Ovarian cysts in dairy cows: old and new concepts for definition, diagnosis and therapy
Anim Reprod, vol.11, n2, p.63-73, 2014
Ovarian Cyst (OC) is an important ovarian dysfunction and a major cause of reproductive failure in dairy cattle. Previously defined as enlarged anovulatory follicle like structures (<2.5 cm) and persisting for 10 or more days OC in dairy cows are currently defined as cystic ovarian follicular structures of at least 17 mm that persist for more than 6 days in the absence of corpus luteum. However, clear cut definitions of this disorder are yet to be made. Past evaluations of OC using transrectal palpations have increased, and accurate diagnosis currently employs a combination of transrectal palpation, transrectal ultrasonography and plasma progesterone assay. However, the accurate diagnosis of the type of OC seems less important as therapies are similar for both the types of OC and clinicians often evaluate the OC again under conditions of pregnancy failures. During earlier times, the manual rupture of OC was advocated, yet during the past several years single or combination hCG, GnRH, progesterone and prostaglandins have been frequent in clinical practice. Other therapies include estrogen receptor blocker clomiphene citrate and trans-vaginal ultrasound guided cystic follicle aspiration. Among the various therapies suggested the OvSynch treatment appears to be the most logical approach, yet the pregnancy rates with timed inseminations following therapy with the OvSynch treatment are low, as with other hormonal treatments. The success of therapy is governed by many confounding variables such as persistence of the cystic follicles and initiation of therapy as pathological alterations that occur following OC persistence require some time for spontaneous recovery. It can be concluded that OC can be diagnosed easily yet in spite of many therapeutic options the establishment of pregnancy in cows with OC requires a longer time.
cows, CL, follicles, GnRH, ovarian cyst, ovsynch, ultrasonography