A recent study conducted by researchers at Konkuk University in South Korea has revealed distressing evidence of degenerative brain disease in dogs experimentally infected with the SARS-CoV-2 Delta variant. Surprisingly, these dogs did not display any neurologic or respiratory signs of COVID-19, shedding light on the potential long-term effects of the virus.
The study, which was published in the journal Emerging Infectious Diseases, highlights crucial insights into the pathogenesis of the SARS-CoV-2 virus in mammalian species.
Infection Process and Sampling
The research team intranasally infected six female beagle dogs with the SARS-CoV-2 Delta variant, while six other dogs in the experiment remained uninfected. Additionally, three dogs were given a placebo as controls. The team conducted frequent sampling at various time points, including nose-throat, mouth-throat, fecal swabs, and blood samples, to monitor the progression of the infection.
Viral Distribution and Transmission Patterns
Remarkably, the study found that the viral titers were higher in the nasal and oral mucosa of dogs in the contact group compared to the infection group, indicating the role of these entry points in facilitating the virus’s replication. Dogs in the contact group also exhibited more severe inflammatory responses in the trachea and bronchioles, suggesting a higher risk of transmission and pathologic changes in the upper respiratory tract.
SARS-CoV-2 infected Dogs: Brain Involvement and Blood-Brain Barrier
While the infected dogs did not display any neurological signs, SARS-CoV-2 DNA was detected in the brain at specific time points. The study revealed abnormal changes to the blood-brain barrier (BBB), particularly at later stages of infection. These changes allowed the virus to severely damage BBB cells and cross into the brain, leading to pathologic changes consistent with small vessel disease (SVD).
Long-Term Implications and Translational Research
The implications of the study are significant, as it suggests the potential for a COVID-19-like syndrome to develop in affected dogs over an extended period. The observed neuroinflammatory responses in the white matter and lung alveolar septum thickening indicate the multi-organ impact of the SARS-CoV-2 Delta variant in canine models.
According to the researchers, these findings can serve as crucial translational research data, aiding in the interpretation of potential neuropathologic changes that may be observed in humans. This provides a broader perspective on the long-term consequences of COVID-19 and emphasizes the importance of understanding the virus’s impact beyond the respiratory system.
The study emphasizes the need for continued research into the long-term effects of SARS-CoV-2 in various animal models, shedding light on the potential complications that might arise in both veterinary and human medicine.