Plasma Dimethylarginine Concentrations in Dogs With Large Cell Lymphoma or Hemangiosarcoma: A Prospective Observational Study

Asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) are endogenous methylated arginine derivatives associated with endothelial dysfunction and tumour progression in humans. Their relevance in canine oncology remains unclear. This prospective study aimed to assess plasma concentrations of ADMA and SDMA in dogs newly diagnosed with large cell lymphoma or non-cutaneous hemangiosarcoma (HSA); dogs with benign splenic lesions were also enrolled. Renal function was assessed at the time of inclusion to exclude overt kidney disease. Plasma ADMA and SDMA concentrations were measured at diagnosis, and clinical staging data were collected. A total of 31 dogs were enrolled: 11 with lymphoma, 15 with HSA and 5 with benign splenic lesions. SDMA concentrations exceeded the reference interval in 47%, 36% and 0% of dogs with HSA, lymphoma and benign lesions, respectively. Dogs with lymphoma (p = 0.003) and HSA (p = 0.013) had significantly higher SDMA concentrations than dogs with benign splenic lesions. Moreover, dogs with presumed disseminated HSA had significantly higher SDMA concentrations than those without metastatic disease (median: 21.5 vs. 12 μg/dL; p = 0.012). In contrast, plasma ADMA concentrations did not differ significantly among groups (p = 0.39). These findings suggest that lymphoma and HSA may represent extra-renal causes of SDMA elevation in dogs, and that SDMA could have value as a biomarker of tumour burden or progression. The potential clinical utility of ADMA in canine cancer warrants further investigation.