Computed tomographic characterization and prevalence of osseous cyst-like lesions in the mandibular condylar process of dogs.

Abstract

BACKGROUND: Osseous cyst-like lesions (OCLLs) in the mandibular condylar process of dogs are rare and generally considered clinically not relevant, although have been associated with osteoarthritis (OA). On computed tomography (CT) scans, OCLLs appear circular in shape but may change with the cutting plane. This retrospective study aimed to investigate the CT characteristics of OCLLs and their prevalence in the mandibular condylar process of dogs. RESULTS: A total of 716 CT scans of dogs examined from 2018 to 2025 (1,432 joints), met the inclusion criteria; 385 males and 331 females, of different breeds, aged 1 month to 17 years. OCLLs were observed in 57 dogs, 31 in the head of the condylar process (CH) and 26 in the neck of the condylar process (CN), with 4 dogs with OCLLs in both positions. OCLLs appeared as circular images in the transverse planes in all dogs but had a concave shape resembling a bone notch in the dorsal and sagittal planes, and in three-dimensional volume rendering (3DVR). In the CH, OCLLs were associated with OA in 19 out of 24 joints. Brachycephalic breeds were affected more frequently, primarily due to the high proportion of French Bulldogs that showed a highly significant association with CH OCLLs (P = 0.0009; OR: 14.82; two-sided Fisher's exact test). In the CN, OCLLs were significantly associated with male dogs of mesocephalic breeds (P = 0.0164; OR: 2.96; two-sided Fisher's exact test). CONCLUSIONS: CT dorsal and sagittal planes, and 3DVR allowed us to identify the notch shape of OCLLs. OCLLs in the CH are uncommon in dogs and French Bulldogs would appear to be predisposed. OA signs are observed in a high proportion in dogs with OCLLs suggesting a potential association.