History and Physical Examination Findings

A 9-year-old 6.9 kg castrated male Ragdoll cat was presented to the veterinary clinic for a scheduled routine annual examination. The owner reported that the patient was otherwise healthy. On physical examination, the patient was overweight (body condition score 7/9) with left-side mandibular swelling. Oral examination revealed gingival hyperemia and moderate dental plaque. Further dental examination and radiographs under anesthesia were warranted. Pre-anesthetic CBC and coagulation panel (prothrombin time test and activated partial thromboplastin test) were unremarkable. Serum biochemistry revealed mild hypercholesterolemia (230 mg/dL; reference interval, 75 to 220 mg/dL). The patient was sedated and anesthetized with midazolam (0.2 mg/kg, IV), buprenorphine (0.02 mg/kg, IV), and alfaxalone (1 mg/kg, IV). To contribute to multi-modal pain management, 0.18 mL of Bupivacaine 0.5% and 0.02 mL Buprenorphine (0.3 mg/mL) were instilled at the left middle mental (rostral mandibular) nerve block site. Oral examination and radiographic views evidenced a swelling at the lower right mandible, surrounding the 304 canine tooth and the adjacent 303 incisor tooth (Figure 1). Clinically, the lesion appeared as a 1 cm, raised, rounded, firm mandibular swelling at the left rostral chin, ventral to 304 canine tooth. The 304 canine tooth was discolored (yellow) with dark calculus at the sulcus; erythema and mild hyperplastic gingiva leading to 0.4 to 0.5 cm pocketing circumferentially. The 303 incisor tooth adjacent to this canine was mobile and coronally displaced as well.

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Dorsoventral intraoral rostral mandibular radiographic views before (A) and after (B) 303 and 304 teeth extraction in a 9-year-old 6.9-kg castrated male Ragdoll cat presented to the veterinary clinic with a left-side mandibular swelling. R =Right radiographic positional marker. L = Left radiographic positional marker.

Citation: Journal of the American Veterinary Medical Association 262, 10; 10.2460/javma.24.06.0388

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Diagnostic Imaging Findings and Interpretation

Radiographs evidenced the marked bucco-distal proliferation of rarified bone with a mottled appearance, vertical areas of alveolar bone loss that appeared as a widened periodontal ligament space, and resorption of tooth 304 and 303 (Figure 2). Additionally, there was complete resorption of the 107, 207, 308, and 408 teeth. The 304 and 303 teeth were extracted. Core biopsy samples were obtained by sampling 0.2 cm pieces of the abnormal and heterogeneous alveolar bone and placed in fixed in neutral buffered 10% formalin and routinely processed for histologic examination. Histologically the submucosa was expanded by thick hypereosinophilic collagen with occasional islands of bone. There were scattered reactive woven bone trabeculae lined by a single layer of hypertrophic osteoblasts and separated by thick fibro-collagenous tissue. The submucosa was expanded by infiltrating areas of fibro-osseous proliferation and granulation tissue amid variable numbers of neutrophils, lymphocytes, and plasma cells. The intertrabecular spaces were expanded by myxomatous loose fibro-collagenous stroma (Figure 3). One sample of macerated tissue was submitted for bacterial (aerobic and anaerobic) culture. The radiographic and histologic findings were consistent with the diagnosis of feline alveolar bone expansion, osteomyelitis, and tooth resorption.

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The same radiographic views as in Figure 1. A—There was a marked bucco-distal proliferation of rarified bone with a mottled appearance, vertical areas of alveolar bone loss that appeared as a widened periodontal ligament space, and resorption of tooth 304 and 303 (arrowheads). B—Marked bulbous alveolar bone expansion (arrowheads). The canine tooth 304 and the incisor tooth 303 were extracted, and the extraction site was covered with a gingival flap.

Citation: Journal of the American Veterinary Medical Association 262, 10; 10.2460/javma.24.06.0388

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Photomicrographs of sections from the core biopsies from the remnants of the alveolar bone from 304 tooth lesions are described in Figures 1 and 2. A—The intertrabecular spaces were expanded by myxomatous loose fibrocollagenous stroma (asterisks). H&E stain; bar = 200 μm. B—Variable numbers of neutrophils, lymphocytes, and plasma cells (arrowhead) infiltrated the intertrabecular spaces lining the bone trabeculae. H&E stain; bar = 50 μm.

