It was a Texas veterinarian who collected samples from dairy farms that confirmed the outbreak of H5N1 bird flu in cattle for the first time. Dr. Barb Petersen monitors more than 40,000 cattle on a dozen farms in the Texas Panhandle. She received reports from farmers of dead birds, ailing cats and sick cows in early March. So far, two people in the U.S. have been confirmed to be infected with H5N1, most recently a Texas dairy worker linked to the cattle outbreak.