First Confirmed 2011 Case of H1N1 Influenza Virus Infection Reported in a Domestic Cat

February 14, 2011

One cat with severe respiratory disease from Wisconsin has tested positive for the H1N1 influenza virus with the IDEXX H1N1 Influenza Virus RealPCRTM Test.

Two cats from the same household presented to a veterinary emergency hospital in respiratory distress. The owners reported to have been suffering from the flu themselves at the time the cats developed severe respiratory signs. After intensive supportive care that included ventilator support, the 6-year-old male domestic shorthair (DSH) was euthanized. The IDEXX Feline Upper Respiratory Disease (URD) RealPCRTM Panel was performed using fluid obtained at the time of intubation for ventilation and was positive for the H1N1 influenza virus. The second cat, a 10-year-old female DSH, originally responded to supportive therapy but relapsed and was euthanized 8 days after presentation. An oropharyngeal swab was obtained at the time of euthanasia for testing, but it was negative for H1N1 influenza virus. Given the strong-positive quantitative real-time PCR result in the first cat, the H1N1 influenza virus is still the presumptive cause of respiratory disease in the second cat. The shedding period of influenza viruses is short, which may have been responsible for the negative PCR result.


From fall 2009 to early 2010 in the United States, there were several reports of H1N1 influenza virus in animals for which the suspected form of contraction was contact with infected people. In response to the concern for HIN1 influenza virus infection in dogs and cats, IDEXX added the H1N1 Influenza Virus RealPCR Test to Feline URD and Canine Respiratory Disease (CRD) RealPCR panels in November 2009. Subsequently, one dog and two cats were confirmed infected by the H1N1 Influenza Virus RealPCR Test and were reported at that time. From January 2010 until now, no additional infections had been detected.

Clinical Signs

The clinical signs of H1N1 virus infection are likely to resemble those of other common respiratory infections; however, more severe respiratory disease, including pneumonia, may be possible. Clinical signs may include:

  • Coughing, sneezing and oculonasal discharge
  • Fever, lethargy and loss of appetite
  • Dyspnea, tachypnea and respiratory distress

When to Test

Testing should be considered in any pet with evidence of respiratory disease. The shedding period of influenza viruses is short. Samples should be submitted for testing within 7 days of the onset of clinical signs to avoid false-negative results in infected animals.

Specimen Requirements

Deep pharyngeal swab (with visible organic material on swab; please rub firmly) and a conjunctival swab (wipe eye clean; swab inside of eyelid) in the same tube. Please submit dry, plastic-stemmed swabs, without transport media, in a serum tube or an empty, sterile tube; keep refrigerated. Collect sample prior to antibiotic administration.

Turnaround time: 1"3 working days

Expert Consultations Available on Possible H1N1 Influenza Virus Cases

Our team of internal medicine specialists is always available for complimentary consultation.


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