Why Is My Dog’S Mouth Locked Shut?

Lockjaw refers to a dog’s inability to fully open or close their mouth due to spasms or rigid contractions of the jaw muscles. It is a relatively rare condition in dogs that can occur for a variety of reasons, including injury, infection, neurological issues, or as a side effect of certain medications. Lockjaw prevents normal use of the jaw, causing difficulty eating, drinking, and barking. It is important for dog owners to recognize symptoms of lockjaw and seek prompt veterinary care, as it can lead to malnutrition, dehydration, and other health complications if left untreated.

While scary for dog owners, lockjaw is usually manageable with proper treatment and monitoring from a veterinarian. Knowing the potential causes and being vigilant about symptoms can help dog owners address this condition early. With a thorough understanding of the condition, dog owners can better support their pets through recovery and take steps to prevent reoccurrence. This article will provide an overview of lockjaw in dogs, from causes and symptoms to diagnosis, treatment, and prevention.

What is Lockjaw?

Lockjaw, also known as trismus, is a condition in dogs where the mouth becomes locked shut due to spasms of the jaw muscles. It is characterized by the inability to open the jaw fully or at all.

The medical term for lockjaw is trismus. It refers to sustained contraction of the muscles that control jaw movement, resulting in restricted ability to open the mouth. Essentially, the dog’s jaws become “locked” either partially or completely.

Lockjaw prevents the dog from being able to open its mouth normally. A dog with lockjaw may only be able to open their mouth a small amount, or in severe cases not at all.

This inability to open the mouth can make it very difficult and painful for the dog when trying to eat, drink, pant, and perform other essential functions requiring use of the mouth.

While lockjaw can sometimes resolve on its own, it often requires veterinary treatment. Identifying and addressing the underlying cause is important.


There are several potential causes of lockjaw in dogs.[1] One of the most common is an injury, such as a fractured jaw or dislocated temporomandibular joint (TMJ). Fractures can occur from trauma like being hit by a car or falling from a height. Dislocations and luxations of the TMJ may happen from the dog opening its mouth too wide. These types of injuries are very painful and cause the dog to refuse to open its mouth.

Abscesses in the mouth, face, or throat can also lead to lockjaw in dogs. Abscesses form when bacteria get trapped under the skin and multiply, creating a pocket of pus. The swelling and pain from abscesses can make it difficult for the dog to open its mouth.[2]

Tetanus is another potential cause of lockjaw in dogs. Tetanus is caused by a bacterial toxin that affects the nervous system, leading to painful muscle contractions and spasms. The muscles of the jaw are often the first to be impacted, causing the mouth to lock up.[1]

Other less common causes include neurological disorders, rabies, dislocated jaw, masticatory myositis, and hypocalcemia. However, injuries, abscesses, and tetanus are the most frequently seen causes of a dog’s mouth becoming locked shut.

Symptoms of Lockjaw in Dogs

The most obvious symptom of lockjaw in dogs is an inability to open the mouth. The dog’s jaws become tightly fixed together and they are unable to separate their upper and lower jaw. This prevents them from being able to eat, drink, bark, or open their mouth at all.

Excessive drooling is another common symptom. Since the dog cannot swallow properly with their mouth locked shut, saliva tends to pool in their mouth and drip out. You may notice thick ropey strands of drool hanging from their mouth.

Swelling of the head, face, and neck muscles often accompanies lockjaw. The muscles cramp and contract forcefully, which leads to inflammation and swelling around the jaw and neck. This can be quite painful and tender to the touch.

Other symptoms include distress, anxiety, restlessness, stiff gait, muscle tremors or spasms, and rapid breathing. Dehydration can also occur since the dog is unable to drink.


Veterinarians will diagnose the cause of lockjaw through a physical examination of the dog’s head and mouth. They will look for signs of injury, inflammation, or abnormalities that could be contributing to the inability to open the mouth. Gentle palpation of the temporomandibular joints and mandible may reveal pain, popping, or crepitus which can aid diagnosis. Imaging such as X-rays or CT scans of the skull may be recommended to evaluate the temporomandibular joint for subluxation, fractures, or bony changes. Bloodwork can also be helpful to check for signs of infection or other systemic issues.

According to one source, “Although care will be taken, your veterinarian will attempt to open your dog’s mouth to look for fractures, wounds, loose teeth, and evidence of dislocation or other abnormalities. Your veterinarian will palpate the head and neck, looking for fractures or areas that are painful and may limit motion.” (https://wagwalking.com/condition/lockjaw)


The treatment for lockjaw will depend on the underlying cause. Tetanus and other bacterial infections are commonly treated with antibiotics like penicillin or metronidazole to kill the bacteria and stop toxin production. Anti-inflammatory drugs may also be used to reduce muscle spasms and pain. In severe cases of tetanus, antiserum is given to neutralize toxins in the bloodstream.[1]

For cases of masticatory muscle myositis, immunosuppressive drugs like prednisone are the main treatment. These help stop the immune system from attacking the muscles. Pain medication may also be prescribed for discomfort. In some cases, surgery is done to release the tightening muscles.[2]

If an object is lodged in the mouth or throat, the vet will carefully remove it. Occasionally teeth need to be extracted if they are damaged or infected. Physical therapy exercises can help strengthen the jaw muscles and restore normal motion after injury or illness.

