By Brenda Goodman and Nadia Kounang, CNN (CNN) — In early March, Dr. Barb Petersen, a large-animal vet in Texas, began getting calls from the dairy farms she works with in the Panhandle. Workers there were seeing a lot of cows with mastitis, an infection of the udder. Their milk was thickened and discolored, and it Read this story at KEYT , KIFI
