Clinical characteristics of two companion canines with severe fever with thrombocytopenia syndrome virus (Bandavirus dabieense) in Seoul, Republic of Korea.

Severe fever with thrombocytopenia syndrome virus (SFTSV, Bandavirus dabieense) is an emerging tick-borne zoonotic virus causing severe febrile illness with high fatality rates in humans. While ixodid ticks are the primary vectors, secondary transmission through close contact with infected companion animals has also been reported. We describe the clinical characteristics of SFTSV infection in two companion canines from Seoul, Republic of Korea (ROK). Hematological analysis revealed elevated C-reactive protein (CRP) level, increased immature platelet fraction (IPF), leukopenia, and thrombocytopenia. Radiography and abdominal ultrasonography demonstrated splenomegaly, enlarged sublumbar lymph nodes, partial loss of wall layering, and colonic wall thickening; notably, one canine also developed hemorrhagic diarrhea. SFTSV RNA was detected in whole blood by nested PCR, and genotypes were identified as Sub-genotype B-1 and Genotype F. These observations indicate that canine SFTSV infection can manifest with more diverse and severe clinical features than previously recognized. Splenomegaly and colonic abnormalities may serve as useful diagnostic indicators in canine cases. This report emphasizes the importance of considering SFTSV in canines presenting with systemic inflammatory and gastrointestinal signs, and highlights the need for companion animal-based surveillance within a One Health framework. Further studies are warranted to define the full clinical spectrum and to clarify the epidemiological role of canines in SFTS transmission.