North American Veterinary Licensing Examination (NAVLE) Practice Test

The agent responsible for the symptoms described in the dog, particularly those characterized by vomiting, hemorrhagic diarrhea, and the presence of large fluke eggs in feces following a trip to Oregon, is indeed Neorickettsia helminthoeca. This bacterium is associated with a disease known as salmon poisoning, which primarily affects dogs that have ingested fish infested with the fluke Nanophyetus salmincola.

Neorickettsia helminthoeca is a rickettsial organism that lives within the fluke and is responsible for the clinical signs observed in infected dogs. The clinical presentation of salmon poisoning includes severe gastrointestinal symptoms, such as vomiting and diarrhea, often with a bloody or hemorrhagic character due to the extensive damage caused by the disease process. The association with a trip to Oregon is pertinent because this region is known for its salmon and the potential for dogs to be exposed to infected fish.

While Nanophyetus salmincola is related to the condition and the fluke itself is necessary for the life cycle of Neorickettsia helminthoeca, the rickettsial agent is what causes the clinical disease. Hence, the correct identification of Neorickettsia helminthoeca