A tubo-ovarian cyst, paraovarian cysts and lesions of the oviduct in the mare

A tubo-ovarian cyst caused unilateral obstruction of ovum transport in a young Thoroughbred mare. Its effect was a reduction in reproductive efficiency since ovulations from the affected ovary were unproductive. No occluded oviducts were found among 24 pairs of oviducts examined at post mortem. Occlusion of the oviducts in mares is apparently extremely rare. The most common types of cysts found in association with the ovaries in mares are small paraovarian cysts. They are usually found in the fimbriated portion of the oviduct and do not interfere with fertility.