Diagnostic Imaging In Veterinary Dental Practice

Boaz Arzi Dentistry and Oral Surgery Service, William B. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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Nadine Fiani Dentistry and Oral Surgery Service, William B. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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History and Physical Examination Findings

A 5-year-old 4.4-kg (9.7-lb) castrated male Himalayan cat was evaluated because of a mass involving the rostral portions of the mandibles. The cat had been adopted at an early age, and the medical history was unremarkable. The cat was reportedly otherwise healthy and showed no signs of pain or difficulties with prehension or mastication. The owner reported first noticing the mass 2 weeks earlier.

Results of a general physical examination were unremarkable. Extraoral examination revealed a 15 × 10 × 10-mm well-circumscribed, firm mass involving the rostral portion of the right mandible; signs of pain were not evident during palpation of the mass. Oral examination revealed mild plaque and calculus, mild gingivitis, and discoloration of the right mandibular canine tooth with axial mobility and partial extrusion. There was 4 mm of gingival recession and a 2-mm area of ulceration at the buccal aspect of the right mandibular canine tooth.

Results of a CBC, serum biochemical profile, and urinalysis were within reference limits. The cat was anesthetized, and intraoral radiography, periodontal charting, and intraoral incisional biopsy were performed. Selected radiographic views are provided (Figure 1).

Figure 1—
Figure 1—

Occlusal radiographic view of the rostral portions of the mandibles (A) and lateral radiographic views of the right (B) and left (C) mandibular canine teeth in a cat examined because of a mass involving the rostral portions of the mandibles.

Citation: Journal of the American Veterinary Medical Association 235, 10; 10.2460/javma.235.10.1149

Determine whether additional studies are required, or make your diagnosis, then turn the page

Diagnostic Imaging Findings and Interpretation

Oral radiography revealed permeative bone loss involving the rostral portions of both mandibles but mainly involving the area of the right mandibular canine tooth, extrusion of the right mandibular canine tooth, and endosteal scalloping at the mandibular canals of both mandibles, extending from the mandibular canine teeth to the level of the mandibular third premolar teeth (Figure 2). There was a sunburst-like periosteal reaction at the interdental space of the right mandibular third premolar tooth and right mandibular canine tooth. In addition, there was 1 mm of horizontal bone loss at the right and left mandibular premolar and molar teeth and near total loss of attachment at the right maxillary third incisor tooth.

Figure 2—
Figure 2—

Same radiographic views as in Figure 1. On the occlusal radiographic view (A), notice the permeative bone loss (arrows). On the lateral radiographic view of the right mandibular canine tooth (B), there is near-total loss of attachment (arrows), extrusion of the right mandibular canine tooth, and a sunburst-like periosteal reaction at the interdental space of the right mandibular third premolar tooth and right mandibular canine tooth. On the lateral radiographic view of the left mandibular canine tooth (C), there is evidence of endosteal scalloping to the level of the mandibular third premolar tooth (arrows).

Citation: Journal of the American Veterinary Medical Association 235, 10; 10.2460/javma.235.10.1149

A permeative pattern of bone destruction is identified as a pattern of uniform, tiny, poorly marginated, oval or linear radiolucencies.1 Pathophysiologically, the lesion represents an exaggerated remodeling response, with less bone being laid down overall than is being absorbed.1 This radiologic pattern represents an aggressive, fast-growing lesion such as osteomyelitis or neoplasia.1 In addition, endosteal scalloping, as observed in this cat, may represent the earliest radiographic appearance of a neoplastic lesion within a bony cavity.1 Differential diagnoses that were considered for the oral mass in this cat included osteomyelitis, nonodontogenic tumors (eg, squamous cell carcinoma), and odontogenic tumors (eg, ameloblastoma).

