Crossed renal ectopia with fusion in a cat

In humans, crossed renal ectopia is a rare, usually asymptomatic, congenita l malpositioning of the kidneys, involving wandering of one or both embryon ic kidneys across the midline and usually fusion with its contralateral par tner, This is the first report of crossed renal ectopia in the cat. A 7-yea r-old, neutered male cat was presented with polyuria, polydipsia, and a pal pable abdominal mass. Diagnostic investigations, including clinical patholo gy, survey and contrast radiography, and ultrasonography, confirmed the pre sence of an ectopic left kidney fused with an orthotopic right kidney, with concurrent renal failure and hypertension. Many features of crossed renal ectopia in this cat are similar to those described in humans, however the v ascular supply, the presence of renal failure, and the axial rotation of th e fused kidney are atypical.