The only person who can protect your herd from Brucellosis is you. When buying cattle, you should insist on vaccination records and recent herd tests from the farm of origin. The seller must be able to prove that the heifers were vaccinated, and the herd of origin tested negative for Brucellosis. Furthermore, the seller should also be able to provide proof of regular negative herd tests. It is always advisable to isolate and test any animals brought into the herd.