Transmission among mammals of bovine highly pathogenic avian influenza (HPAI) H5N1 viruses, which have caused outbreaks in US dairy cattle (1–3), has been demonstrated in ferrets by our group (4, 5) and the US Centers for Disease Control and Prevention (CDC) (6). These studies showed that these viruses can be transmitted among ferrets via respiratory droplets, albeit with lower efficiency than seasonal human influenza viruses. In contrast, bovine HPAI H5N1 viruses spread easily among ferrets through direct contact (3 of 3 [100%] ferrets) (6). Although ferrets are frequently used for influenza virus transmission (7–9) and vaccine efficacy (10, 11) studies, they demand considerable housing space and personnel and can be difficult to handle. Here, we investigated the transmissibility of the bovine HPAI H5N1 virus A/Texas/37/2024 (TX/37), which was 100% lethal in ferrets inoculated with as little as 10 plaque-forming units (PFUs) (5) by using a hamster model. Six-week-old Syrian hamsters were anesthetized and intranasally infected with 103 PFU of TX/37. To study respiratory droplet transmission, we placed an infected animal in one chamber of a transmission cage that had two wire mesh partitions 5 cm apart to prevent direct and indirect contact between animals (Fig. 1A) and placed a naïve hamster in the other chamber in 24 h post-infection (four pairs). To study direct contact transmission, we cohoused an infected hamster with a naïve hamster (Fig. 1B) at 24 h post-infection (five pairs). Nasal washes (NWs) with 400 µL of phosphate-buffered saline (PBS) were collected every other day starting on day 2 post-infection or post-exposure (Fig. 1C), and virus titers were quantified by performing plaque assays in Madin-Darby canine kidney cells. The NW of the exposed hamsters was also tested by using a rapid diagnostic kit (ESPLINE Influenza A&B-N, FUJIREBIO, Japan), and if positive, the hamsters were euthanized, and their nasal turbinates, lungs, and brains were collected for virus titration.