Mandibular Fractures - Cat & Dog

Small Animals

Introduction

Mandibular fractures are commonly seen in dogs and cats. With cats they often 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, metabolic disease and neoplasia.

Signalment

Symphyseal fractures are most common in cats, particularly entire males as they have a tendency to try and escape buildings to find mating females. Fracture of the mandibular body is far more common in the dog, and there are no breed, age or sex predispositions.

Clinical Signs

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.

Treatment

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

Symphyseal fractures are repaired using circumferential wire. An skin incision should be made in the ventral mandible at the level of the 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 pliars. The wire is then cut short and places flush with the skin. The skin incision closed with a single suture. Healing occurs in 5-7 weeks, at which point the wire can be removed.

Mandibular Body Fractures

Fractures of the mandibular body are normally more complex and healing takes approximately 9-10 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. t is a fairly simple, cheap and effective method.

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. It cannot be used in cats, brachycephalic dogs and not compliant patients.

Interdental wire and acrylic bonding (IWAB): This method cannot be used in cats but is a effective and cheap technique for use in the dog. 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 surround 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 placed at the junction of the body and ramus of the mandible, at the ventral border of the mandibular body and the mid-buccal surface of the mandible.

Hemimandibulectomy: This is considered a salvage procedure.

Ramus fractures

Ramus fractures 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.

If the fracture is open, then suitable antibiotics should be given to prevent osteomyelitis and soft tissue infection. Antibiotics should also be given to any animals with dental disease.

Prognosis

The prognosis for symphyseal' and ramus fractures is good. Complications are much more common with fractures of the mandibular body - particularly if ' 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.

Large Animals

Introduction

Mandibular fractures often occur when animals catch their lower jaw for example on wire fencing, the rings on the stable walls or under a manger. Normally the rostral mandible is avulsed as they try to free themselves by pulling backward. Fractures can also occur in the ramus of the mandible, however these are much less common.

Signalment

It is most common in young animals, particularly horses.

Clinical Signs

The horse usually presents with a history of inappetance. Clinical signs include dysphagia, halitosis, salivation, oral haemorrhage, crepitus, abnormal incisor occlusion and discharging-tracts.

The fracture can be visualised on oral exam; it is normally open and located in the rostral mandible, caudal to the incisor teeth (with or without involving the incisors). This avulsion fracture can be unilateral or bilateral. Soft tissue structures adjacent to the fracture may also be damaged. Care should be taken when using a gag as this may displace the fracture.

Diagnosis

Diagnosis should be achievable from clinical signs alone, however radiography is a useful ancillary test - multiple views should be taken to show the extent and position of the fracture and also reveal any additional fracture that may be present.

Treatment

Initially, contamination of the site should be grossly removed and then lavaged with copious amounts of isotonic fluids. Then the fracture should be reduced and stabilised using wires looped around the incisors, which are then anchored either to the canines or to bilateral cortical screws located in the diastemal region. This should be performed under general anaesthesia. Due to the high level of contamination, antibiotic treatment is recommended. Implants should be removed if the fracture is stable after 6-12 weeks to avoid chronic infection.

Prognosis

The prognosis is good. The excellent blood supply to the head, in particular the mandibular region, means that these fractures almost always heal quickly and without complications. there is usually acceptable cosmetic appearance despite being grossly contaminated. This can be compared to open contaminated fractures elsewhere in the body, which, unless they have small fragments that can be easily removed, carry a very guarded prognosis due to the high incidence of osteomyelitis at the fracture site.

Mandibular Fractures - Cat & Dog Learning Resources
Flashcards Test your knowledge using flashcard type questions	Equine Orthopaedics and Rheumatology Q&A 03 Small Animal Orthopaedics Q&A 03

References

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

May, SA & McIlwraith, CW (1998) Equine Orthopaedics and Rheumatology Self-Assessment Colour Review Manson Publishing Ltd

RVC staff (2009) Urogenital system RVC Intergrated BVetMed Course, Royal Veterinary College

Tremaine, H (1997) Dental care in horse In Practice 1997 19: 186-19

Tremaine, H (2004) Management of skull fractures in the horse In Practice 2004 26: 214-22