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The vertical ramus is part of the lower jaw bone or 'mandible'. The mandible is made up of two identical bones fused in the middle at the mandibular symphysis. Each half of the mandible is composed of an 'L' shaped bone. The teeth are embedded in the horizontal part, whilst the upper arm or 'vertical ramus' extends above the temporomandibular joint (the jaw's 'hinge' ) and provides attachment for the powerful chewing muscles.
Partial excision of the vertical ramus is a challenging procedure. It is usually undertaken as a life-saving strategy for removing cancer, where euthanasia is the only other choice. It is most likely to be undertaken by a specialist orthopedic surgeon.
The patient's cancer is carefully staged using CT scans and histology of the draining lymph nodes. Radical surgery of this type should only be considered when the dog has a reasonable life expectancy post surgery, i.e. there is no spread to the lungs, liver, or draining lymph nodes.
Pre-emptive pain relief is administered and a general anesthetic given. The patient is positioned with the affected side uppermost and the fur clipped from over the face and neck. Under aseptic conditions, a long incision is made from the commissure of the mouth extending caudally.
The masseter (large cheek muscles) are dissected free from the vertical ramus and either reflected or removed (the latter if cancerous spread is a possibility.) Gum tissue is reflected from the bone. The exposed bone surface is cut either side of the tumor using an oscillating saw. The severed portion of bone is then removed, and the soft tissue sutured together to fill the deficit.
The lips and skin of the face are reconstructed.
Complete success involves the complete removal of the oral tumor. This depends on getting wide surgical margins that extend back to healthy tissue. In turn, this depends on the nature of the tumor, how aggressive it is, the degree of spread, and how accessible the diseased tissue is.
In practice, most partial excisions of the vertical ramus 'buy' the patient more time that they wouldn't have had because euthanasia would be necessary early on.
This is painful, invasive surgery and strong pain relief is required for at least 24 to 48 hours post surgery. This is includes drugs from the morphine family, so hospitalization is necessary.
The dog also needs to relearn how to eat. They may be offered liquidised soft food or moist food rolled into balls. Drooling blood stained saliva postoperatively is to be expected. Infection is a constant worry since the mouth is not a sterile place. Warm salt water washes, especially after eating, can help reduce this risk.
Wound breakdown is common, however, these mostly heal without further surgical intervention when infection is controlled.
Most dogs learn to eat for themselves after one to two weeks. The sutures are removed from the skin after 10 to 14 days.
The cost of surgery is liable to run into thousands of dollars, which includes the surgical procedure and the nursing care in the postoperative period. In addition, there are substantial work up costs. These include a CT scan of the head and neck (around $900 upwards), ultrasound of the abdomen ($500 upwards), chest radiographs ($150 upwards) and histology of aspirated lymph nodes (around $100 for three samples).
Partial excision of the vertical ramus is largely considered a salvage procedure. It may buy extra time for a patient where the only other option is euthanasia. Staging the cancer is a crucial part of the preoperative assessment, since those with far advanced cancer with extensive secondary spread should not be put through such major surgery.
Cancer of the oral cavity is a recognized problem in dogs. These cancers tend to arise spontaneously and so there is little an owner can do in order to prevent it. Early recognition that the dog has a problem and early diagnosis mean spread is less likely and also the surgery may be less extensive.
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