Seminoma is a one-sided, mostly benign (not recurrent or progressive) tumor of testis. In rare cases, malignant forms of tumor have been reported.
Seminoma is the second most common type of tumor and it mostly affects dogs above 4 years of age. It typically measures less than two centimeters in diameter and often causes no symptoms in the affected, making the diagnosis difficult.
Dogs affected with seminoma are mostly asymptomatic but a few may experience pain due to pressure from growing tumor.