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Ask Dr. Michael Salkin Your Own Question
Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Dog Veterinary
Satisfied Customers: 27400
Experience:  University of California at Davis graduate veterinarian with 44 years of experience
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My dog seems to be keeping her mouth pen as if she cannot

Customer Question

My dog seems to be keeping her mouth pen as if she cannot close it. It is causing her to drool especially when she eats or drinks. When she eat or drink she is excessively drooling everywhere. The vet checked her mouth to see if there were any broken or cracked teeth and everything was fine. The vet thought the dog might have hit a nerve but was sure. She sent us home with a week's worth of gabipenten. I am not sure what we should do next.
JA: I'm sorry to hear that. Problems with drinking can be serious. I'm glad you noticed it. The Veterinarian will know what to do. What is the dog's name and age?
Customer: Shiloh and I beleive she is about 6.5 years old.
JA: Is there anything else the Veterinarian should be aware of about Shiloh?
Customer: She freaked out during the fireworks on New Years Eve. That's why the vet thought she may have pulled a nerve trying to dig her way out of her metal crate. However she hasnt really gotten any better so I am not sure if it had anything to do with the fireworks?
Submitted: 4 months ago.
Category: Dog Veterinary
Expert:  Dr. Michael Salkin replied 4 months ago.

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Expert:  Dr. Michael Salkin replied 4 months ago.

I believe that you're describing a trigeminal nerve (cranial nerve V) neuropathy. Please review the following synopsis of this disorder and then return to our conversation with further questions or concerns. The synopsis was designed for vets but you'll get the gist of it.

Definition of trigeminal neuritis/”dropped jaw”

An idiopathic, self-limiting inflammatory condition that involves the motor and sensory branches of the trigeminal nerve and (on occasion) the sympathetic innervation to the eye (i.e., Horner's syndrome).


Dogs most commonly affected; rare in cats

Genetics and Breed Predisposition

No sex or breed predilection; golden retrievers may be overrepresented.

Risk Factors

Other immune-mediated disease

Associated Disorders

Possible paraneoplastic (a cancer elsewhere in the body) association

Clinical Presentation

Bilateral paralysis of the masticatory muscles that primarily affects the mandibular branch of the trigeminal nerve

History, Chief Complaint

Acute or subacute onset of an inability to close the mouth. The dog cannot prehend food, may hypersalivate, and has difficulty drinking water.

Physical Exam Findings

Bilateral paralysis of the masticatory muscles

Affected dogs are bright and alert and do not appear as though they are in pain. Most have no other detectable neurologic abnormalities.

In some cases, there is decreased facial sensation bilaterally, and Horner's syndrome may be observed.

Trismus/inability to open the mouth does not occur with trigeminal neuritis.

Etiology and Pathophysiology

Most common neurologic cause of an inability to close the mouth in the dog

Etiology is unknown, but extensive bilateral nonsuppurative inflammation, demyelination, and, in some cases, axonal degeneration of all portions of the trigeminal nerve and its ganglion, with no brainstem lesions, have been reported at necropsy.

Complete recovery is observed in 2-3 weeks (rarely, may take several months), with no drug therapy being reported as useful.

Facial sensation is usually preserved. Occasionally, Horner's syndrome may be observed, presumably because the postganglionic sympathetic axons course with the ophthalmic branch of the trigeminal nerve.


The diagnosis is based on characteristic clinical signs, absence of other neurologic deficits, and elimination of the possibility of orthopedic (mandibular, temporomandibular joint) disorders. Advanced diagnostic testing is generally reserved for cases showing additional or unusual neurologic deficits, when spontaneous resolution does not occur, or if rabies is possible (quarantine/euthanasia).

Differential Diagnosis


Traumatic mandibular injury

Inflammatory or infectious central nervous system (CNS) disease

Initial Database

CBC, serum chemistry profile, urinalysis: usually within normal limits

Screening for infectious diseases such as protozoal, fungal, and viral diseases is recommended, as clinically and geographically appropriate.

Advanced or Confirmatory Testing

Unnecessary in most cases

Cerebrospinal fluid (CSF) analysis may be normal or show mild increases in protein concentration. Lymphocytic pleocytosis is rarely observed.

Electromyography may reveal increased insertional activity and other mild changes.

Computed tomography or magnetic resonance imaging of the brain: within normal limits

trigeminal nerve biopsy: not recommended


Spontaneous resolution usually occurs in 2-3 weeks with no treatment.

Acute General Treatment

Maintenance of hydration and alimentation is critical.

Percutaneous gastrostomy (a feeding tube) may be helpful in severe cases.

Chronic Treatment

Signs will typically resolve spontaneously in 2-3 weeks but in some cases will take months to fully normalize. If signs do not resolve in the 2-3-week period, other differentials should be considered.

If sensory deficits are observed, the recovery period may take longer.


Will most likely need a slurry or canned food gruel in the immediate period since the patient is unable to close the mouth but the tongue is still functional

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