A dog or cat that cannot close or open its mouth
If your pet's lower jaw suddenly drops and the mouth won't close or, the other way round, your pet can't or won't open it, don't wait. Possible causes include a jaw fracture, luxation of the temporomandibular joint (TMJ), a foreign body wedged between the teeth, nerve dysfunction, inflammation of the chewing muscles or of the tissues behind the eye, or severe mouth pain. Most of these conditions need help the same day.
Important note for owners
Different causes look similar from the outside, yet their treatment is completely different, so never try to “put the jaw back” yourself: with a fracture or luxation it makes the injury worse.
Most common possible causes
- —Jaw fracture. Usually after an injury — a fall, a blow or a fight. In small dogs, a lower jaw weakened by advanced periodontal disease can break even with minimal force.
- —Joint luxation or jaw locking. The temporomandibular joint is displaced, or the jaw locks wide open (this happens in cats and some dogs): the mouth won't close or the teeth don't meet properly. Other joint problems can, conversely, make it hard to open the mouth.
- —Foreign body. A piece of stick or bone can get wedged between the teeth or across the palate and stop the mouth from closing.
- —Trigeminal nerve dysfunction (“dropped jaw”). Your pet suddenly cannot close its mouth, drools and has difficulty eating. This diagnosis is made after other causes have been ruled out.
- —Rabies. A suddenly dropped lower jaw, drooling and difficulty swallowing — especially in an unvaccinated pet or after contact with a wild or stray animal.
- —Masticatory muscle myositis in dogs. Immune-mediated inflammation of the chewing muscles: at first they are painful, later the dog finds it hard to open its mouth, and the temporal muscles shrink — the head looks “sunken”.
- —Retrobulbar abscess or inflammation. An abscess or inflammation behind the eyeball makes opening the mouth painful; sometimes the eye visibly bulges.
When not to postpone an exam
- ✓The mouth doesn't close fully, and this is getting worse gradually
- ✓Your pet can't or won't open its mouth wide, or whimpers when chewing
- ✓Painful chewing muscles: your pet avoids being touched on the head
- ✓The temple muscles have shrunk and the head looks “sunken”
- ✓The teeth no longer meet the way they used to
- ✓Your pet eats slowly or food falls out of its mouth
Urgent help needed
- ✓An injury to the face or jaw, and your pet cannot open or close its mouth normally
- ✓Difficulty breathing
- ✓Your pet cannot swallow and is drooling heavily
- ✓The mouth suddenly stopped closing
- ✓Rapidly increasing swelling of the face, cheek or under the eye
- ✓Complete refusal of food and water
What you can do at home
- ✓Stay calm and talk to your pet quietly: stress and sudden movements make the pain worse.
- ✓Transport your pet gently: a small pet in a carrier, a large one with its body supported and no pressure on the jaw.
- ✓Offer water, but don't force your pet to drink or eat.
- ✓After an injury, go straight to a clinic that provides emergency care: the general condition is stabilised first, and dental surgery is the next step.
What not to do at home
- —Don't try to force the mouth closed or open, or to “put the jaw back”
- —Don't put your fingers in the mouth or feel for a “bone in the throat”: your pet may bite, and a dropped jaw with drooling can be a sign of rabies
- —Don't give human painkillers — many of them are toxic to cats and dogs
- —Don't wait until the morning if the problem came on suddenly or after an injury
What diagnostics may be needed
- ✓Assessment of the general condition and examination of the mouth, jaws and joints — fully, often only under sedation or anaesthesia
- ✓X-rays of the jaws and teeth, including teeth in the fracture line
- ✓A CT scan may be needed — for the TMJ and jaw fractures it is often the most informative method
- ✓If masticatory muscle myositis is suspected — a blood test for type 2M fibre antibodies (ideally before steroid treatment starts), sometimes a muscle biopsy
- ✓A neurological assessment when nerve dysfunction is suspected — a consultation with a neurologist or your regular vet may be needed
A fracture, a luxation and a locked jaw look almost the same from the outside, and a pet in pain won't allow an examination. The joints and fracture lines are visible only on imaging, while myositis or nerve dysfunction is confirmed by separate tests.
Unfamiliar term in the diagnosis?If the report mentions TR, FCGS, pulpitis or a periodontal stage, the glossary explains each term briefly.GlossaryHow treatment may proceed
- ✓Treatment depends on the cause; after an injury, the general condition is stabilised first
- ✓Reduction of a TMJ luxation or a locked jaw under sedation or anaesthesia
- ✓Stabilisation of jaw fractures — for example, with intraoral splints or wiring; teeth in the fracture line are treated or extracted when clinically indicated, after X-rays
- ✓Removal of a foreign body and care of the injured tissues
- ✓For myositis — immunosuppressive therapy prescribed by a vet
- ✓For idiopathic trigeminal neuropathy — supportive care (help with eating and drinking); function usually returns within a few weeks
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Frequently asked questions
If the mouth suddenly stopped closing, there was an injury, or your pet can't swallow or is struggling to breathe — no, help is needed straight away. If opening the mouth is becoming harder gradually, an examination is needed within days, not weeks.
In small dogs, the tooth roots take up a large part of the lower jaw. Advanced periodontal disease destroys the bone around them, and the jaw becomes thin and fragile — then a jump, play or even chewing can be enough. That is why treating periodontal disease also helps prevent such fractures.
After an injury, go first to a clinic that provides emergency care: they will assess breathing, bleeding and the general condition. If there was no injury and your pet has gradually stopped opening its mouth, message me — I'll suggest which tests to start with.
Wash the wound straight away with soap and water for at least 15 minutes and see a doctor immediately (an emergency or injury clinic). A dropped jaw with drooling can be a sign of rabies, so tell the doctor about your pet's symptoms and inform your vet as well.
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