Fractures of the rostral part of the mandible may be bilateral.
Rostral fractures can occur when horses bite onto vertical metal bars in the stall; the horse bites the bar with its head in a slightly horizontal position and then suddenly pulls back after positioning its head vertically. Because of the relatively large total width of the lower incisors, they become wedged between the bars, resulting in alveolar fractures with rostral dislocation of the incisors. Such fractures are more common in nervous or curious young horses.
Typically, the fracture line follow the line of the teeth roots. They can involve just one or multiple teeth. Rostral fractures are the least stable fractures because the cheek teeth and muscles, which provide some stability, are lacking in this region.
A diagnosis is usually possible based on a clinical examination. A radiographic and/or endoscopic examination may be performed to rule out additional injuries. These fractures often cause little pain and, if the dislocation is minimal, can be missed and left to heal without treatment.
Rostral fractures can occur uni or bilaterally.
Dental alveoli are usually involved in these fractures but the teeth themselves are rarely fractured. If dental alveoli are involved, loss of one or more teeth can result either immediately during the traumatic event or later as a result of infection.
In some cases, the teeth roots are fractured (see examples). This requires additional examinations of the teeth at a later stage.
Fractures of the mandibular interdental space and horizontal ramus can be bilateral, and the fragments are either slightly displaced or severely displaced and highly mobile.
These fractures are very common and their location and type vary greatly. Typically, the fracture line runs from craniodorsal to caudoventral. The fracture starts dorsally either close to the incisors or close to the cheek teeth and runs caudally and ventrally. It is very rare, that the fracture runs from rostroventral to caudodorsal.
These fractures may be unilateral or bilateral and the fragments are either slightly displaced or severely displaced and highly mobile.
Fractures of the interdental space and horizontal ramus: Clinical signs
Clinical signs can be moderate or severe pain and typically the skull has an asymmetric appearance.
Fractures of the vertical part of the mandibular branch are rare. They can occur as fractures with minimal dislocation but also as unstable fractures with more severe dislocation, which may occur when a horse has its head wedged between two solid objects and withdraws forcefully. In most cases at least some comminution is present.
Fractures that involve the temporomandibular joint are usually associated with severe clinical signs.
CT imaging is strongly recommended and helps with fracture identification.