How to Maximize your Canine Influenza Diagnostic Testing

By Dr. William Fortney

Canine Influenza is a highly contagious viral respiratory disease that affects thousands of dogs annually. Since the respiratory symptoms for canine influenza viral (CIV) infections are not specific, a confirmatory diagnostic sample would be appropriate to definitively rule-in CIV or one of the other canine infectious respiratory agents.

At present the most reliable way to diagnose canine influenza virus infections is by serological (CVI HI) testing. However, because of possible previous exposure to CIV infections and/or a CIV vaccination, an accurate test requires two blood samples. The first sample needs to be collected during the initial illness and the second sample 2-3 weeks later.

Because of the time constraints when using the serology test, PCR completed on a deep nasal swab is considered by most experts to be the preferred sample for diagnosing ACUTE canine influenza. Unfortunately for several reasons, it is relatively common for the PCR test to produce a false negative result (although the dog is infected, the test is negative). Factors effecting the accuracy of the PCR testing results includes:sampling collection timing, sample collection type and media, sampling location, transportation of the sample to the laboratory, and test selection.

The following tables provide guidance to increase the probability of a correct canine influenza virus diagnosis.

Sample collection timingWhile a dog with canine influenza virus may remain contagious for up to 30 days, early sampling significantly increases the chance of a positive CIV PCR diagnosis.




< 24 hours after the first clinical signs

> 24 hours to < 48 hours after the first clinical signs

> 48 hours after the

first clinical signs

Sample collection type and media



Copan-Eswabâ„¢ system

Gel bacterial swab / or bacterial media

Viral swab in viral transport media

Cotton swabs

Viral swab in 0.25 ml sterile saline

Wood handle swabs

Sampling location




Deep nasal swab

Oropharyngeal swab

Superficial nasal swab

Deep sampling of both nostrils (with the same swab)

Deep sampling of one nostril

Transportation to KSVDL




Overnight on ice

2 day shipped on ice


Canine Influenza Virus Test Requested


Fair to Poor

PCR: false negatives can result

Virus Isolation: false negatives are common &

relatively long turnaround time

HI serology: requires two samples,

2-3 weeks apart

The Kansas State Veterinary Diagnostic Laboratory (KSVDL) offers an influenza virus test as part of the Canine Respiratory Diagnostic Panel (LAD-3400) that detects nine different respiratory pathogens including both canine influenza viruses.

For more information please visit the KSVDL website at and check on tests and fees or contact KSVDL Client Care at 866-512-5650

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