Bilateral renal agenesis in two litters of Shetland sheepdogs.

Two cases of bilateral renal agenesis (1 pup from each of 2 related bitches) were observed in a purebred Shetland sheepdog breeding colony. Gross postmortem and histopathologic examinations confirmed a diagnosis of bilateral renal agenesis as the cause of death. Limited available data strongly suggests an inherited etiology for bilateral renal agenesis. (Editor's Note: This report is published as an example of a situation where circumstantial evidence suggested a cause-and-effect relationship between the change in heartworm medication and the anomalies. Careful scientific data collection and review avoided falling into that trap and identified the genetic basis for the observed defects.