Renal dysplasia with unilateral renal agenesis in a dog.

This report describes a renal dysplastic lesion associated with renal agenesis in a 3-year-old dog with chronic renal failure. Haematological examination revealed non-regenerative anaemia, azotaemia, increased creatinine and hyperphosphataemia. At necropsy, the right kidney and right ureter could not be identified. The left kidney was slightly enlarged, with a reduced cortico-medullary ratio. Histologically, the medulla of the left kidney had persistent mesenchyme and primitive tubules (tall pseudostratified columnar epithelium), dilated collecting ducts lined by flattened epithelium, and adenomatoid proliferation of cuboidal epithelium; fetal or immature glomeruli could not be identified. To our knowledge, this is the first report of a renal dysplastic lesion with unilateral agenesis in animals.