Treatment and Outcome

All teeth were ultrasonically scaled above and below the gingival margin and air-polished. The right mandibular canine tooth was surgically extracted because it was discolored and mobile. The right maxillary third incisor tooth was extracted because of advanced periodontitis. Three biopsy specimens were obtained from tissue surrounding the alveolus of the right mandibular canine tooth and the enlarged rostral portions of the mandibles and submitted for histologic examination and aerobic and anaerobic bacterial culture and susceptibility testing.

Histologic examination of the biopsy specimens revealed severe suppurative and lymphoplasmacytic osteomyelitis with evidence of bone lysis and woven bone formation. There was no evidence of neoplasia in any of the sections. No bacterial organisms were seen during examination of direct smears of the biopsy specimens, and aerobic and anaerobic bacterial culture yielded only low numbers of mixed bacterial organisms that likely represented the normal oral flora.

The cat was treated with clindamycin (50 mg, PO, q 24 h) for 30 days and buprenorphine (0.1 mg, PO, q 12 h) for 4 days, and the owner was instructed to rinse the cat's oral cavity with chlorhexidine gluconate solution twice a day for 10 days.

During a recheck examination 3 months later, the cat was bright, alert, and responsive, and the owner reported that the cat was doing well at home. The rostral mandibular mass had resolved, and the gingival appearance was normal. The oral mucosa was intact, and there was no clinical evidence of recurrence of the mass. The owner declined general anesthesia. Therefore, recheck dental radiography was not performed.

Comments

Osteomyelitis is defined as inflammation, but not necessarily infection, of the bone and bone marrow.2 In dogs and cats, osteomyelitis is most commonly caused by bacterial infection but may also be a result of fungal infection or a reaction to metallic implants.3 Bacteria may gain access to the mandible as a result of trauma, surgical intervention, or periodontal lesions; as a result of extension of soft tissue infection or hematogenous spread; or through nonvital teeth. The number and pathogenicity of the bacteria involved in conjunction with the affected animal's resistance factors determine the clinical appearance, extent of the inflammatory process, and speed with which infection develops.2,4–6 The mandibles are the most commonly infected bones in cats after the radius and ulna and may become infected with gram-positive bacteria, gram-negative bacteria, or a mixture of aerobic and anaerobic bacteria.4 Acute osteomyelitis often responds to appropriate antimicrobial treatment.7,8 However, most cases of osteomyelitis seen in veterinary practice are chronic at the time of diagnosis, and treatment may necessitate surgery, collection of biopsy specimens, debridement, bone grafting, and stabilization of bone in addition to prolonged antimicrobial administration.4,8 In the cat described in the present report, the source of infection was not identified but likely was a result of invasion of the mandibles by normal oral bacterial flora secondary to endodontal or periodontal disease.9 Resolution of the infection following extraction of the right mandibular canine tooth and antimicrobial treatment suggests a dental cause of the infection.

The cat described in the present report did not have any of the common clinical signs typically associated with osteomyelitis, such as excessive salivation, oral bleeding, halitosis, anorexia, and difficulties with prehension or mastication.9 The unusual clinical appearance and radiographically aggressive appearance of this lesion were initially suggestive of a neoplastic process, and histologic examination of biopsy specimens was the key diagnostic tool in determining the true nature of the lesion. Radiography was important, however, in showing the need for biopsy. This is in agreement with the findings of Kapatkin et al,9 who found that the diagnosis in cats with mandibular swellings should be based on results of oral radiography coupled with results of histologic examination.

References

  • 1.

    Dobson H, Friedman L. Radiologic interpretation of bone. In: Fackelman G, ed. Bone in clinical orthopedics. New York: AO Publishing, Thieme, 2002;175200.

    • Search Google Scholar
    • Export Citation
  • 2.

    Regezi JA, Sciubba JJ, Jordan RC. Inflammatory jaw lesions. In: Regezi J, Sciubba JJ, Jordan RC, eds. Oral pathology: clinical pathologic correlation. 4th ed. St Louis: Saunders, 2003;309320.

    • Search Google Scholar
    • Export Citation
  • 3.

    Harari J. Osteomyelitis. J Am Vet Med Assoc 1984;184:101102.

