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Animal Health Diagnostic Center -
Emerging Issues
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Canine Influenza Virus
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 Detection |
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| For a printable copy, please view the PDF version (134 KB) of this
announcement. The Animal Health Diagnostic Center at Cornell has conclusive evidence that canine influenza virus
is now present in the New York City area. Reports have been received indicating that an unusual form of
“kennel cough” has been seen in a number of veterinary practices. Animals recovering from this clinical
presentation that have been tested are all serologically positive for canine influenza virus. Acute and
convalescent sera from several dogs showed a positive response to canine influenza virus over the course
of the illness. Tests of selected New York State dogs last year were all negative.
Canine influenza virus is a relatively new pathogen of dogs. It was first identified in racing greyhounds
in 2004 and this virus appears to have been involved with significant respiratory problems on the dog tracks
throughout the U.S. for the last 2-3 years. The Virology Lab at Cornell isolated the first influenza virus
from an animal that died during one of these clinical episodes. Evidence of infection of non-greyhounds
by influenza virus has been found in Florida that spring as part of the ongoing research efforts by Dr.
Cynda Crawford at the University of Florida on respiratory disease in dogs. We confirmed this finding
using samples from an animal shelter in the Miami area. <more>
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| Appropriate Samples for Detection |
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For a printable copy, please view the PDF version (142 KB) of this
announcement.
As with most viral diseases, there are several ways to determine the role of a virus in a clinical event.
While there is a tendency to want a single sample type that will work in all cases, the reality is that this
is not possible. The list of possible tests is:
1. At present the most reliable way to diagnose canine influenza virus infections is by
serological tests. The direct link between canine influenza virus and a clinical event is through the
collection of acute and convalescent serum samples. First sample is collected at the first presentation
of the patient and then 2-3 weeks later. Serum can be separated from the clot and held in the refrigerator
until collection of the second sample. Samples can be shipped overnight without cold packs or 2-day delivery
with cold packs. For animals that have recovered from a case of “kennel cough”, a single serum
sample can determine whether the animal has been infected with canine influenza virus at some point in the
past. As this is a relatively new pathogen of dogs, we do not expect to find a high seroprevalence in
unaffected dogs.
Go to Canine Influenza Virus HI for test fee and submission-related information.
2. At present , the most reliable way to directly detect the virus is through a PCR test on either
swabs (nasal swabs preferred) or respiratory tissue. A generic PCR test that detects the highly conserved
matrix gene is the test of choice. While we are currently looking for the H3N8 virus, a test unique to
this virus would miss a potential influenza infection caused by another flu strain such as H5N1. Broad
screening tests are to be used whenever possible in surveillance programs.
Go to Influenza Virus Matrix PCR for test fee and submission-related information.
3. Isolation of canine influenza virus is a relatively unreliable way to confirm the infection.
The reason for this is not clear, but the timing of the sample collection may be the main culprit.
Experimental infections have shown that nasal swabs are nearly twice as successful in isolating the
virus as nasopharyngeal swabs taken at the same time on the same animal. We continue to encourage the
submission of samples for virus isolation because it is essential to track the genetic changes that are
occurring in the virus as it makes its way through the dog population. Samples that are submitted for PCR
detection of the virus that are test positive, will be automatically set for virus isolation at no addition
cost.
NOTE: All dogs that cough are not infected with canine influenza virus. The standard respiratory
pathogens of dogs have not gone away. One should always consider a complete diagnostic work-up that would
include cultures for bacteria and mycoplasma. Check our fee manual for sample submission information and fees.
Submission forms for the AHDC can be downloaded from
the Sample Submission Requirements section of the
Testing Services webpages. |
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