INDUSTRY ALERT from IDEXX Reference Laboratories: Second confirmed 2011 case of H1N1 influenza virus infection reported in a Southern California domestic cat

March 18, 2011

On March 7, a young cat with chronic recurrent upper respiratory disease tested positive for H1N1 influenza virus on the IDEXX H1N1 Influenza Virus RealPCR™ Test. Coinfections with several respiratory pathogens were also detected on the Feline Upper Respiratory Disease (URD) RealPCR™ Panel.

The 7-month-old, intact female domestic medium hair (DMH) cat had a history of chronic recurrent upper respiratory disease and was treated and responded to antibiotic therapy in December 2010 and January of this year. On representation to Dr. Paul Mickelson at the Small Animal Hospital in Riverside, California, he recommended a Feline URD RealPCR Panel to determine the underlying infectious etiologies of her illness. The owner mentioned that she had been ill with the flu the previous week. The Feline URD RealPCR Panel was positive for H1N1 influenza virus (confirmed at the California Animal Health & Food Safety Laboratory System) as well as for feline herpesvirus type 1 (FHV-1), feline calicivirus and Myocplasma felis. The role the H1N1 virus infection played in this cat’s current episode of illness is unknown, but it is possible she was more susceptible to infection as a result of other chronic respiratory infections. Today, the cat is responding well to treatment with doxycycline.


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 February, IDEXX reported the first confirmed case of H1N1 virus in a 6-year-old, male domestic shorthair (DSH) who was euthanized because of severe respiratory disease after intensive supportive care, including ventilator support. A second cat, a 10-year-old female DSH, from the same household originally responded to supportive therapy but relapsed and was euthanized 8 days after presentation. H1N1 infection was suspected but not confirmed in this cat. The owners of these cats had recovered from the flu the week prior to the cats becoming ill.

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.

Test CodeTest Name and Contents


Upper Respiratory Disease (URD) RealPCR™ Panel—Feline

Bordetella bronchiseptica, Chlamydophila felis, feline calicivirus, feline herpesvirus type 1 (FHV-1), H1N1 influenza virus and Mycoplasma felis RealPCR™ tests


Respiratory Disease (CRD) RealPCR™ Test—Canine

Bordetella bronchiseptica, canine adenovirus type 2, canine distemper virus, canine herpesvirus type 1 (CHV-1), canine influenza virus (H3N8), canine parainfluenza virus, canine respiratory coronavirus (CRCoV), H1N1 influenza virus, Mycoplasma cynos and Streptococcus equi subsp. zooepidemicus RealPCR™ tests


H1N1 Influenza Virus RealPCR™ Test

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. When acquiring a pharyngeal swab, precautions should be taken to prevent patient from biting and/or ingesting part of swab. Collect sample prior to antibiotic administration.

Turnaround time: 1–3 working days

Expert Feedback on Possible H1N1 Influenza Virus Cases When You Need It

Our team of internal medicine specialists is always available for complimentary consultation. Please call 1-888-433-9987, option 4, option 2, if you have questions.