Signs of Pain or Difficulty Opening Your Dog’s Mouth

Signs of Pain or Difficulty Opening Your Dog’s Mouth

While dogs typically perform wide, toothy yawns effortlessly, there are instances where they may exhibit signs of pain or difficulty when opening their mouths. These signs can include crying out, jerking their head back while attempting to yawn or chew on something firm, limited jaw opening, or struggling to eat and dropping food or toys. Identifying the source of the problem requires an examination of the head’s anatomy.


Bone and joint problems that can cause jaw pain or dysfunction include:

  1. Fracture of the jaw joint bones: Dogs and cats commonly experience this trauma from car accidents or being bitten by larger dogs. Fractures may result in a jaw that hangs open or shifts to one side. Treatment involves stabilizing the fractures to promote proper healing. Imperfect healing may lead to permanent issues like jaw arthritis or malformation.
  2. Dislocation of the jaw: Trauma can cause the jaw to dislocate, resulting in a closed-mouth lock or misalignment of the lower jaw. Recent dislocations can be reduced manually, while chronic cases may require surgery to restore normal jaw position and function.
  3. Jaw joint dysplasia: Similar to hip or elbow dysplasia, dogs and cats can develop dysplasia in their jaw joints. This condition can lead to open-mouth locking, especially during yawning when the jaw opens wider than usual. Surgery is a common treatment for frequent locking episodes.
  4. Craniomandibular osteopathy: This non-cancerous bone growth abnormality affects young, growing dogs between 3 and 8 months old, primarily impacting the head bones. It is hereditary in certain breeds but can occur in others as well. Treatment options are limited to supportive care and time, as the condition resolves once the bones mature. However, some dogs experience extreme pain, which may require euthanasia in severe cases.
  5. Tumors affecting jaw bones, cartilage, or surrounding soft tissues: These tumors can cause severe pain and dysfunction. Treatment options depend on the tumor type, pain level, and extent of dysfunction.

Muscular jaw problems can also contribute to pain or difficulty opening the mouth:

  1. Masticatory muscle myositis (MMM): An inflammatory condition where the immune system attacks the chewing muscles. MMM typically affects dogs around three years old and is most common in Labradors, Golden Retrievers, German Shepherds, Dobermans, and Cavalier King Charles Spaniels. It can cause gradual or sudden onset pain and swelling, leading to muscle atrophy and even complete mouth immobility. Early treatment involving immune system suppression can induce remission, but long-term medication may be necessary.
  2. Polymyositis: This condition can affect any skeletal muscle, including the chewing muscles. It can be immune-mediated or caused by various infections. Symptoms may include limping, weakness, difficulty walking, neck muscle movement problems, and pain or difficulty opening the mouth. Diagnosis involves multiple tests to determine the cause, such as blood tests, MRI, and muscle biopsy. Treatment and prognosis depend on the underlying cause and response to treatment.
  3. Trigeminal neuropathy: An inflammatory or cancerous condition affecting the trigeminal nerve responsible for closing the mouth muscles. Severe muscle wasting on one side of the head often accompanies this condition. Inflammatory cases can be managed medically, leading to resolution or remission. Tumors on the nerve may result in permanent changes with significant effects on the mouth and eye.
  4. Muscular dystrophy: A group of rare genetic conditions causing severe muscle, digestive, and cardiac problems. It typically leads to death, primarily affecting young dogs. While many breeds can be affected, males are more prone, while females are often asymptomatic genetic carriers. There is no known treatment. Prevention lies in not breeding affected animals and not repeating the breeding of known carriers. Genetic screening tests may be available for breeding dogs.
  5. Tumors affecting the chewing muscles commonly occur in older dogs and cats, leading to significant pain and dysfunction. The prognosis for such cases is uncertain and requires careful monitoring.
  6. Muscle trauma resulting from bite wounds or vehicular accidents is relatively common. With time and proper supportive care, these injuries typically heal.


There are other issues that can cause jaw pain or dysfunction, including:

  1. Foreign objects lodged in the back of the mouth, such as sticks or bones, can create physical obstacles and cause considerable pain when opening the mouth. They may also lead to infection in the jaw joint, resulting in septic arthritis. Diagnosis involves advanced imaging techniques like CT or MRI scans, followed by joint cleaning and bacterial culture sampling during surgery. Treatment includes antibiotics, pain medications, and joint supplements. It’s important to note that permanent changes to the joint are common in such cases.
  2. An abscess around the eye can be caused by tooth infections, penetration or migration of foreign objects like sticks, bones, porcupine quills, or bite wounds around the joint. Treatment depends on the underlying cause and typically involves administering antibiotics and flushing the wound.
  3. Tetanus infection, although more resistant in dogs compared to humans and other animals, can still occur. It can manifest as localized or generalized tetanus. In addition to “lockjaw,” dogs may exhibit a “sardonic grin” with their lips, eyes, and ears pulled back, stiff legs, difficulty or inability to walk, and potential breathing difficulties. Treatment for tetanus involves intensive supportive care, including antibiotics and antitoxin. The prognosis varies depending on the severity, but most dogs do recover.

If you notice any signs of jaw pain or dysfunction in your dog, it is crucial to seek veterinary assistance immediately. Early diagnosis and timely treatment play a vital role in ensuring your dog’s well-being.

Lauren W. Richman, DVM
Resident in Dentistry and Oral Surgery