In a concerning development for veterinary professionals, the highly pathogenic avian influenza (HPAI) H5N1 virus has been detected in multiple mammalian species, including domestic cats, dairy cattle, and wildlife. Recent findings from Colorado and a groundbreaking study from Cornell University highlight the evolving nature of this virus and its potential implications for animal and public health.
Colorado health officials have reported six feline cases of HPAI H5N1 in 2024, with varying exposure histories. One case had a link to an infected commercial dairy facility, while two were indoor-only cats with no direct exposure. Three cases involved indoor/outdoor cats known to hunt small prey. The clinical presentation typically began with lethargy and inappetence, progressing to respiratory and neurological signs. Notably, the neurological symptoms were often indistinguishable from rabies, emphasizing the need for comprehensive diagnostic testing.
The virus strain identified in these cases belongs to the B3.13 lineage of the Eurasian 2.3.4.4b clade, which has shown an unusual ability to spread in non-traditional host species. This particular strain has not been detected in migratory waterfowl, suggesting a shift in transmission patterns.
Corroborating these findings, a study published in Nature by researchers from Cornell University’s College of Veterinary Medicine provides evidence of mammal-to-mammal transmission of HPAI H5N1. The study documents transmission between cows and from cows to cats and a raccoon. Whole genome sequencing shows cow-to-cow transmission when infected animals moved from Texas to Ohio. Cats, a raccoon, and wild birds on affected farms also contracted the virus, likely through raw milk consumption or environmental contamination.
While the current risk of efficient human infection remains low, Dr. Diego Diel, co-corresponding author of the Cornell study, warns of the potential for mutations that could lead to mammalian adaptation and possible human transmission.
These developments underscore the critical need for veterinary professionals to:
- Consider HPAI H5N1 in differential diagnoses, even when typical risk factors or clinical signs are not present.
- Implement rigorous biosecurity measures in all veterinary settings.
- Educate pet owners about potential risks and preventive measures.
- Engage in early testing and report suspicious cases.
- Stay informed about the evolving situation and updated guidelines from health authorities.
The HPAI H5N1 in domestic cats is a threat and the virus continues to adapt and spread. The veterinary community has to play a crucial role in surveillance, containment, and public health protection. Continued vigilance and collaboration between animal and human health sectors will be essential in managing this emerging threat.
www.colovma.org/cvma-news/influenza-a-highly-pathogenic-avian-influenza-h5n1-in-domestic-cats/
