North American Veterinary Licensing Examination (NAVLE) Practice Test

The cardinal sign of trigeminal neuritis in affected animals is indeed the inability to close the mouth. Trigeminal neuritis is characterized by inflammation of the trigeminal nerve, which is responsible for sensation in the face and motor functions such as chewing. When this nerve is affected, it leads to a profound loss of muscle function in the jaw, resulting in the inability to close the mouth properly. Animals may exhibit an open-mouth stance, and they may struggle to eat or drink due to this inability.

The other options describe conditions that may be associated with other neurological or muscular issues but are not specific to trigeminal neuritis. Masseter muscle pain is related to dental issues or other types of muscle injury, while circumventing and head tilt are more indicative of vestibular disease rather than trigeminal nerve dysfunction. Dysphagia and stridor can be present in various conditions affecting the throat or laryngeal area but do not directly relate to the specific signs of trigeminal neuritis. Therefore, the inability to close the mouth is a defining characteristic of this condition.