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
[email protected]
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
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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 •