North American Veterinary Licensing Examination (NAVLE) Practice Test

When evaluating a 4-year-old horse that presents with fever and ataxia, equine granulocytic ehrlichiosis should indeed be considered due to the specific clinical signs and the nature of the disease. This condition is caused by the bacterium Anaplasma phagocytophilum, which is transmitted by ticks and results in systemic illness characterized by fever, lethargy, and neurological signs such as ataxia.

The presence of fever indicates an infectious process, while ataxia suggests involvement of the nervous system or significant systemic illness. Equine granulocytic ehrlichiosis can cause a variety of symptoms that correspond with these findings, making it a relevant diagnosis in this scenario. Neurological signs may arise from the inflammatory response or potential central nervous system involvement.

Other options may present with overlapping symptoms, such as strangles (which primarily affects the respiratory tract), pneumonia (common with respiratory signs and fever), or laminitis (often involves lameness rather than fever or systemic signs). However, they do not typically present with ataxia as a common feature, making equine granulocytic ehrlichiosis a more fitting diagnosis in this context.