Dogs are unusual among domestic animal
species, because no viral causes of
naturally acquired conjunctivitis in the
absence of systemic or additional ocular
disease manifestations have been reported.
This lack of recognized viral causes of
conjunctivitis in dogs could be attributable
to unidentified unique traits of the
dog or its viral pathogens, or it could be
the result of inadequate investigation.
Viruses are among the most common
infectious agents of conjunctivitis in several
other mammalian species. In these
species, conjunctivitis is associated with
infection by a variety of DNA and RNA
viral families. Viral conjunctivitis may
occur during generalized infection with
concurrent systemic disease or localized
ocular infection not associated with clinically
detectable systemic abnormalities.
Virus-induced conjunctivitis may be
caused by direct virus-mediated effects
during replication in conjunctival epithelium
or vascular endothelium, humoral
and cellular immune-mediated mechanisms,
and secondary bacterial infection.