North American Veterinary Licensing Examination (NAVLE) Practice Test

The primary differential diagnosis in this case is granulomatous meningoencephalitis (GME), which is a common neurological condition in dogs, particularly in certain breeds like terriers. GME is characterized by inflammation of the central nervous system (CNS) and typically presents with a variety of neurological signs, including head tilt, ataxia, and nystagmus, similar to what is described for the Rat Terrier patient.

The combination of right head tilt and left-sided hypermetria suggests a dysfunction in the vestibular system or the proprioceptive pathways that involve the cerebellum, which aligns with GME. Vertical nystagmus further indicates a central vestibular issue, which is consistent with the lesions seen in granulomatous meningoencephalitis.

This condition is marked by a chronic inflammatory process that can affect the brain and spinal cord, leading to the neurological signs observed. The age of the dog and the breed predisposition also support GME as the most likely diagnosis in this case.

In contrast, other conditions such as fibrocartilaginous embolism (FCE) often present acutely and are less likely to produce the combination of signs described. Central pontine myelinolysis is rare in