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- Radiographic Discovery: Os Clitoridis Common in Female Ferrets—Normal, Not Pathologic
Radiographic Discovery: Os Clitoridis Common in Female Ferrets—Normal, Not Pathologic
VRU 2025
Obi Veterinary Education
November 15, 2025
Annalisa Wager, Silke Hecht, Emi Knafo, Danielle Tarbert, Robert Reed, Xiaocun Sun
Background
The os clitoridis (baubellum) is an underrecognized bone within the clitoris, documented in certain mammalian taxa but poorly characterized in veterinary species. In ferrets, its presence has been inconsistently reported, and it is absent from most diagnostic imaging references. Misinterpretation as a urethral calculus or foreign body is possible. This study aimed to describe the prevalence and radiographic morphology of the os clitoridis in female domesticated ferrets and to evaluate associations with age, reproductive status, and adrenal disease.
Methods
This retrospective study reviewed digital abdominal radiographs from 2005–2024 at the University of Tennessee College of Veterinary Medicine. Female ferrets with diagnostic-quality images including the perineal region were included. Age, spay status, and adrenal disease status were extracted from records. Radiographs were evaluated for presence, size, and shape of the os clitoridis. Statistical analyses (chi-square, logistic regression, ANOVA) assessed correlations with age, reproductive status, and adrenal disease, with significance at p < .05.
Results
Sixty-six ferrets (37 intact, 29 spayed) met inclusion criteria (median age 39.5 months; range 2–118 months). An os clitoridis was present in 49/66 (74.2%) ferrets, appearing as punctate (n=10), linear (n=22), or curvilinear (n=17) mineral opacities on lateral radiographs. Mean length was 3.06 ± 1.20 mm and mean width 0.68 ± 0.18 mm. Presence was significantly more common in intact (p = .0229) and older (p = .0145) ferrets. Width was greater in spayed than intact ferrets (p = .0171). No association was found between os clitoridis presence or size and adrenal disease (p > .2). Two cases were initially misdiagnosed radiographically as urethral calculi.
Limitations
As a retrospective study, data completeness varied, and some clinical details were unavailable. Hormone levels were inconsistently recorded, limiting correlation with endocrine function. Genetic influences and geographic variations were not investigated, and no histopathologic confirmation was possible. The sample represented a single regional population, which may limit generalizability.
Conclusions
The os clitoridis is a common, normal anatomic finding in female ferrets and appears in approximately three-quarters of individuals. It presents as a small mineralized structure in the perineal region on radiographs, with morphology influenced by age and hormonal status. Recognizing this feature is critical to avoid misinterpretation as a urogenital abnormality. Future studies incorporating hormonal and genetic data could further elucidate its developmental biology.
Lateral radiographs of the perineal region in 8 different female ferrets. (A, B) Large os clitoridis (circle) in a 3-year-old female intact (A) and a 2-year-old female spayed (B) ferret. (C, D) Medium-sized os clitoridis (circle) in a 6-year-old female intact (C) and a 1-year-old female spayed (D) ferret. (E, F) Small/punctate os clitoridis (circle) in a 2-year-old (E) and a 7-year-old (F) female spayed ferret. Note that an os clitoridis of this size could be confused with a urethrolith. (G, H) 5-year-old female intact (G) and 5-year-old female spayed (H) ferrets without a visible os clitoridis.
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