Canine Influenza (H3N8)

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Canine Influenzia (H3N8)

In the last weeks of September 2005 and continuing into October, numerous warnings to dog owners about a new lethal canine disease swept the Internet. Some of these warnings contained legitimate information while others contained half-truths or information that is simply wrong. We would like to take this time to sort out the facts from the theories from the misinformation. Here is what we hope is a helpful FAQ regarding this relatively new virus that has come to be considered part of the kennel cough complex.

What is Canine Influenza?

pneumonia results from secondary bacterial infections (i.e., bacteria invading the lung after the virus has damaged the tissue and compromised its ability to defend itself). Pneumonia in dogs is virtually always secondary in this way (meaning that an initial condition damages the lung and allows bacterial invaders to settle in) and treatment is similar regardless of the cause.

One treatment that might be different in this disease compared to other pneumonias or respiratory disease is oseltamivir (Tamiflu). This is an antiviral medication used in treating human influenza and is helpful only if used early in the course of infection or in prevention of infection in exposed dogs.

Can Dogs get Reinfected?

After a dog has recovered from canine influenza, immunity appears to last at least 2 years.

How are Dogs Tested for Canine Influenza?

In a perfect world there would be a simple test that could be performed on a single sample and yield unequivocal results.

There are three main ways to confirm canine influenza infection.

PCR Testing
PCR testing is a method of testing involving amplifying small samples of DNA to make them more easily detectable. A nasal swab is used for the sample but timing is crucial; the sample must be obtained 3 to 4 days after the onset of symptoms. Because timing is difficult, this method is not commonly recommended.

A blood sample is tested for antibodies against canine influenza virus and the antibody level is compared to that from a second sample taken later. The first sample is drawn within one week of the onset of symptoms and the second sample is drawn 2 to 3 weeks later. If the second sample shows a four-fold increase in antibody level, this indicates a true infection has occurred. This means, inconveniently, that diagnosis cannot be confirmed for several weeks after the dog has gotten sick. A single sample with antibodies present only indicates that the dog has been exposed to influenza and does not clarify whether the infection is current, recent or in the long past.

Negative test results are not felt to rule out a diagnosis of canine influenza infection.

ELISA test kits are available to detect human flu virus in a matter of minutes at the doctor’s office. These kits will also work to detect canine influenza virus in a canine nasal swab. False negatives may be a problem but a positive result can be trusted. Some veterinary offices are using these kits for their coughing canine patients.

Does Vaccination against Kennel Cough (Bordetella) or Parainfluenza Offer any Protection against Canine Influenza?

No. These are all completely different infections; however, there are two canine influenza vaccines that have recently become available (one from Intervet/Schering and the other from Pfizer Animal Health). Vaccination is recommended for dogs that board frequently, attend group training classes or events with other dogs, play regularly at the dog park or doggie daycare, or who go to the groomer consistently. If you think your dog is at risk, talk to your veterinarian about vaccination.

Can People get Infected?

People cannot get infected by this virus. Influenza viruses are specific for their host species and require a dramatic mutation in order to jump species. You should not be concerned about getting an influenza infection from a dog, horse, or any other species other than a fellow human being.


Intervet/Schering-Plough Animal Health has information on the Canine Influenza Vaccine, H3N8.

Please feel free to contact us here at Falls Road Veterinary Hospital with any questions or concerns. (301) 983-8400. www.

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