Computed tomographic features of renal neoplasms in dogs: introduction of the collateral vessel sign in veterinary medicine

Objective To assess the role of CT in detecting canine renal neoplasms and describe their imaging features. Methods 32 dogs with histologically and cytologically confirmed renal tumors were included. Computed tomography scans were reviewed for qualitative parameters: lesions number, size, margins, enhancement pattern, mineralization, laterality, intrarenal location, hemorrhage, lymphadenopathy, pulmonary metastases and collateral vessels. Quantitative parameters included lesion diameter and pre- and postcontrast attenuation. Data distribution was tested with the Shapiro-Wilk test, and intergroup differences were evaluated using the Fisher exact test. Results Diagnoses comprised primary renal tumors—renal cell carcinoma (RCC; 12 of 32), sarcoma (2 of 32), hemangiosarcoma (1 of 32), primary lymphoma (1 of 32), and cystic adenoma (1 of 32)—as well as multicentric lymphoma (ML; 5 of 32) and metastatic lesions (10 of 32). Primary tumors were mainly unilateral masses, whereas ML and metastases appeared as bilateral nodules. Collateral vessels were significantly more frequent in RCC than in ML or metastases and were also associated with mass lesions rather than nodular lesions. Multicentric lymphoma showed more homogeneous postcontrast enhancement than primary tumors. Conclusions CT provides key information to differentiate canine renal tumor types. Collateral vessels may indicate RCC and are more prevalent in mass lesions; therefore, they should be considered in surgical planning. Canine lymphoma showed CT features consistent with human reports, although overlap among tumor subtypes reduced specificity. Clinical Relevance This study describes novel tomographic features of canine renal neoplasia and comprehensively summarizes their CT characteristics, aiding diagnosis and treatment planning.