Evidence of renal tubular injury in canine patients after elective desexing.

Objective: To investigate the frequency of perioperative acute kidney injury (AKI) in American Society of Anesthesiologists (SA) Grade I canine patients undergoing elective desexing using urine microscopy techniques and assess if pre- and intraoperative factors affect risk of developing AKI.

Design: Prospective observational clinical study conducted between September 2020 and October 2020.

Setting: University teaching hospital.

Animals: Thirty-two female and four male dogs between 5 months and 5 years of age classified as ASA I undergoing elective desexing surgery.

Methods: Urinalysis was performed preoperatively and 20-24 h postoperatively to identify markers of renal tubular injury (RTI), particularly the presence of granular and renal tubular epithelial cell (RTEC) casts on sediment analysis. Dogs underwent a full physical examination and a preoperative assessment including measurement of urine specific gravity (USG), packed cell volume (PCV), total plasma protein and serum creatinine (sCr) was conducted as a part of the desexing programme. Anaesthetic records were examined for any evidence of intraoperative hypotension, defined as a mean arterial pressure (MAP) of <60 mmHg for any duration of time. MAP was measured using an indirect oscillometric technique. For analysis, animals were subdivided into affected and nonaffected groups, with affected animals those that had postoperative increases in granular and RTEC casts. Categorical and comparative analyses were then performed between groups to identify associations of increased casts with pre-, intra- and postoperative variables.

Results: A frequency of RTI of 5.6% was identified. This was accompanied by a significant association between increases in casts with total duration (p = 0.027) and number (p = 0.016) of hypotensive episodes.

Conclusions: RTI is an anaesthetic consideration in ASA I veterinary patients undergoing elective desexing surgery. The identification of an association between the total duration and number of hypotensive episodes and the frequency of RTI highlights the importance of early detection of hypotension along with prompt and effective intervention in veterinary patients.