Dropped Jaw (Trigeminal Neuropathy) in Cats

The severity of trigeminal neuropathy depends on how severe the impact on the cranial nerve is, and how long the condition takes to run its course. Since the ability to eat and drink is compromised, there is a risk of significant weight loss and dehydration without supportive strategies in place to maintain caloric and fluid intake.

In some cases, trigeminal neuropathy is accompanied by other nerve dysfunctions in the face, including:

• Horner’s syndrome (nerve dysfunction of the eyes)
• Weakness of other facial muscles
• Decreased facial sensation

Trigeminal neuropathy is a very rare disorder in cats and is not life-threatening. Cats with a sudden inability to close their mouths require prompt veterinary attention to prevent dehydration and weight loss. This condition affects all breeds, genders, and ages equally.

Since dysfunction of the jaw impedes the ease of eating, supportive treatment is important to prevent weight loss.

The underlying causes of trigeminal neuropathy are not yet fully understood. For unknown reasons, there is disruption to the signals from the brain to the trigeminal nerve, which is the cranial nerve that controls the jaw. This may be due to injury, inflammation, or degeneration of the nerve. Without appropriate information from the brain, the jaw hangs open, causing difficulties with eating and drinking.

In some cases, the nerve damage may be related to an unusual immune system response to infectious agents or cancer.

The characteristic symptom is a dropped jaw.

Diagnosis of trigeminal neuropathy is challenging to confirm, and relies heavily on the characteristic symptom of a dropped jaw and the ruling out other possible conditions. Diagnostic tools include:

• Physical examination
• Bloodwork
• Urinalysis
• Diagnostic imaging, including X-rays and MRI
• Bone marrow biopsy
• Muscle biopsy

There are no specific therapies to control trigeminal neuropathy. The condition is self-limiting and usually runs its course in 2 to 4 weeks. Severe cases may take as long as 10 weeks to recover.

While symptoms are present, supportive therapies are necessary to maintain caloric and fluid intake. Strategies include:

• Providing water and pureed food via syringe in the corner of the mouth
• Intravenous fluids and feeding tubes
• In cases where supportive care cannot be administered at home, supportive care in hospital may be required

Trigeminal neuropathy usually runs its course in 2 to 4 weeks. In severe cases, recovery takes as long as 10 weeks. In most cases, the prognosis for full recovery is good. In cases where severe weight loss or dehydration occur, the prognosis is more guarded.

There are no proven preventative measures to avoid trigeminal neuropathy.

Trigeminal neuropathy is extremely rare in cats.

Supportive care