Mandibular Fractures - Cat & Dog
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Mandibular fractures are commonly seen in dogs and cats. With cats they often form part of the high-rise syndrome, when a cat falls from a height and suffers facial trauma as a result, or as a consequence of a road traffic accident. Canine mandibular fractures are normally caused by fighting or other trauma. Fractures can also occur in both species as a result of dental disease (most notably periodontal disease in small breed dogs), metabolic disease and neoplasia.
Symphyseal fractures are most common in cats. Fracture of the mandibular ramus is far more common in the dog, and there are no breed, age or sex predispositions.
Animals may present with a history of trauma - it is particularly important to check any trauma cases (particularly cats) for mandibular fractures. Otherwise they may have a history of dysphagia or inappetance. On physical exam instability of the jaw, malocclusion, halitosis and oral pain may be evident. Often mandibular body fractures are open, therefore there may be an open wound over the fracture site. Patients may be presented when the owner notices blood from the mouth.
The method of fracture fixation varies according to the type of fracture. However the aims of the fixation is always the same: to restore normal, functional occlusion, to avoid iatrogenic damage to teeth, achieving stable fixation that encourages healing and early return to function.
Symphyseal fractures are repaired using circumferential wire. A skin incision should be made in the ventral mandible. The wire (0.5-0.7mm gauge - dependant on the size of the animal) should then be guided around the lateral borders of the mandible using an 18G hypodermic needle. The fracture should be aligned and the wires tightened by twisting them together using wire-tightening pliers. The wire is then cut short and placed flush with the skin. The skin incision is closed with a single suture. Healing occurs in 5-7 weeks, at which point the wire can be removed.
Mandibular Ramus Fractures
Fractures of the mandibular ramus are normally more complex and healing takes approximately 8 weeks. Numerous methods available for fracture stabilisation:
Conservative treatment: Conservative treatment can be attempted but it is associated with high complication rates and slow recovery.
Interarcade canine acrylic bonding (ICAB): This method uses acrylic dental composite to bond the mandibular and maxillary canine teeth and stabilise the fracture. It is necessary to clean and acid etch the teeth before a thin layer of dental adhesive is applied to the canine teeth. Dental adhesive and the composite are applied to the canines, with the fracture held in reduction until the composite has dried. It is a fairly simple, cheap and effective method for caudal mandibular fractures.
Tape muzzle: A tape muzzle can be used in dogs to stabilise the fracture before it is repaired surgically or in cases with financial constraints. It is also suitable for ramus fracture stabilisation. A modified technique can be used in cats and brachycephalic dogs but is unlikely to be of use in non-compliant patients.
Interdental wire and acrylic bonding (IWAB): This method is an effective and cheap technique for use in the dog and can be used in cats although is more fiddly. The wire and bonding are placed on the dorsal tension side of the mandible, causing minimal iatrogenic damage and good stabilisation.
Interfragmentary wiring: This technique is not recommended as it rarely achieves appropriate stabilisation and tends to cause damage to the surrounding teeth and soft tissues.
External skeletal fixator: ESF pins connected by acrylic frames provide good fracture stabilisation. The acrylic is light, cheap and easy to apply, however it is important to avoid damage to adjacent structures when placing the pins.
Bone plates: Bone plates cane be used but have limited positions of application to avoid iatrogenic damage to neurovascular bundles and teeth unless miniplates are used.
Hemimandibulectomy: This is considered a salvage procedure.
Fractures of the coronoid process
These may be treated either conservatively or with interdental wire and acrylic bonding (ICAB), and healing is normally achieved within 6 weeks.
Placement of an oesophageal feeding tubes is recommended for all mandibular fracture cases other than simple symphyseal fractures to prevent nutritional complications.
The prognosis for symphyseal and ramus fractures is good. Complications are much more common with fractures of the mandibular body - particularly if teeth are involved in the fracture, and prognosis will depend on whether or not these complications occur. They include poor occlusion, implant failure, infection of the bone or soft tissue, joint disease, non-union and malunion.
|Mandibular Fractures - Cat & Dog Learning Resources|
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|Small Animal Orthopaedics Q&A 03|
Glyde, M & Lidbetter, D (2003) Management of fractures of the mandible in small animals In Practice 2003;25:570-585
Lewis, DD & Parker, RB & Bloomberg, MS (1998) Self-Assessment Colour Review Small Animal Orthopaedics Manson
RVC staff (2009) Urogenital system RVC Intergrated BVetMed Course, Royal Veterinary College
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