History and Physical Examination Findings
A 2.5-year-old 38.5-kg (84.7-lb) castrated male German Shepherd Dog presented to a veterinary medical teaching hospital (VMTH) urgent care due to concerns for right mandibular swelling. Three weeks prior to presentation, the primary care veterinarian evaluated the dog for an enlarged right mandibular lymph node and the inability to open the jaw without crying out in pain. Deracoxib (1 mg/kg [0.5 mg/lb], PO, q 24 h) was prescribed, and sedated skull radiographs were performed, which revealed no abnormalities. The dog was diagnosed with a presumptive oral abscess, and amoxicillin–clavulanic acid (19.4 mg/kg [8.8 mg/lb], PO, q 24 h) was prescribed. Approximately 1 week before presentation at the VMTH, the dog presented at a second veterinarian for persistent swelling around the right mandible, bloody oral discharge, and signs of oral pain. During a sedated oral examination, a right mandibular abscess was identified on the mucosa ventral to the right mandibular fourth premolar. It was lanced intraorally and flushed with sterile saline. Enrofloxacin (5.4 mg/kg [2.4 mg/lb, PO, q 24 h]) was prescribed, and the dog was referred to the VMTH.
On presentation to the VMTH, the general physical examination was unremarkable. Oral examination revealed purple intrinsic staining of the right mandibular canine, right mandibular fourth premolar and first molar teeth, and multiple parulides associated with the right mandibular fourth premolar and first molar teeth. Palpation of the mandible showed moderate right mandibular thickening along the ventral border as well as an enlarged right mandibular lymph node. Care of the dog was transferred to the Dentistry and Oral Surgery Service. Intraoral radiographs were obtained (Figure 1).
Dental images of an anesthetized 2.5-year-old 38.5-kg intact male German Shepherd Dog was referred to a veterinary medical teaching hospital because of oral pain and difficulty opening its mouth. A—There are gingival parulides associated with the right mandibular fourth premolar and first molar teeth. There is intrinsic staining associated with the right mandibular canine, fourth premolar, and first molar teeth. B—Intraoral radiographic image (obtained with a parallel technique) of the right mandibular first molar tooth and adjacent teeth.
Citation: Journal of the American Veterinary Medical Association 262, 3; 10.2460/javma.23.11.0648
Formulate differential diagnoses, then continue reading.
Diagnostic Imaging Findings and Interpretation
Intraoral radiography of the caudal right mandible revealed areas of osteolysis and osseous proliferation extending from the level of the right mandibular third premolar tooth to the most caudal extent of the mandible visible on radiographs. The mandibular canal was indistinct ventral to the right mandibular first molar. There was alveolar bone loss in the furcation of the right mandibular second molar tooth, and there was a periapical lucency consistent with endodontic disease of the right mandibular second molar tooth (Figure 2). In addition, there was an area of more radiopaque bone, surrounded by a lucent region on the ventral mandible, consistent with a sequestrum. Computed tomography (SOMATOM Force; Siemens Medical Solutions USA Inc) images were obtained to evaluate the extent of the sequestrum (Figure 3). Computed tomography revealed that not only was there a sequestrum on the ventral cortex of the mandible, the sequestrum extended to the lingual aspect of the mandible. In addition, CT images revealed that the periosteal reaction was identified to the most caudal extent of the mandible, the angular process.
Same radiographic image as in Figure 1. There is osseous proliferation along the mandibular cortex (white arrow). There is an area of sclerotic bone surrounded by lucency, consistent with a sequestrum (black arrow). There is periapical lucency associated with the right mandibular second molar tooth (stars).
Citation: Journal of the American Veterinary Medical Association 262, 3; 10.2460/javma.23.11.0648
Transverse (A) and sagittal (B) plane CT images of the skull of the same dog in Figure 1 obtained at the level of the mandibular sequestrum. Sclerotic bone is visible, not only on the ventral mandibular cortex (white arrow), but also extending up onto the lingual aspect (black arrow). Computed tomography images also reveal that the periosteal changes extend further caudally than is possible to identify on the radiographic images (star). The images are displayed in a bone window (window width, 2,500 HU; window level, 400 HU) with a 2.0-mm slice thickness.
