Questions about transmission and clinical disease in cows need to be answered before vaccine development takes shape.
The country had reported sporadic H5N5 detections in wild birds in mammals in 2023.
Along with multiple detections now in dairy cows, avian flu has also hit 2 massive farms housing egg-laying hens in the state.
The CDC said H9N2 is the most commonly identified avian flu virus in Vietnam.
Today's announcement raises the number of affected states to 8.
Seven states have now reported the virus in dairy herds, with detections at 21 facilities.
The patient lived adjacent to a poultry market, but there were no reports of bird illnesses or deaths.
The virus is a reassortant between the older H5N1 clade (2.3.2.1c), still circulating in parts of Asia, and a newer H5N1 clade (2.3.4.4b) that began circulating globally in 2021.
The outbreak in Texas will prompt the culling of about 1.6 million layer hens, as Michigan marks its fourth outbreak at a commercial farm.
The nasopharyngeal swab didn't suggest upper respiratory involvement, and virus sequencing of the eye sample showed one change that isn't linked to transmission.