Metastatic calcification has been identified on screening thoracic and abdominal radiographs of cats presenting for renal transplantation. In people, metastatic calcification in uremic patients is well described, but a paucity of data exists in the veterinary literature. The objective of this study was to report the incidence of metastatic calcification in cats presenting for renal transplantation, and to determine if an association exists between metastatic calcification detected prior to renal transplantation with complication rates, and patient survival. Imaging studies of 178 feline renal transplant recipients from 1998-2020 were evaluated for evidence of metastatic calcification. Demographic, clinicopathological data, intraoperative complications, postoperative complications, and survival times were recorded. Seventy-four of 178 cases that underwent renal transplantation were included. Fifteen of 74 (20.3%) cats had metastatic calcification identified prior to transplantation, 12/74 (16.2%) cats developed calcification following transplantation, and 47/74 (63.5%) cats had no calcification identified. Cats with pre-transplant calcification had significantly shorter median survival times (147 days) than cats without calcification (646 days) (p = 0.0013).Metastatic calcification pre-transplant significantly increased the risk of death by 240% (95% CI, 122-471%). Vascular calcification has been directly associated with increased risk of cardiovascular disease and mortality in people undergoing hemodialysis. Our findings suggest a similar negative prognostic effect in feline patients undergoing transplantation. Limitations to this study are its retrospective design, small sample size, and lack of standardized follow-up that may underestimate development of post-transplant calcification and complications. These findings may help guide therapeutic recommendations and client expectations in cats undergoing renal transplantation.
