CPD Article | EQUINE
The cranioventral right cranial and middle lung lobes
are more severely affected 11 supporting aspiration or
inhalation of organisms rather than a hematogenous
spread of infectious organisms 11 . The right hemithorax
is more often affected, probably due to the direct
route of the mainstem bronchus 11 .
Polymicrobial infections are common with gram
positive and negative organisms and anaerobic and
aerobic populations present 9 . Commonly isolated
bacteria include: Pasteurella, Streptococcus,
Actinobacillus, Staphylococcus, Klebsiella, E. coli,
Bacteroides and Clostridium 7 . Many of these bacteria
are normally found within the oropharyngeal region 11
with the most commonly isolated bacteria being
Streptococcus zooepidemicus 13 .
Clinical signs
Clinical signs are dependent on the severity and
duration of the disease 11 . Clinical signs can take up to
5 days to develop 6 after long distance travel and daily
rectal temperature monitoring, post travel, will allow
early identification of a sick horse 7 .
Common acute clinical signs include 10 11 :
move or a recumbent patient can be presented 3 10 .
These cases should be carefully differentiated from
those with rhabdomyolysis, laminitis and colic 6 .
Disease of greater than 2 weeks is regarded as
chronic and additional clinical signs noted include 11 :
Intermittent pyrexia
Rapid weight loss
Oedema – sternal and limb
As most of these clinical signs could be associated
with any infectious respiratory condition induced by
travel stress, it would be prudent to isolate affected
animals and implement strict biosecurity measures 18
until a definitive diagnosis can be made 14 . Infectious
and contagious diseases to consider are:
• Equine herpes virus (EHV),
• Equine Influenza (EI) and
• Strangles (Streptococcus equi subspecies equi) 14 .
Based on clinical signs alone, other non- infectious
differential diagnoses to consider and additional
diagnostic tests are 10 :
Pyrexia
Soft moist cough
Nasal discharge: variable - mild to severe; often
mucopurlulent to serosanguineous13
Anorexia
Depression and lethargy
Respiratory changes: tachypnea, shallow breathing,
flared nostrils
Tachycardia
Toxic mucous membranes
• Neoplasia – cytological evaluation of trans tracheal
aspirate (TTA) or thoracocentesis sample, chest
radiographs and ultrasonography;
• Congestive heart failure – jugular distention,
cardiac auscultation for evidence of murmurs and
arrhythmias, ECG/echocardiography;
• Diaphragmatic hernia - history of trauma, chest
radiographs and ultrasonography.
Diagnostic tests
Due to pleural pain, a stiff stilted gait, reluctance to As a nasal discharge and cough are rather non-
specific clinical signs, careful chest auscultation is
• Volume 20 Issue 3 | October 2018 •
35