  • 4.

    Muir P, Johnson KA. Anaerobic bacteria isolated from osteomyelitis in dogs and cats. Vet Surg 1992;21:463466.

  • 5.

    Griffiths GL, Bellenger CR. A retrospective study of osteomyelitis in dogs and cats. Aust Vet J 1979;55:587591.

  • 6.

    Walker RD, Richardson DC, Bryant MJ, et al.Anaerobic bacteria associated with osteomyelitis in domestic animals. J Am Vet Med Assoc 1983;182:814816.

    • Search Google Scholar
    • Export Citation
  • 7.

    Caywood DD, Wallace LJ, Braden TD. Osteomyelitis in the dog: a review of 67 cases. J Am Vet Med Assoc 1978;172:943946.

  • 8.

    Johnson KA, Lomas GR, Wood AK. Osteomyelitis in dogs and cats caused by anaerobic bacteria. Aust Vet J 1984;61:5761.

  • 9.

    Kapatkin AS, Manfra Marretta S, Patnaik AK, et al.Mandibular swellings in cats: prospective study of 24 cats. J Am Anim Hosp Assoc 1991;27:575580.

    • Search Google Scholar
    • Export Citation

Contributor Notes

Address correspondence to Dr. Arzi (barzi@ucdavis.edu).
  • Figure 1—

    Occlusal radiographic view of the rostral portions of the mandibles (A) and lateral radiographic views of the right (B) and left (C) mandibular canine teeth in a cat examined because of a mass involving the rostral portions of the mandibles.

  • Figure 2—

    Same radiographic views as in Figure 1. On the occlusal radiographic view (A), notice the permeative bone loss (arrows). On the lateral radiographic view of the right mandibular canine tooth (B), there is near-total loss of attachment (arrows), extrusion of the right mandibular canine tooth, and a sunburst-like periosteal reaction at the interdental space of the right mandibular third premolar tooth and right mandibular canine tooth. On the lateral radiographic view of the left mandibular canine tooth (C), there is evidence of endosteal scalloping to the level of the mandibular third premolar tooth (arrows).

  • 1.

    Dobson H, Friedman L. Radiologic interpretation of bone. In: Fackelman G, ed. Bone in clinical orthopedics. New York: AO Publishing, Thieme, 2002;175200.

    • Search Google Scholar
    • Export Citation
  • 2.

    Regezi JA, Sciubba JJ, Jordan RC. Inflammatory jaw lesions. In: Regezi J, Sciubba JJ, Jordan RC, eds. Oral pathology: clinical pathologic correlation. 4th ed. St Louis: Saunders, 2003;309320.

    • Search Google Scholar
    • Export Citation
  • 3.

    Harari J. Osteomyelitis. J Am Vet Med Assoc 1984;184:101102.

  • 4.

    Muir P, Johnson KA. Anaerobic bacteria isolated from osteomyelitis in dogs and cats. Vet Surg 1992;21:463466.

  • 5.

    Griffiths GL, Bellenger CR. A retrospective study of osteomyelitis in dogs and cats. Aust Vet J 1979;55:587591.

  • 6.

    Walker RD, Richardson DC, Bryant MJ, et al.Anaerobic bacteria associated with osteomyelitis in domestic animals. J Am Vet Med Assoc 1983;182:814816.

    • Search Google Scholar
    • Export Citation
  • 7.

    Caywood DD, Wallace LJ, Braden TD. Osteomyelitis in the dog: a review of 67 cases. J Am Vet Med Assoc 1978;172:943946.

  • 8.

    Johnson KA, Lomas GR, Wood AK. Osteomyelitis in dogs and cats caused by anaerobic bacteria. Aust Vet J 1984;61:5761.

  • 9.

    Kapatkin AS, Manfra Marretta S, Patnaik AK, et al.Mandibular swellings in cats: prospective study of 24 cats. J Am Anim Hosp Assoc 1991;27:575580.

    • Search Google Scholar
    • Export Citation

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