Colic signs caused by an unilateral abdominal seminoma in a Friesian stallion

Summary This case report describes the diagnosis and surgical treatment of a 12‐year‐old Friesian stallion that presented with colic and was diagnosed with an unilateral abdominal seminoma. The diagnostic work‐up included haematology, blood chemistry, rectal examination and ultrasonography before the tentative diagnosis of a neoplastic intra‐abdominal testicle was made. The mass was removed surgically and diagnosed as a seminoma via histopathology. Regular follow‐up was performed since suspected metastasis was seen on transrectal ultrasonography and laparoscopy. Unfortunately, the patient was subjected to euthanasia 18 months post‐surgery due to clinical deterioration. Post‐mortem examination was performed and confirmed the cause of clinical deterioration was due to metastasis of the previously removed seminoma. Colic is, to the author's knowledge, rarely seen in stallions with an abdominal testicular neoplasm, in contrast to humans and dogs.