Pyelonephritic end-stage kidney and ureterocutaneous fistula in a Shetland pony.

A 12-year-old Shetland Pony was examined for a mucus-secreting fistula (an abnormal passageway) located in one part of its body, leading to the discovery of a severely atrophied and fibrotic kidney, a thickened ureter, and an unusual case of ureterocutaneous fistula.

Overview of the Case

• The research paper revolves around a unique case study of a 12-year-old Shetland pony that was presented with a fistula – an abnormal opening or passage – in the right paralumbar fossa, an area on its body near the lumbar region of the backbone.
• The pony died during surgery that was aimed to investigate the origin of this fistula. Autopsy followed soon after.

Findings from the Autopsy

• At autopsy, significant abnormalities were identified in the pony’s right kidney. Its right kidney was found to be markedly atrophied, a condition where an organ wastes away due to the degeneration of cells. The kidney was also fibrotic, indicative of excessive fibrous connective tissue development as a reparative or reactive process.
• The right ureter, a tube that carries urine from the kidney to the urinary bladder, was also unhealthily thickened but still maintained a luminal continuity leading into the urinary bladder.
• The urinary bladder showed partial obstruction caused by nodular para-ureteral fat necrosis. Nodular para-ureteral refers to the area surrounding the ureter, and fat necrosis is the death of fat cells, creating a blockage.

Diagnosis of the Case

• The lumen of the cutaneous fistula – the interior space of this abnormal passageway – was found to be continuous with the right ureter, forming a pathway from the ureter to an opening in the skin. From these findings, the researchers definitively diagnosed this as a case of ureterocutaneous fistula.
• It’s worth noting that anomalies of the ureter are uncommon, and to the authors knowledge, there has been no previous report of ureterocutaneous fistula formation in equids, like horses or ponies. So, this study presents a first-of-its-kind case in equine veterinary medicine.