10.6.1 Respiratory infections
Respiratory tract diseases are common in horses, and
one of the most frequent reasons for antimicrobial
administration (Table 10.3). Causes for respiratory
tract diseases are multi-factorial. Recommended treatments
are variable and some references still endorse
the use of broad-spectrum antimicrobials for equine
respiratory tract diseases, even to cover the possibility
of secondary bacterial pneumonia from a primary
viral infection, despite the absence of data supporting
these approaches. It is important for equine clinicians
to remember that most respiratory diseases in horses
are non-infectious or viral and do not require antimicrobial
treatment. Furthermore, secondary bacterial
pneumonia is rare. The use of broad-spectrum antimicrobials for respiratory tract diseases based on
clinical signs alone (e.g. fever, cough, nasal discharge)
can no longer be justified. There are a number of
diagnostic techniques (e.g. trans-tracheal wash, tracheal
aspirate, broncho-alveolar lavage, lung biopsy)
that are simple and safe to perform whereby representative
samples can be obtained for culture and
sensitivity (13). Regardless of the causal agent of a
lower respiratory tract infection, adequate stall rest in
a well-ventilated stable and supportive care, including
good-quality hay and water, are the most important
components of recovery. Exercise during clinical disease
and recovery may worsen the clinical disease. Stall
rest for three weeks after clinical resolution has been
used as guideline for bacterial lower airway diseases.