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Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Dog Veterinary
Satisfied Customers: 23758
Experience:  University of California at Davis graduate veterinarian with 44 years of experience
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My dogs mouth will not shut. What can I do?

Customer Question

My dogs mouth will not shut. What can I do?
Submitted: 4 months ago.
Category: Dog Veterinary
Expert:  Dr. Michael Salkin replied 4 months ago.

You're speaking to Dr. Michael Salkin. Welcome to JustAnswer. I'm currently typing up my reply.

Customer: replied 4 months ago.
How long will this take? My dogs mouth has been locked open for over a half hour
Expert:  Dr. Michael Salkin replied 4 months ago.

The most common cause of failure to be able to close the mouth is a trigeminal neuropathy. The trigeminal nerve is cranial nerve V and is responsible for sensation in the face and motor functions such as biting and chewing. Here's a synopsis of this disorder for you:

Definition: 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)

Synonym: Dropped jaw

Epidemiology (Species, Age, Sex): 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 association (related to a cancer elsewhere in the body)

Clinical Presentation

Disease Forms/Subtypes

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.

Diagnostic Overview: 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

Treatment: Spontaneous recovery usually occurs in 2-3 weeks. Please respond with further questions or concerns if you wish.

Customer: replied 4 months ago.
I need to know what to do. Should I take him to a vet?
Expert:  Dr. Michael Salkin replied 4 months ago.

If you can manually close his mouth, it's not "locked" open. He most likely has a "dropped jaw" due to trigeminal neuropathy. His vet has no therapy for this and as long as he can eat and drink well enough, "watchful waiting" is appropriate for up to 2-3 weeks. If you're uncomfortable doing so, I have no objection to your having Titus's vet take a look at him. Feel free to share our conversation with his vet.

Your dog might need a slurry or canned food gruel in the immediate period since he's is unable to close his mouth (but the tongue is still functional).

Customer: replied 4 months ago.
He can not eat or drink at this time.
Expert:  Dr. Michael Salkin replied 4 months ago.

Thank you. He's likely to need a feeding tube. It's best that his vet take a look at him.

Customer: replied 4 months ago.
Thank you
Expert:  Dr. Michael Salkin replied 4 months ago.

You're welcome. I can't set a follow-up in this venue so please return to our conversation - even after rating - with an update at your convenience.

Customer: replied 4 months ago.
My vet can see him in the morning.
Expert:  Dr. Michael Salkin replied 4 months ago.

Sounds good. See if you can place a canned food gruel on his tongue which he should then be able to move down his throat. Water needs to be given in that manner too lest he dehydrates.

Expert:  Dr. Michael Salkin replied 4 months ago.

I'm just following up on our conversation about Titus. How is everything going?

Dr. Michael Salkin

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