Whole-body computed tomography patterns of dystrophic and metastatic soft-tissue calcification in dogs: a multicenter retrospective study.

IMPORTANCE: Differentiating between dystrophic and metastatic soft tissue calcifications in dogs is clinically essential but remains diagnostically challenging. OBJECTIVE: This retrospective study aimed to categorize canine soft tissue calcifications on whole-body computed tomography (CT) based on anatomical location and pattern, determine if CT can differentiate between metastatic and dystrophic types based on these factors, and identify pattern tendencies within dystrophic subtypes. METHODS: Calcifications were classified into group 1 (dystrophic) and group 2 (metastatic). Multivariable generalized estimating equation (GEE) logistic regression identified variables independently associated with metastatic calcification. Group 1 was subdivided into 1a (with mass) and 1b (without mass) to assess pattern tendencies across organs. RESULTS: Organ location alone was not independently associated with calcification type. Instead, similar organ-specific patterns were observed across etiologic groups, indicating substantial topographic overlap; both groups 1b and 2 predominantly exhibited round/oval multifocal patterns in kidneys, and curvilinear/rim diffuse patterns in the vasculature. Conversely, group 1a showed a higher propensity for amorphous/irregular patterns within masses. In multivariable GEE analysis, focal distribution was significantly associated with metastatic calcification (adjusted odds ratio [OR], 1.18; 95% confidence interval [CI], 1.02-1.37; p = 0.029) compared to multifocal distribution, while curvilinear/rim shapes showed a curvilinear/rim shape was not significantly associated with metastatic calcification after adjustment (OR, 1.26; 95% CI, 0.98-1.63; p = 0.072) compared to round/oval shapes. CONCLUSIONS AND RELEVANCE: Whole-body CT effectively categorizes the locations and patterns of canine soft tissue calcifications and identifies distinct tendencies within dystrophic subtypes. However, due to significant organ-specific topographic overlaps, CT imaging alone is insufficient to definitively differentiate metastatic from dystrophic calcifications, necessitating comprehensive clinical and biochemical correlation.