Evaluation of symmetric dimethylarginine (SDMA) in canine acute pancreatitis

Symmetric dimethylarginine (SDMA) is a sensitive renal biomarker whose concentrations increase earlier than creatinine as glomerular filtration rate decreases. So far in humans, SDMA is considered an important early biomarker of kidney dysfunction. The aim of this study was to evaluate SDMA in dogs with acute pancrea- titis (AP) and their association with kidney injury and severity of disease. Dogs with AP, presented at the Veterinary Teaching Hospital of Uni- versity of Pisa between 2017 and 2019, were prospectively enrolled. AP diagnosis was based on compatible clinical and laboratory parame- ters, abnormal SNAP cPL test (Idexx Laboratories) and positive abdominal ultrasound within 48 h from admission. Dogs with a history of renal diseases (clinical records/history, bloodwork and diagnostic imaging), urinary tract infection and/or on hemodialysis treatment were excluded, along with dogs that had received known nephrotoxic drugs (eg. non-steroidal anti-inflammatory drugs, aminoglycosides). For each dog, data about urea, creatinine and urinary output (UO) were recorded. Acute kidney injury (AKI) grading was made based on current IRIS consensus. Canine Acute Pancreatitis Severity (CAPS) was calculated for each dog at presentation and previously described cut-off of 11 was used to divide dog into two groups (CAPS < and > 11). SDMA was measured using high performance liquid chro- matography (HPLC). The SDMA was compared between UO groups (O, NO), presence of AKI and with CAPS score groups using Mann- Whitney U-test or Welch's t-test based on normality distribution. SDMA was correlated with urea and creatinine levels using Spear- man's correlation test. Fifty-one dogs with diagnosis of AP were enrolled with owners' informed consent. Sixteen dogs showed AKI and 11 of them were oligo-anuric. Overall median SDMA was 13.8mg/dL (range 0.6-65 mg/dL). Twenty-three dogs (45%), of which 13 in non-AKI group, had SDMA above reference range (15 mg/dL). Median SDMA was significantly higher in AKI dogs (18.5 vs. 12.4 mg/dL; P = 0.01). Both urea and creatinine concentration showed a positive correlation with SDMA level in AKI dogs (P = 0.01 r = 0.6 and P = 0.006 r = 0.7, respectively) but the same correlations were not significant in non-AKI group. No association between SDMA and UO was found. Finally, dogs with CAPS>11 had higher SDMA compared to dogs with CAPS<11 (26.9 5 mg/dL vs. 13.8 1.5 mg/dL, P = 0.03). Based on our results, SDMA seems to be associated with disease severity (CAPS). SDMA correlates well with kidney disfunction parameters (urea and creatinine) and results higher in AKI dogs. Interestingly, about 1/3 of non-AKI dogs presents abnormal SDMA that can be related to a sub- clinical kidney impairment.