Fracture of the Mandible (Lower Jaw) in Dogs
Fractures of the mandible (lower jaw) are usually the result of major trauma, especially to the head, but can be caused by disease of the bone itself, dental disease, or sometimes by the veterinarian during extraction of diseased teeth. These fractures can occur at any location along the length of the bone from the midpoint where the two halves of the mandible meet in the front, back to the temporo-mandibular joint (TMJ). The fractures can occur on both sides of the jaw at the same time. Many of these fractures are “open” but occasionally “closed” fractures do occur. Mandibular fractures can also be categorized as “simple” or “comminuted.”
Depending on the nature of the fracture and the age of the animal, different methods of repair may be indicated for each situation. Mandibular fractures can have serious complications if not repaired or if the repair fails.
What to Watch For
Signs of a fractured mandible in dogs may include:
Diagnosis of Fracture of the Mandible in Dogs
A thorough physical examination including examination of the oral cavity can often determine if a mandibular fracture is present. Additional tests may include:
No laboratory tests are required to make the diagnosis.
Treatment of Fracture of the Mandible in Dogs
Treatment for a fractured mandible varies depending on the area of the fracture and the severity. Since most mandibular fractures are trauma related, emergency care for concurrent problems caused by the trauma is often performed before mandibular fracture repair.
Some fractures of the mandible can be managed without surgery by placing a muzzle on the dog’s snout, while some require anesthesia and surgical stabilization of the bone fragments for the best results.
If dental disease is suspected as the cause for the fracture, a full dental cleaning with extractions of some teeth may be required.
Injectable analgesics (pain medications) are given to the animal while being treated in the hospital and may be continued orally once discharged. Antibiotics are commonly given to minimize the chance for systemic infection from bacteria in the mouth.
Home Care and Prevention
With conservative management in a muzzle, or after surgical repair of the fracture, the dog should be kept restricted from activity for several weeks and fed only a soft gruel that does not require chewing.
A recheck appointment with the veterinarian will occur in several weeks to evaluate how the bone is healing (possibly with new radiographs), to monitor the dog’s progress, and to make sure it is safe to return to a regular diet.
Many traumatic events are true accidents and thus unavoidable. Dental hygiene and routine cleaning by the veterinarian may prevent severe dental disease that could lead to mandibular fractures.
In-depth Information on Fracture of the Mandible in Dogs
Motor vehicle trauma is a frequent cause of mandibular fractures in dogs, as well as falling from a height (such as out a window) and landing on the face. Dogs of both sexes and of any age are susceptible to this type of trauma if not kept properly restrained.
Dogs can also develop non-traumatic fractures of the mandible when certain disease conditions exist. These fractures, also known as “pathologic fractures,” can occur if the dog has severe dental disease leading to destruction of the bone supporting the teeth, is malnourished, has a systemic illness such as kidney disease, has an endocrine disorder such as hyperparathyroidism, has a bone infection (osteomyelitis) or has cancer of the bone.
Symptoms caused by fracture of the mandible may be relatively subtle, with reluctance to play or chew on toys or food, or more obvious, with inability to close the mouth, bloody saliva dripping from the mouth, or inability to eat at all.
The mandible is one of the hardest bones in the body and a great deal of force is necessary to break the bone. Frequently the two halves of the mandible split at the midline (mandibular symphysis fracture). Also instead of a true fracture, the temporo-mandibular joints may dislocate (luxate) making the jaw non-functional.
When the bone does break, the fracture can occur on one or both sides, can be “simple,” if the bone breaks into two pieces, or “comminuted,” if there are multiple pieces, and can occur anywhere along the length of the bone. Because there is relatively little soft tissue covering the mandibles in the mouth, these fractures are usually “open” (bone exposed). Open fractures have a greater chance of getting infected and may have more complications than closed fractures.
Each case of mandibular fracture needs to be evaluated in its entirety (age of animal, severity of the fracture, experience of the surgeon, and financial concerns of the owner) to determine the most appropriate and best form of treatment.
Inappropriate case management, inadequate surgical stabilization or poor aftercare can lead to complications such as non-unions (fractures that will not heal), malunions (fractures that heal in an abnormal direction or orientation resulting in malocclusion of the teeth and difficulty chewing), or osteomyelitis (bone infection).
In-depth Information on Diagnosis
Thorough physical examination is very important to make sure your pet is not showing signs of hypovolemic shock secondary to the trauma or blood loss. It is also important to make certain that there are no other injuries present. Additional tests include:
No laboratory tests are required to make the diagnosis.
In-depth Information on Treatment
Emergency care for concurrent problems is the first part of treatment. Shock is a frequent result of major trauma and must be treated quickly. Treatment for shock involves intravenous fluid administration to maintain blood pressure and adequate oxygen delivery to the body. Injury to the lungs and chest cavity are also commonly seen after major trauma and may require supplemental oxygenation or removal of free air (pneumothorax) from around the lungs. After emergency treatment has begun, additional treatments include:
Methods for surgical stabilization of other mandibular fractures include wires placed around the teeth, wires placed in the bone, bone plates and screws, and external fixators (pins holding the bone fragments stable through holes in the skin, like a scaffolding). Each of these methods may be used separately or in combinations to provide stability to the bone fragments while they heal. In some cases, the upper and lower jaws may be wired together or the upper and lower canine teeth may be temporarily cemented together to hold the fragments in position while the bones heal. These dogs may require the use of a feeding tube placed directly into the esophagus or stomach to allow nutrition and hydration without the need for chewing and swallowing.
Follow-up Care for Dogs with Fracture of the Mandible
After discharge from the hospital, the dog must be restricted from activity to allow the fracture time to heal properly. Activity must be restricted for several weeks after surgery; the duration will vary depending on the severity of the injury and any concurrent injuries the animal may have. Restricted activity means that the animal should be kept confined to a carrier, crate, or small room whenever he cannot be supervised. Playing and rough-housing should be avoided, even if he appears to be feeling well. It is especially important that dogs with mandibular fractures not be allowed to chew on toys or other objects and be fed only soft food or blenderized gruel.
Animals whose fracture was repaired with an external fixation device will have pins exiting the skin. The “pin tracts” should be monitored daily for excessive swelling or discharge. Some discharge is normal and any crusty build-up that occurs at these sites can be gently cleaned with warm water.
Fractures that are repaired with internal fixation (wires or bone plates and screws) will have a skin incision under the jaw that needs to be monitored daily for signs of excessive swelling or discharge. These can indicate problems with the incision or infection.