High Path (H5N1) Influenza Testing in Pets

Two blue gloved hands hold a vial with a barcode on it

How do pets become infected?

Cats and dogs can become infected with H5N1 through a variety of exposure routes:

  • Consumption of unpasteurized milk from infected cattle
  • Preying on infected birds and animals
  • Eating uncooked poultry, eggs, or beef from infected animals
  • Exposure to other animals infected with H5N1
  • Exposure to people who work on affected farms and to their clothing or other fomites

Cats appear to be particularly susceptible to severe illness. The likelihood of dogs catching H5N1 continues to be very low. It is not yet known if H5N1 can be directly transmitted between pets. There is evidence to suggest cat-to-cat transmission in big cats (e.g., tigers), but as of now, not between domestic cats. There is also no known evidence that H5N1 can be transmitted from infected humans to pets. The risk of pets spreading H5N1 to people is considered extremely low, but is not zero. H5N1 is considered low risk to the public, but risk is greater for those who handle and care for infected animals.

What are the clinical signs of H5N1 in pets?

Clinical signs of H5N1 infection in cats are better known than in dogs. Cats (domestic and large felids) in particular can experience severe illness or death from infection with H5N1. While dogs can also contract H5N1, they usually exhibit mild clinical signs and low mortality compared to cats. At present, H5N1 has not been detected in dogs in the United States, but there have been fatal cases in other countries.

Reported clinical signs include anorexia, fever, lethargy, discharge from the eyes and nose, respiratory signs due to pneumonia, neurologic signs due to encephalitis, and death in some cases. However, it is important to note that similar clinical signs are often encountered with common respiratory diseases of cats and dogs.

Criteria for submission that will be paid for by the National Animal Health Laboratory network

The following clinical and history must be met:

1.     The pet must have one or more of the following clinical signs (after other possible etiologies have been ruled out)

  • Acute onset respiratory illness (e.g., dyspnea, tachypnea, oculonasal discharge, thoracic radiographic findings consistent with pneumonia).
  • Neurologic illness (acute and rapidly progressive encephalopathy, ataxia, paralysis, seizures, blindness/chorioretinitis)
  • Lethargy, loss of appetite and fever (especially with neutropenia/leukopenia, thrombocytopenia, and/or hepatopathy

and

2.     A history of one of the following within the 2 weeks preceding onset of the present illness:

  • Consumption of raw milk, raw meat/egg or raw pet food
  • Hunting and/or consumption of wild birds or poultry
  • Close proximity to or direct contact with dairy farms or poultry farms with H5 detection
  • Lives in the same household or have frequent contact with a pet presumptive or confirmed H5 infection

H5N1 testing in pets at the UMN VDL

Samples to submit from a live animal: 

  • In cats, oropharyngeal swabs have proven to be the most reliable samples for testing; nasal swabs would also be suitable
    • Use a sterile swab to obtain a sample of saliva and/or secretions from the area around the pharyngeal folds
  • In dogs, nasal swabs and oropharyngeal swabs are suitable; nasal swabs are preferred
  • Submitting swabs for PCR testing
    • Sterile polyester swabs (Dacron or Rayon) with a plastic shaft are recommended
    • For transport, place the swab in a plain, leakproof, sterile container, such as a snap cap tube or red top tube. Trim the swab shaft short enough for the lid to securely close.
    • Transport media is not required
      • If using transport media, please label the tube with the solution type and volume (e.g., 1 swab in 2 mL of 1x PBS)
      • Do not use agar gel-type media or media with additives (e.g., charcoal, antibiotics, heparin)
    • Samples should be refrigerated and shipped in an insulated box with ice packs

For deceased or euthanized cats or dogs with suspected H5N1, please submit the whole animal.

  • Rabies must be considered as a differential diagnosis for any cat or dog presenting with neurologic signs.

Samples will be screened for influenza A virus using the IAV matrix gene detection PCR. The result is reported as either negative or non-negative, as the National Veterinary Services Laboratory (NVSL) must perform an additional confirmatory test on any non-negative result for a domestic animal to be considered positive for H5N1. Further characterization of the virus strain would also be performed by the NVSL.

Relevant test fees

  • Rabies extraction/preparation: $22.00 per animal
    • For cats only, H5N1 testing (CNS) may be added with no charge for submitter
  • Influenza A virus matrix real-time PCR (performed at St. Paul facility): $38.50 each test
  • Necropsy/general exam of tissue, canine/feline: $320.00 per animal
  • Accession fee per submitted case: $10
  • 10% out-of-state surcharge when submitting vet and owner are located outside of MN
  • The National Animal Health Laboratory Network (NAHLN) may cover the cost of Influenza A testing in some cases:
    • Live cats/dogs with clinical signs
    • Deceased cats/dogs with neurological signs where rabies has been ruled out
    • Pets with known exposure to H5N1 
    • Please refer to “Criteria for submission that will be paid for by the National Animal Health Laboratory network” above
    • Any positive samples will be forwarded to the National Veterinary Services Laboratory (NVSL) for confirmation (testing costs covered by NAHLN)

References