No matter the cause, ensuring the dog stays hydrated and receives proper nutrition during recovery is very important. The vet may recommend soft foods, add water to kibble, or use a feeding tube temporarily.


The recovery process and timeline for dogs with lockjaw depends on the underlying cause. For mild cases caused by trauma or muscle spasms, recovery may only take a few days to a week with rest, anti-inflammatory medication, and gentle physical therapy to regain mobility 1. More severe cases like tetanus often require 1-2 weeks of hospitalization and supportive care before improvement is seen 2.

If an underlying illness like an ear infection triggered the lockjaw, treating that condition can help speed recovery. Medications may be prescribed to treat pain, inflammation, and muscle spasms associated with lockjaw. Physical therapy involving gentle massage and range of motion exercises helps regain normal jaw function once muscle spasms subside. Most dogs make a full recovery within 2-4 weeks, though some may take longer depending on the severity.

Close monitoring and follow-up vet exams are important during recovery to ensure the dog is improving and not worsening. Owners should follow all at-home care instructions provided by the vet. Full recovery is achieved once the dog can open its mouth normally and painlessly again.


There are a few things you can do to help prevent injuries that could cause your dog’s mouth to lock shut:

  • Avoid rough play that could result in head/mouth injuries. While playful mouthing is normal for dogs, take care to avoid overly roughhousing in ways that could harm your dog’s jaw.
  • Use a soft muzzle or head collar when appropriate. For dogs prone to chewing or biting, these accessories can protect from self-injury.
  • Keep your home and yard clear of harmful debris and objects. Pick up any sharp sticks, rocks, glass, or other objects that could potentially injure your dog.
  • Feed an age-appropriate diet. Senior dogs with worn teeth or young pups with incoming teeth may find hard kibble uncomfortable. Adjust food as needed.
  • Practice good dental care. Regular teeth brushing, dental chews, and professional cleanings can help avoid dental infections that may contribute to lockjaw.
  • Vaccinate your dog against rabies and other infectious diseases as recommended by your vet. Proper immunization helps prevent potential viral contributors to lockjaw.

While lockjaw can arise suddenly in some cases, taking preventative measures can reduce the risks. Work closely with your veterinarian to keep your dog safe, healthy, and happy.


The prognosis for dogs with lockjaw depends on the underlying cause. In cases of tetanus, the prognosis is poor if intensive care is not given immediately. According to one study, the mortality rate for dogs with tetanus was over 50% even with appropriate treatment.[1] For dogs who survive tetanus, the recovery period can be prolonged, taking weeks to months. Some dogs may experience permanent nerve damage or muscle weakness.

The prognosis is better for cases of lockjaw caused by temporomandibular joint disorders or fractures. With appropriate treatment like anti-inflammatory medication, jaw rest, and sometimes surgery, many dogs make a full recovery. However, if the condition is left untreated, permanent damage can occur leading to long-term difficulty eating and opening the mouth.

For cases of masticatory muscle myositis, dogs generally respond very well to steroid treatment and make a full recovery within a few weeks. However, relapse is common if immunosuppressive therapy is discontinued too soon. Long term immunosuppression may be necessary in some cases.

Overall, the earlier lockjaw is diagnosed and treated, the better the prognosis. Any dog exhibiting difficulty opening their mouth should be evaluated by a veterinarian immediately to identify the underlying cause and begin appropriate treatment. Delaying treatment risks permanent complications.

[1] https://pubmed.ncbi.nlm.nih.gov/18512621/

When to See a Vet

It’s essential to take your dog to the vet right away if signs of lockjaw emerge. Lockjaw is a medical emergency that requires immediate veterinary attention. Some warning signs that warrant an urgent vet visit include:

– Inability to open or close the mouth at all
– Excessive drooling or foaming at the mouth
– Difficulty eating or drinking

– Lethargy or lack of energy
– Fever
– Swelling of the head or neck area
– Evidence of injury to the mouth, jaws, or head
– Seizures or muscle tremors

The longer lockjaw persists untreated, the higher the risk for serious health complications. Dehydration, malnutrition, aspiration pneumonia, and even death can occur if veterinary care is delayed. At the first sign of lockjaw, do not wait – seek emergency vet services right away. Timely treatment is crucial for preventing permanent damage or loss of life.

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