subject: Cystic ovaries in cows [print this page] Cystic ovaries in cows Cystic ovaries in cows
Cystic ovaries in cows
BY PROF G M WANI,MVSC,PhD,DVM(Germany) .
WHAT IS CYSTIC OVARY
When a follicle fails to ovulate and oocyte remains in the ovary either luteinize and called as lacteal cyst or follicular cyst. In the past we used to diagnose it per rectum at manual examination of genitalia vies rectum. This was called rectal palpation.
The follicular cyst was watery and a thin walled one just like a balloon filled with water, the lutein cyst is thick walled cyst and is hard and difficult to crush manually.
The incidence of cystic ovaries is 10-13 % (Garverick,1999, the cystic ovarian condition in cattle has been reviewed several times in the past.(Amer and Mahdi2011,,Mir and wani,1990) CAUSES Physical factors which predispose cystic ovaries are, high milk yield, hot season, stress and negative energy balance.(Seguin,1998,Lopez-Gatius et al,2002)
Hormonal factors.
The absence of preovulatory GnRH and LH surge.The surge may be due to hypothalamic insensitivity to estradiol surge. The inadequate exposure of the progesterone may be also an associated factor for this total hormonal misbalance.(Gumen and Wiltbank,2002)A relationship between the circulating progesterone in the plasma and cystic ovarian follicles has been reported (Halter et al,2003) Some veterinarians still use manual rupture of the cystic structures(Seguin 1998).
The hormones such as GnRH, hCG, LH and progesterone are frequently used to treat this condition (Thatcher et al 1993).The response of all synchronization,superovulation protocols along with the hormones like hCG,LH,or GnRH are variable.
The varialability of these protocol has been the biggest hurdle in all such experiement.Many attempts of its use during the phase when normal atresia is functional, the protocols of cahill 1980 from France and wani et al,1990 from Germany were pioneer attempts to have a different hormonal use regimes in sheep and Goats,
However ,neither the 1980 protocol nor those of 1990s or 2000 could reduce varialablity. Some recent protocols for synchronization of ovulation, commonly referred as ovsynch, followed by timed artificial insemination (AI) performed 16-20 h after the 2nd GnRH injection yields pregnancy rates of about 25% in cows suffering from COF (Fricke and Wiltbank 1999; Bartolome et al 2000; Meyer et al 2007).
The response to treatment with GnRH, PGF2 and GnRH were not fully documented. Diagnosis of the follicles Diagnosis of a ovarian cystic follicles (Follicular) is based on the palpation per rectum of an abnormally large (20 mm) follicle and no corpus luteum, verified by transrectal ultrasonography (Bartolome et al 2000)
.The luteal cysts are harder and the ovary is with persistent corpus luteum on it .It was found that after the 1st GnRH injection, new existing follicle ovulated, and new follicles developed in cows which ovulated within 48 h of the 2nd GnRH injection, confirmed by the development of a CL. Follicular ovarian cyst.
There are three types of ovarian cysts according to hormonal profiles and ovarian palpable morphology.(Garverick 1999)the classification was based on rectal and ultrasonographic scanning (B-mode System; Pie-Medical Scanner-240 with 6-8 MHz linear rectal probe as performed by Yoshioka et al 1996);
The Cows with at least one large follicular structure (20 mm), no CL, low progesterone (1 ng/ml) and low estradiol concentrations were classified as having persistent cyst.