Citation: Journal of the American Veterinary Medical Association 262, 3; 10.2460/javma.23.11.0648
Treatment and Outcome
There was no obvious cause for the suspected osteomyelitis lesion in the dog, so the surgical plan was created to extract the affected teeth, remove sequestrum, and obtain adequate samples for biopsy and cultures. In brief, a mucoperiosteal flap was elevated to facilitate surgical extraction of the right mandibular fourth premolar tooth and first, second, and third molar teeth. Following extraction of the teeth, mucogingival flaps were extended and a well-demarcated line of transition between superficial yellow, friable, relatively avascular abnormal bone and white and vascular bone was identified. The abnormal and normal bone was separated by a thin line of fibrous tissue. The avascular bone was removed using periosteal elevators and a 701L bur on a high-speed dental handpiece. A portion was submitted for histopathology and another for aerobic and anaerobic culture. Cultures for fungal growth were also submitted. The site was copiously lavaged with sterile saline. The periosteum, which was thickened, was released with scissors to facilitate tension-free closure with 4-0 poliglecaprone suture (Monocryl; Ethicon Inc).
The dog was discharged from the hospital with a fentanyl transdermal patch (100 µg/h), and the owner was instructed to continue enrofloxacin, amoxicillin–clavulanic acid, and deracoxib.
Histopathology revealed chronic suppurative osteomyelitis with osteonecrosis, osteoproliferation, osteolysis, granulation, and fibrosis. Aerobic and anaerobic culture of the right mandible yielded moderate growth of Pseudostreptococcus spp, Bacterioides spp, and Fusobacterium spp and mild growth of Escherichia coli and Enterococcus spp. There was no evidence of fungal growth. The antibiotics were continued for a month after surgery to treat the deep bacterial infection.
Three months after surgery, the dog presented for recheck and evaluation for a possible total pulpotomy and root canal therapy of the intrinsically stained right mandibular canine tooth. Upon presentation, the owner reported that the dog had been doing well at home and finished the course of antimicrobials. The dog was anesthetized, and a complete oral examination and intraoral radiographs revealed a right mandible with no additional evidence of osteomyelitis, though it remained thickened (Figure 4).
Radiographic image from the same dog in Figure 1, 3 months after the original surgery. While there is still thickening of the mandible and it’s not possible to visualize the mandibular canal because of increased radiopacity (white arrow), the radiographic appearance is no longer associated with aggressive lytic lesions.
Citation: Journal of the American Veterinary Medical Association 262, 3; 10.2460/javma.23.11.0648
Comments
In this report, dental radiography of the dog led to a diagnosis of a mixed proliferative and lytic osseous lesion of the right mandible. While osteomyelitis was the primary differential, a neoplastic lesion could not be ruled out without biopsy. In this case, CT in addition to dental radiography was critical in identifying the extent of the sequestrum. Because of the location on the lingual portion of the mandible, that sequestrum was not possible to appreciate on radiographs.
Osteomyelitis is inflammation of bone and periosteum and is characterized by the mix of proliferative and lytic radiographic lesions.1,2 Osteomyelitis is rarely reported in the oral cavity and may have fungal or bacterial causes.3 These causative agents may be introduced by penetrating injuries; secondary to periodontal disease, trauma, chronic infections, migrating plant material, or previous surgeries; or idiopathic.1 No cause of osteomyelitis was ever identified in this case. A sequestrum forms when a piece of bone is separated from the large osseous structure; in this case, the mandible. Radiographically, it can appear as an area of more radiopaque bone surrounded by lucency. Sequestra have a more typical appearance on CT, with a more sclerotic area of bone surrounded by lucency. In addition, the extent of the sequestra is more easily identifiable with 3-D imaging. The CT was also able to identify that the inflammation extended onto the angular process, which was most likely contributing to the patient’s reluctance to open its mouth due to the attachments of the muscles of mastication in that location.
The dog of this report had 3 intrinsically stained teeth on the ipsilateral side of the osteomyelitis and the right mandibular canine, fourth premolar, and first molar teeth. Pulpitis causes intrinsic staining in teeth.4 If not reversible, pulpitis leads to pulp necrosis requiring either root canal therapy or extraction.5 Pulpitis can be caused by trauma, or anachoresis, which was suspected in this case because the canine tooth was not directly associated with the osteomyelitis lesion in the right mandible and the lesion directly affected the mandibular canal. The right mandibular fourth premolar and first molar teeth were extracted because of the associated parulides. The pulpitis associated with the mandibular canine tooth appeared to have resolved at the time of the recheck radiographic examination.
Acknowledgments
None reported.
Disclosures
The authors have nothing to disclose. No AI-assisted technologies were used in the generation of this manuscript.
Funding
The authors have nothing to disclose.
References
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