Respiratory tract disease is a common problem that presents during the summer months. It is often inflammatory in origin affecting lower or upper (or both) airways. Lower airway disease is commonly referred to as “Recurrent airway obstruction” (ROA) and upper airway disease as “Inflammatory airway disease” (IAD). Horses show variable signs including coughing, nasal discharge, increased respiratory effort, lethargy and exercise intolerance. Lower airway disease tends to be more severe than upper. Both ROA and IAD represent a spectrum of chronic inflammatory disease of the airways which resembles human asthma in many respects. Many people now refer to the term “Equine asthma syndrome” to describe the presentation of ROA and IAD.
The inciting cause is thought to be environmental whereby aerosolized allergens such as dust, fungi, molds, endotoxin, ultrafine particles, microorganisms, mite debris, vegetative material, inorganic dust and noxious gases enter the airway and set off an inflammatory reaction. There is currently no evidence to support a bacterial or viral infection relationship with inflammatory airway disease.
Management of this syndrome is based on clinical exam findings and will typically include corticosteroids and possibly antibiotics. This is dependent on the severity of the findings including the grade of tracheal mucus seen via endoscopy.
There is good evidence to show that reduced exposure to airborne dust can improve clinical signs. This is done by using “low dust” feed stuff and bedding and by improving ventilation if horses are housed in doors. Many horses in the Tauranga region are housed at pasture and modification of the environment can prove difficult. However, some things can still be attempted such as wetting hay, shifting to different paddocks or areas or by changing feedstuff. In some cases long term therapy with inhalers is required to continuously manage the syndrome. Mild cases are typically manageable but cases can progress in severity and become a recurrent problem.
For further advice or if you have any horses with suspected symptoms please contact one of our large animal/equine vets.
Marcus Allan BSC BBSC