Shedding of the virus by an infected dog begins before the clinical signs are noted and, on average, will last 5 days. The virus is spread by aerosol transmission of respiratory secretions via sneezing or coughing. Direct contact with the respiratory secretions or contact with freshly contaminated surfaces will also serve as a source of exposure.
Being a relatively new virus, most dogs have never been exposed to CIV (canine influenza virus). They therefore lack natural or aquired (from previous exposure or vaccination) immunity to protect them from the virus. Consequently, most dogs exposed to the virus are likely to develop clinical signs of the infection.
Signs of CIV infection typically develop within 2-3 days of virus exposure. The clinical signs of CIV infection are similar but may be more severe to those of 'kennel cough'. Lethargy, anorexia, nasal discharge, low grade fever and a persistant, dry non-productive cough are common clinical manifestions of the illness. Some dogs may develop pneumonia. The presence of secondary bacterial infections can exacerbate the severity of the illness. Cases of severe pneumonia, pulmonary hemorrhage, and death which were noted in early outbreaks of the disease, appear to be uncommon in the pet population.
Treatment is supportive in nature, similar to treatment for 'kennel cough'.
In May 2009 the USDA approved a killed adjuvented whole virus vaccine produced by Intervet. A field trial performed in 700 vaccinated dogs failed to demonstrate any side effects.
Efficacy trials have demonstrated the vaccine to significantly reduce the severity and duration of clinical signs of illness and reduce the amount of and duration of virus shedding. The vaccine will not prevent infection. vaccinated dogs may still show mild clinical signs.