Recommendations for veterinarians evaluating feline cases of H5N1

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Following the Colorado Department of Public Health and Environment’s (CDPHE) report on the 6 feline cases of the highly pathogenic avian influenza (HPAI H5N1) in the state,¹ the department published a guidance document for veterinarians assessing feline cases for HPAI infection. The document details infection prevention and control measures, testing considerations, veterinary staff health monitoring, and additional resources.²

Prevention, control, and testing

Cat owners should exercise caution with letting their companion animals go outside, especially those living close to agricultural communities, Kay Russo, DVM, MAHM, DACPV, from Colorado, advised in a Colorado Public Radio News report.³ She also recommended owners keep their cats indoors more frequently now due to the increased risk of exposure.

In the guidance document, 'Highly pathogenic avian influenza A(H5N1): Guidance for veterinarians assessing HPAI H5N1 in domestic felines,' the CDPHE recommends limiting contact between pets and wild birds, as well as ill livestock and environments potentially contaminated with avian flu.² The Department also recommends feline owners change their clothes and shoes after interacting with animals or birds with unknown health status and before interacting with personal pets.²

For veterinarians specifically, the document advises²:

• Following CDC recommendations for veterinarians when evaluating and handling cats potentially infected with H5N1 HPAI
• Using your clinic’s isolation and patient handling protocols for suspected infectious and/or zoonotic disease cases; including negative airflow when possible, containing and disinfecting all equipment used in treating the patient, and using PPE and limiting staff contact with animals in isolation
• All veterinary staff should change shoes and clothes prior to leaving the clinic to prevent spreading H5N1 to other pets, family members, and the community

“It's really important that the owners [of these cats] and the veterinarians observe utilization of proper PPE because this is, in fact, a zoonotic infection,” emphasized Russo in the report.³

Testing guidance for potentially infected cats

Deceased or severely ill feline patients with neurological symptoms should be evaluated for H5N1 testing, according to the state health department. Moreover, rabies viruses should also be considered in the assessment.²

H5N1 and rabies testing can be conducted at the Colorado State University Veterinary Diagnostic Laboratory (VDL). For influenza virus testing, brain tissue is the preferred sample. Furthermore, the guidance document emphasizes veterinarians conducting testing follow these measures²:

• Wear PPE when collecting specimens, including mask, face shield, and gloves
• For deceased or euthanized animals, submit 1” x 2” section of brain (fresh); additional fees may apply for brain removal for whole carcass submissions
• For live animals, submit nasal swab, ocular swab, urine and whole blood
• Samples should be refrigerated and shipped in an insulated box with ice packs
• Contact the VDL at (970) 297-1281 for questions related to animal testing
• Monitor other cats in contact with symptomatic or positive cats
• Refer owners of suspect/positive cats to the CDPHE for human exposure monitoring

Veterinarians seeking guidance or support on suspected cases should contact the Colorado Department of Agriculture (CDA) and reach the Animal Health Division at 303-869-9130 or via email at animalhealth@state.co.us, per the CDPHE.² Anyone who suspects an HPAI infection or any other reportable disease in domestic animals should also contact the CDA at the above information.

Additionally, veterinarians should consider rabies as a differential diagnosis for neurologic cats.² For help with a rabies risk assessment, local public health departments or the CDPHE should be consulted. The CDPHE can assist veterinary professionals who do not know their local health department.² The department can be emailed at cdphe_zoonoses@state.co.us.

H5N1 symptoms in cats

Domestic or feral cats showing symptoms of feline H5N1 typically experience a rapid or severe illness course of 0 to 10 days, according to Colorado's state health department. Signs include²:

• Progressive respiratory and neurologic clinical signs: dyspnea, tachypnea, altered mentation, seizures, tremors, fever, and death
• Lack of response to supportive therapy or antimicrobial therapy

Cats exhibiting a lack of coordination, inability to stand, reduced energy and appetite, nasal discharge, coughing, sneezing, and/or blindness should also be examined. Felines that have been diagnosed with H5N1 have showed the aforementioned symptoms, according to the CDPH.²

Speaking on the disease’s progression, Russo commented, “It's just remarkable how fast and furious [H5N1] is moving…I hope we can get a handle on it soon,” she said in the Colorado Public Radio News report.³

References

1. Bautista-Alejandre A. 6 cats in Colorado are diagnosed with avian influenza. dvm360. August 16, 2024. Accessed August 16, 2024. https://www.dvm360.com/view/6-cats-in-colorado-are-diagnosed-with-avian-influenza
2. Highly pathogenic avian influenza A(H5N1): Guidance for veterinarians assessing HPAI H5N1 in domestic felines. Colorado Department of Public Health and Environment. Accessed August 15, 2024. https://d3cban8v3q1zt4.cloudfront.net/app/uploads/20240809113317/Guidance-for-Veterinarians-assessing-H5N1-HPAI-in-domestic-felines-2.pdf
3. Daley J. Bird flu cases now detected in domestic cats in Colorado. Colorado Public Radio News. August 12, 2024. Accessed August 15, 2024. https://www.cpr.org/2024/08/12/bird-flu-cases-detected-in-domestic-cats-colorado/