VMDiva

Influenza viruses are a specific class of virus with assortments of proteins on the surface.  Canine influenza virus (H3N8) acts much like other influenza viruses in that it causes fever and respiratory disease. This influenza can mimic bordetellosis (aka Bordetella bronchiseptica infection, kennel cough, infectious tracheobronchitis). It is most common in groups of densely populated dogs, like seen in shelter situations, and was first recognized in a colony of racing greyhounds in Florida. The incubation period for development of disease is 2 to 5 days and the course of infection is between 2 to 4 weeks. Canine influenza virus is NOT related to Swine Flu (H1N1).

Because this is a relatively new disease, many dogs have little to no immunity to it. Therefore, infection rate is high with up to 80% of dogs developing clinical signs of disease. Some studies indicate 20-50% will naturally clear the infection without any signs of illness. Dogs with signs of infection may present to their veterinarian with fever, coughing, nasal discharge, and lethargy. A vast majority of infected dogs will recover with appropriate supportive treatment (antibiotics, nebulization, etc.). A small percentage (up to 20%) of dogs will get a secondary bacterial pneumonia and supportive care must be more aggressive. Most of these dogs will recover as long as they receive proper care. Dr. Melissa Kennedy, Clinical Virologist at the University of Tennessee College of Veterinary Medicine, states the mortality rate is “less than 10%, probably less than 1%. Most infections are mild and self-limiting.” This information contradicts some news reports of 100% mortality.

The CDC recently released a statement noting upwards to 30 states have confirmed cases of canine influenza. Testing is available at veterinary diagnostic centers but is not widely performed at this time. The CDC reports, “The tests can be performed using respiratory secretions collected at the time of disease onset or using two blood samples; the first collected while the animal is sick and the second 2 to 3 weeks later.” Ask your veterinarian about testing options.

A vaccination has been developed by Intervet Schering-Plough. Dr. Alice Wolf, a well recognized expert in small animal veterinary medicine, notes,”This is a killed virus vaccine that apparently provides non-sterilizing immunity. Information says that it “lessens the frequency and severity of lung lesions, reduces viral shedding, and reduces duration of coughing.” In other words, it does not prevent infection nor does it completely prevent clinical signs of infection.” She notes it is “definitely” not a core vaccination for every dog but also concedes it “maybe something to consider for shelter animals IF there is an outbreak in (the) shelter.” This vaccination will not provide immunity until 2 weeks following the second booster vaccine which can be given 2-4 weeks following the first. Therefore, this vaccine does not confer rapid immunity and is not useful for dogs immediately entering a boarding kennel or shelter situation.

Canine Influenza will most likely spread to the remaining states in the years to come. Diagnosis may become easier but the treatment modalities are similar to those for moderate to severe infections with Bordetella or other respiratory pathogens.  Awareness without panic and sensationalism is key.  Vaccination is not widely accepted in the veterinary community at this time except in areas of crowded canine populations. Vaccinations are being given to dogs who will be boarded in areas of known outbreaks.  It is merely a matter of time before boarding facilities require this vaccination along with Bordetella for admittance. Even in those situations, the efficacy of this vaccination remains to be proven.