, several controlled challenge and exposure studies have confirmed this association.…”

Características de manejo y conducta en caballos estabulados en el sur de Chile: Estudio preliminar

“…La utilización de las pesebreras como lugar de almacenamiento de alimento (cuadro 2) no es aconsejable, ya que éste puede atraer roedores que transmiten enfermedades, además el heno en mal estado favorece la presentación de problemas respiratorios como la obstrucción recurrente de las vías aéreas (Clarke 1987, Morán y col 2006.…”