Imaging features of renal ectopia and fusion in 13 cats.

case series summaryA retrospective multicenter case series of renal fusion anomalies in cats was investigated. The aim of this study was to describe the imaging characteristics (radiography, ultrasonography and CT) of renal ectopia and fusion in cats. A total of 13 feline patients (median age 9 years) were included in this multicentric retrospective study. Ultrasound was available in 12/13 cases, radiographs in 4/13 cases and CT in 3/13 cases. Of the 13 cases, seven were left to right fusions, four were right to left fusions, one was on the midline and one was in the pelvic inlet. Adopting a human classification system, there were five lump kidneys, four disc kidneys, one horseshoe kidney, one caudal ectopia, one L-shaped kidney and one pelvic kidney. In 2/13 cases, additional congenital malformations were noted, including an azygous continuation of the caudal vena cava and a peritoneal-pericardial diaphragmatic hernia. RELEVANCE AND NOVEL INFORMATION: This study provides further description of the imaging findings in feline patients with fused renal ectopia. The morphologic characteristics of the fused kidneys in cats appear similar to what is published in the human literature. Renal fusion might be an incidental finding in cats, but further investigations are necessary to determine their clinical relevance.