Bilateral testicular seminoma in a captive Siberian chipmunk (Tamias sibiricus).

A 5-year-old male Siberian chipmunk (Tamias sibiricus) was presented with marked enlargement of the left testicle. Differential diagnoses included testicular neoplasia such as seminoma, interstitial cell neoplasia, Sertolli cell neoplasia and teratoma or orchitis. Fine needle aspiration of the left testicle was performed under general anesthesia and cytologic findings were consistent with seminoma. Following bilateral orchiectomy, both testicles were examined histologically, revealing bilateral diffuse seminoma. The chipmunk made an uneventful recovery from anesthesia and was treated with analgesics. Follow up two years after surgery, no clinical signs were observed. Seminomas are rare in chipmunks, but orchiectomy may result in long-term disease-free survival as described in other myomorph rodents.