North American Veterinary Licensing Examination (NAVLE) Practice Test

For an animal affected by idiopathic trigeminal neuritis, which of the following would you expect to observe physically?

1. Paralyzed eyelids

2. Inability to close the mouth

3. Pain on palpation of the masseter muscles

4. Normal reflexes in the facial region

The correct answer is: Inability to close the mouth

In a case of idiopathic trigeminal neuritis, the condition primarily affects the trigeminal nerve, which is responsible for sensation in the face and motor functions such as chewing. A significant physical manifestation of this disorder is the inability to close the mouth. This occurs because the muscles responsible for this action (particularly those innervated by the mandibular branch of the trigeminal nerve) become weak or paralyzed due to the nerve dysfunction. The inability to close the mouth can lead to difficulties in eating and potentially result in the animal drooling or having a lower jaw that hangs slightly open. While altered facial reflexes and other symptoms may be present, the hallmark of this condition is the compromised ability to close the mouth effectively. In contrast, features like paralyzed eyelids or pain on palpation of the masseter muscles are not typical findings in idiopathic trigeminal neuritis. Normal reflexes in the facial region would usually not align with a diagnosis of trigeminal neuritis, given that this condition affects the sensory and motor functions of the affected area.