North American Veterinary Licensing Examination (NAVLE) Practice Test

The presumed diagnosis for a calf that has aborted with petechial hemorrhages and lymphadenopathy aligns with the Foothill abortion agent. This condition is commonly associated with the occurrence of abortions in cattle, particularly in specific geographic areas often referred to as foothill regions. The presence of petechial hemorrhages indicates a potential infectious cause that disrupts the normal blood supply or causes localized clotting issues, which are features noted in infections associated with this agent.

Additionally, lymphadenopathy, which is the enlargement of lymph nodes, supports the idea of an infectious agent affecting the immune system. Foothill abortion, also known as "Foothill abortion disease," is linked with a specific bacteria within the region and has well-documented signs including these clinical manifestations.

While the other conditions listed can also lead to abortion in cattle, they typically have different presentations or additional clinical signs that are not outlined in the details provided. For instance, Leptospira pomona can cause reproductive issues along with systemic signs, while Neospora caninum usually presents with different neurological or reproductive abnormalities. Brucella abortus is primarily characterized by retained placenta and chronic infectious conditions rather than the acute symptoms described. Thus, the specific symptoms of petechial