Diagnosis and Surgical Treatment of a Renal Cyst Causing Unilateral Lameness in a Golden Eagle (Aquila chrysaetos )

This report describes the diagnosis and treatment of a benign renal cyst in an adult, female golden eagle (Aquila chrysaetos) presented for unilateral leg lameness. A cyst at the cranial division of the left kidney was diagnosed by computed tomography and was suspected of compressing the lumbosacral nerve plexus, resulting in limb lameness. The renal cyst was incompletely excised because the cyst wall was closely adhered to the kidney parenchyma and local blood supply. Fluid analysis and surgical biopsy of the cyst and left kidney confirmed the diagnosis of a benign renal cyst. No evidence of an infectious, inflammatory, or neoplastic etiology was noted. Postoperatively, the eagle's lameness resolved and the bird was ultimately released following recovery. During treatment for the renal cyst, the eagle was concurrently found to have increased serum titers on elementary body agglutination for Chlamydia psittaci and a positive titer for Aspergillus species antibody testing. The bird was administered doxycycline, azithromycin, and voriconazole for treatment of these potential pathogens prior to release. Unfortunately, the eagle was found dead 86 days postrelease due to an unknown cause. To the authors' knowledge, this is the first report of a golden eagle with a benign solitary renal cyst causing unilateral lameness secondary to nerve compression that was resolved with surgical excision.