Seminomas are a common neoplasm in domestic dogs,2 that arise from testicular germ cells in both cryptorchid and scrotal testicles3. Although surgical castration is considered curative in most cases, seminomas have the potential to metastasize.3 A seminoma has been reported as an incidental finding in an American black bear (Ursus americanus), but is not well described.1 This case series documents two cases of testicular seminoma in aged giant pandas (Ailuropoda melanoleuca) in North American zoological institutions. The first case involves a 26-year-old male giant panda, who presented with an enlarged, firm right testicle during routine examination. A fine needle aspirate of the testicle indicated a neoplastic process and a bilateral castration with subsequent histopathology revealed a seminoma of the right testicle. Surgical castration was believed to be curative, as no metastasis or evidence of recurrent seminoma was observed at necropsy 2.5 years later. The second case involves an approximately 24-year-old male giant panda, who presented with a mildly enlarged, firm right testicle during a routine exam. Ultrasound revealed a hypoechoic nodule within the right testicular parenchyma, but a fine needle aspirate of the nodule was non-diagnostic. One year later, the testicle was markedly enlarged with a heterogeneous and hypoechoic mass relative to the remaining normal testicular parenchyma on ultrasound. A core biopsy was taken and indicated a seminoma. A hemicastration was performed and histopathology confirmed a seminoma, which replaced 90% of the testis. No signs of metastasis were noted at time of diagnosis.
1. Brito L, Sertich P, Rives W, Knobbe M, Del Piero F, Stull G. Effects of intratesticular zinc gluconate treatment on testicular dimensions, echodensity, histology, sperm production, and testosterone secretion in American black bears (Ursus americanus). Theriogenology. 2011;75:1444–1452.
2. Hayes H, Pendergrass T. Canine testicular tumours: epidemiologic features of 410 dogs. Int J Cancer. 1976;18(4):482–487.
3. Hedlund H. Surgery of the male reproductive tract. In: Fossum T, ed. Small Animal Surgery. St. Louis, MO: Mosby, Inc.; 2007:759–762.