Cows that experienced cystic ovaries had calving intervals nearly 2 months longer than herdmates without cysts. Because of financial consequences associated with ovarian cysts in dairy cows, scientists have studied the disease for over 100 years. Future research may determine why some follicles develop into cysts, factors or traits that make a cow more likely to develop cystic follicles and methods for treatment of cystic cows to minimize extra days open. The following is a brief summary of current knowledge concerning cystic ovarian disease in dairy cattle. Major categories of cysts include follicular cysts, luteinized follicular cysts and cystic corpora lutea.
Follicular cysts result from failure of ovulation and luteinization.
Follicular cysts are blister-like structures, flaccid to the touch. Cystic CL are CL with a fluid filled center. Several early researchers did not find cystic CL in pregnant cows and reasoned that cystic CL could not support pregnancy. However, researchers at Cornell University report that a CL needs to produce only approximately 100 ug of progesterone to support pregnancy. Therefore, a cystic CL could maintain pregnancy.