Citation: Journal of the American Veterinary Medical Association 262, 10; 10.2460/javma.24.06.0388

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Treatment and Outcome

The 303 and 304 teeth were extracted, and the extraction site was covered by creating a gingival flap, gently elevating from the subgingival bone with periosteal elevators. Anaerobic bacterial culture yielded a light growth of Bacteroides species after 5 days. Aerobic culture did not yield bacterial growth. A single dose of Convenia (cefovecin; 8 mg/kg, SC) was administered during anesthetic recovery and the patient was discharged on gabapentin (4.5 to 10 mg/kg, PO, q 8 to 12 h) for 7 days for post-operative pain control. The patient was placed on clindamycin (5.5 mg/kg, PO, q 12 h) for 2 weeks. At the next physical examination, 7 months post-procedure, showed that the jaw swelling had completely resolved with full healing of the dental extraction and biopsy site and no further gingivitis or gross evidence of dental disease.

Comments

Feline alveolar bone expansion and osteomyelitis is a syndrome recognized in cats, with several synonyms in the veterinary literature including feline buccal bone expansion, peripheral buttressing, and alveolar or peripheral osteitis.^1–4 The maxillary canine teeth are more commonly affected than mandibular canine teeth (like the case presented herein), maxillary and mandibular premolar and molar teeth, and the condition is characterized by firm, bulbous, and smooth proliferation of the buccal aspect of the alveolar bone, along with gingivitis, root exposure, or tooth extrusion.^1–4 This syndrome represents a cause of tooth loss in cats.³ Periodontitis, gingivitis, gingival recession, periodontal pocket detecting during probing, and tooth resorption or extrusion are usually concomitant with this syndrome.^1,2,4 Periodontitis is usually considered a common feline oral lesion^2,4,5 and alveolar bone expansion was identified in 53% of the cats with this condition in a retrospective study.⁵

Alveolar bone expansion is a common syndrome diagnosed in home-owned cats during dental examination.³ A retrospective study described the presence of alveolar bone expansion in at least 1 canine tooth in 35% of the animals (34 of 97), and its presence did not differ significantly among the different sexes, ages, body weights, or breeds.³ Reported clinical signs include ptyalism, oral pain, and incomplete occlusion.⁴

The most important radiographic findings in feline alveolar bone expansion and osteomyelitis are the rarifying osseous proliferation, reported in 96% of the cases in a retrospective study, followed by tooth resorption (83% of the cases).² The expansion of the alveolar bone is considered within a radiographic view when the alveolar bone surrounding the canine tooth has an expanded bulbous appearance rather than the normal coronally straight line.³ The expanded bulbous alveolar bone appears mottled suggesting the presence of rough and large bone trabeculae.⁴ Other radiographic findings described in cases of this syndrome include vertical alveolar bone loss, evidenced by a widened periodontal ligament space and loss or extrusion of the tooth.^3,5

The presence of woven bone, mixed inflammation composed of plasma cells, lymphocytes, and neutrophils within the loose fibrous tissue, and a myxomatous fibrous intertrabecular stroma are histologic lesions reported in alveolar bone expansion and osteomyelitis.^1,2 In some cases, ulceration and erosion of the gingival mucosa are present with the proliferation of granulation tissue and suppurative inflammation.²

The pattern of alveolar expansion is more prominent in the canine teeth when compared to molar or premolar teeth, and it is speculated that mechanical forces during translation and intrusion of the teeth cause major compression on the alveolar bone leading to degeneration of the periodontal ligament, inflammation, and tooth resorption.² The periodontal ligament involvement is secondary to the inflammatory process within the alveolar bone, due to previous evidence of a lack of inflammatory changes in the periodontal ligament in cases of alveolar osteomyelitis.²

The main differential diagnosis for osteolytic and osteoproliferative diseases in the oral cavity of cats is squamous cell carcinoma.⁴ Benign tumors with bone production like ossifying fibroma and osteoma should be considered in cases of alveolar bone expansion from the canine teeth.² In caudal alveolar osteomyelitis, other differential diagnoses include squamous cell carcinoma and feline chronic gingivostomatitis.² Histopathology is required for the definitive diagnosis of these lesions.^2,4

Normal oral microbiota bacteria are isolated from osteomyelitis cases and the therapy implies the use of surgical debridement, osteoplasty of alveolar bone, full-thickness mucoperiosteal flap, antibiotics, and pain management.^2,4 However, bacterial cultures have to be interpreted cautiously, since normal microbiota can be isolated without the implication of osteomyelitis. In this case report the culture isolate results were interpreted in conjunction with the histopathological and imaging findings. Since alveolar bone expansion develops in conjunction with periodontal disease, this condition can be prevented through regular professional dental care and adequate oral hygiene.⁴

Disclosures

Jorden Manasse and Tatiane Terumi Negrão Watanabe are employed by Antech Diagnostics, Mars Petcare Science & Diagnostics, and they declare that no financial support was received for the research, authorship, and/or publication of this article. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

No AI-assisted technologies were used in the generation of this manuscript.

Funding

The authors have nothing to disclose.

ORCID

D. Barrantes Murillo https://orcid.org/0000-0002-0744-3774