Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 19 Mar 2023

Heterotopic Ossification of the Soft Tissues Overlying the Carpal Bones of a 2-year-old Bearded Dragon (Pogona vitticeps)

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Page Range: 96 – 100
DOI: 10.5818/JHMS-D-22-00044
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Abstract

A 2-yr-old female bearded dragon (Pogona vitticeps) presented to the clinic exhibiting lameness and significant swellings bilaterally in the carpal region. On physical examination the lizard was determined to be in obese body condition and pododermatitis was observed on the palmar aspects of both carpi. The rest of the examination was unremarkable. Radiographs revealed opacities present in both carpal joints with possible fluid accumulation. Biochemistry revealed hypercalcemia and hyperphosphatemia. A joint aspirate was performed and submitted for cytology and culture. The sample was sterile and only inflammatory cells were seen. Despite these results, the swelling initially improved with daily lincomycin 5 mg/kg intramuscularly (IM) but recurred after 1 month, and the lizard was referred to a specialist center for further investigations. A tissue biopsy was performed and submitted for histology and culture. Histopathologic examination revealed periarticular soft tissue ectopic bone characterized by a proliferation of ectopic cartilage and both lamellar and woven bone with hematopoietically active bone marrow within a fibrous connective tissue stroma. Bacterial culture revealed a scant growth of Staphylococcus aureus and Serratia marcescens. The lizard received ceftazidime 20 mg/kg every 72 h IM for 3 wk. Clinical signs resolved until 8 months later when the swellings returned.

Figure 1.
Figure 1.

Swelling of the right carpal joint in a bearded dragon (Pogona vitticeps) with a central focal callus.


Figure 2.
Figure 2.

Conscious dorsoventral radiograph of a bearded dragon (Pogona vitticeps). A radiopaque area is visible in the left carpal region.


Figure 3.
Figure 3.

Heterotopic ossification, bearded dragon (Pogona vitticeps). Hematoxylin and eosin. (A) Mature fibrous connective tissue blending with proliferative ectopic bone and cartilage. Bar = 500 µm. (B) Lamellar bone (arrow) surrounded by mature fibrous connective tissue (asterisk). Associated with the lamellar bone are low numbers of osteoclasts (arrowheads). Bar = 100 µm. (C) Proliferation of ectopic cartilage with chondrocytes within lacunae. Bar = 50 µm. (D) Hematopoietically active bone marrow with a moderately increased number of intramedullary heterophils (arrows). Bar = 50 µm.


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