Cystic ovarian disease (COD) in cows is usually seen in the first two months post calving. Major categories of cysts include follicular cysts, luteinized follicular cysts and cystic corpora lutea.
Abnormal estrous behavior patterns are the most noticeable sign of cystic ovarian disease. This includes persistent oestrus, shortened oestrus intervals or failure to cycle (anoestrus). Anoestrus is by far the most common sign.
Behavioral aberrations range from frequent, intermittent estrus with exaggerated monosexual drive to bull-like behavior, including mounting. This persistent bulling behaviour, or nymphomania, is by far the least common clinical sign associated with cystic ovaries.
Typically, 5 – 10% of cows are affected with COD per year Hooijer et al., 2001), but the incidence may be up to 30% in older animals.