Equine Health Update EHU Vol 20 Issue 03 - Page 34

EQUINE | CPD Article Equine Pleuropneumonia Pleuropneumonia is a non - contagious respiratory disease that most commonly occurs in horses after being transported long distances. Horses tend to exhibit clinical signs within 5 days of travel and rapid identification of affected animals is required so that immediate and aggressive therapy can be instituted. Early diagnosis and appropriate therapy will directly affect the case outcome. Dr CA Rademeyer, BVSc, Cert AVP Eq. (Int. Med.) HILLTOPS VETERINARY CLINIC drrademeyer@kern.co.za Risk factors Horses travelling long distances, generally trips greater than 350km are at risk. The risk is further compounded if there are minimal or no rest stops during the journey1. Head postural position during transport a noted contributing factor in the development of pleuropneumonia2 as defective mucocilliary clearance is a direct result of prolonged elevated head position 3 . Therefore transported horses that have had their heads securely tied,limiting head movement, accumulate oronasal secretions4 due to poor drainage. It can take up to 36 hours to completely clear these accumulated secretions 3 . Poor water intake during transport also reduces mucocilliary clearance and allows accumulation of mucopurulent exudate 16 . Strenuous exercise, such as endurance races, prior to travel may result in lower respiratory tract (LRT) contamination with debri and oropharyngeal secretions 4 and may also suppress the immune system 3 . Other predisposing factors 34 are systemic illness, dust or noxious gas exposure, exercise induced pulmonary hemorrhage, esophageal dysphagia or choke, general anesthesia and upper respiratory tract (URT) viral infections 3 4 . Pathogenesis Pleuropneumonia develops with lower airway contamination by oropharyngeal organisms and subsequent spread into the lung parenchyma and pleural space 6 resulting in pneumonia and pleuritis 11 . The lower airway contamination in combination with a suppressed 11 or overwhelmed 3 pulmonary defense mechanisms 13 contributes to the development of pleuropneumonia . Pleural effusion subsequently develops 10 due to an increased permeability of the visceral pleural capillaries as a result of the parenchymal inflammation 11 . Proteins and cells also leak from the vascular space 11 . • Equine Health Update •