History
A 28-year-old Quarter Horse gelding was referred to the University of Illinois Veterinary Teaching Hospital for evaluation of a suspected fracture of the left premaxilla that had occurred earlier in the day. The referring veterinarian reported an audible cracking noise when opening the horse's mouth with a McPherson full-mouth speculum during a routine oral examination. The horse had a history of chronic right-sided nasal discharge and intermittent swelling over the left rostral maxillary region.
On physical examination, there was minimal swelling over the left maxilla. Oral examination revealed a subgingival hematoma at the level of the interdental space rostral to the right maxillary second premolar tooth and feed material impacted between the left maxillary second and third premolar teeth. A fetid odor was noted upon opening the horse's mouth. There was no malalignment of the incisor teeth. All other physical examination findings were unremarkable. Radiographs of the skull were obtained (Figure 1).
Right dorsal–left ventral oblique (A) and left dorsal–right ventral oblique (B) radiographic views of the rostral aspect of the skull of a 28-year-old horse evaluated for a suspected maxillary fracture. Oblique radiographic views were obtained at 30° dorsal to the horizontal plane.
Citation: Journal of the American Veterinary Medical Association 239, 9; 10.2460/javma.239.9.1189
Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →
Radiographic Findings and Interpretation
Minimally displaced fractures of the right maxilla at the level of the interdental space and of the left maxilla, apparently through the alveolus at the left maxillary second premolar tooth, are evident (Figure 2). There is focal lucency around the roots of the left maxillary second premolar tooth surrounded by sclerosis, which is characteristic of a dentoalveolar infection, and there is evidence of generalized alveolar bone loss suggestive of periodontal disease. Similar alveolar bone loss is seen associated with the roots of the left maxillary first molar tooth and the right maxillary second, third, and fourth premolar teeth. Additionally, there is opacification of the right rostral maxillary sinus and a fluid line within the affected sinus that corresponds to fluid accumulation. The occlusal surface is irregular, indicating poor dental care, and there are several teeth missing from the mandible. Also, there are multiple sites with wide interdental spaces (diastema) on both the mandibular and maxillary arcades.
Same radiographic views as Figure 1. A—On the right dorsal–left ventral oblique view, there is a fracture line along the rostral portion of the left maxillary bone extending vertically from the alveolus at the left maxillary second premolar tooth (arrows). There is also a fracture through the interdental space in the right maxillary bone (arrowhead). B—On the left dorsal–right ventral oblique view, the fracture line in the right interdental space can be easily identified (white arrow). Notice the focal lucent area around the rostral most root of the right maxillary fourth premolar tooth suggestive of a tooth root abscess or a deep periodontal pocket and the fluid-gas interface within the right rostral maxillary sinus characteristic of the presence of fluid in the sinus (black arrow). There is also a line at the level of the second premolar tooth, which may represent soft tissue superimposition or a fluid-gas interface consistent with fluid accumulation in the nasal cavity (arrowheads).
Citation: Journal of the American Veterinary Medical Association 239, 9; 10.2460/javma.239.9.1189
Comments
Given the clinical and radiographic findings, bilateral maxillary bone fractures were diagnosed. In our hospital, the radiographic imaging protocol of the skull includes lateral, dorsoventral, right dorsal-left ventral oblique, and left dorsal-right ventral oblique radiographic projections. The oblique radiographic projections of the skull of the horse of the present report were obtained at 30° dorsal to the horizontal plane; they were essential to evaluate the affected tooth's apex and to identify the fracture through the right interdental space, which was not visible on the remaining radiographic projections.
Although the fracture was minimally displaced, it was stable and there was no malocclusion of the incisor teeth. Therefore, management was conservative because the horse was able to eat and drink without difficulties. Treatment consisted of oral administration of phenylbutazone (2.2 mg/kg [1 mg/lb], q 12 h, for 5 days), trimethoprimsulfamethoxazole (30 mg/kg [13.6 mg/lb], q 12 h, for 14 days), and diet modification (pelleted diet) to facilitate mastication. Dental extraction was delayed to avoid displacement or destabilization of the fractured left maxillary bone, which may occur during extraction of the affected tooth or opening the mouth with a mouth speculum.
After 16 weeks, a recheck radiographic examination was performed, which revealed that the right maxillary bone was healed; however, the fracture through the left maxillary bone was still visible. There was no radiographic evidence of fluid within the right rostral maxillary sinus. The horse was lightly sedated, and the left maxillary second premolar tooth was extracted intraorally without complications. Hospital discharge instructions included continuing to feed a pelleted diet and dental care in 10 to 12 weeks.
In the horse of the present report, the tooth root infection resulted in extensive alveolar osteomyelitis, likely predisposing the left maxilla to fracture.1 The etiology of both fractures may have been traumatic, especially the right maxillary fracture for which no radiographic evidence of surrounding osteomyelitis was present at the time of examination. Perhaps the same traumatic event could also explain the left maxillary fracture, for which the already weakened bone was a predisposing factor. In the horse of the present report, rostral maxillary sinusitis was likely due to the diseased maxillary tooth or deep periodontal pocket detected on radiographs.2
