A 10-week-old male neutered domestic shorthair cat was presented to Cornell's Emergency Service for a 2-week history of vomiting, decreased appetite, lethargy, and weight loss. An abdominal ultrasound was performed and revealed right sided hydronephrosis and hydroureter. Multiple dilated loops of bowel were noted which were consistent with an obstructive pattern. The following morning, the cat was transferred to Cornell's Soft Tissue Surgery Service for an abdominal exploratory. A right sided ureteronephrectomy and a resection and anastomosis of the jejunum were performed. The tissues were submitted for histopathology examination. The cat recovered well and was discharged two days after the surgical procedure. This report will discuss the case in detail, focusing on causes of hydronephrosis, surgical procedure for removal of the kidney, as well as a brief review of kidney development.