12. therio- cystic ovarian disease in dairy cattle

what is the importance of cystic ovarian disease?

-compromises normal ovarian activity

-results in subfertility and reduced reproductive performance

-additional costs of days open (20-30 days), semen costs, culling, tx expenses

what is a cyst?

single or multiple anovulatory follicles, at or equal to 20mm in the absence of a CL

failure to ovulate at typical ovulatory size (15-17mm) results in continued growth and cyst formation

what are risk factors of ovarian cysts in dairy herds?

-2nd and greater lactation

-early lactation

-high milk yield/genetics

-summer calving

-fat cows/ketosis

-stress

-health problems such as uterine infection or lameness

does high milk yield directly cause cystic ovaries in dairy cattle?

no

which feed ingredients can cause cystic ovaries?

ingredients that contain estrogen-like compounds known as isoflavones or phytoestrogens

-->may be found in legumes like red clover, or in whole soybeans and moldy grain feed

when do follicular cysts most commonly occur? how do they appear?

between 15-45 DIM

are usually large, thin-walled single cysts on one or both ovaries

what is the typical disease course of ovarian cysts?

after developing, spontaneous recovery of cystic follicles occurs in nearly 60% of cows before first postpartum ovulation and may never be diagnosed

which diagnostic method is best for diagnosing cystic ovaries?

ultrasound (higher specificity/sensitivity than rectal palpation)

how do ovarian cysts appear on ultrasound?

fluid filled, anechoic structures greater or equal to 17mm

how is ultrasound used to diagnose cystic ovaries?

-U/S used to evaluate thickness of follicle wall/degree of luteinization

-very useful to distinguish a cyst form a soft CL with no palpable papilla

how can rectal palpation support/aid in diagnosis of cystic ovaries?

-follicle greater than ovulatory size

-lack of uterine tone

-lack of a CL

what are the different types of bovine cystic follicles?

1. follicular cyst

2. luteal cyst

3. cystic CL

what is a follicular cyst? how are they differentiated from luteal cysts?

most common type of cyst

progesterone levels in blood are less than 1ng/mL (low progesterone bc no luteal tissue)

what is a luteal cyst? how are they differentiated from follicular cysts?

less common

progesterone levels in blood are more than 1ng/mL (bc luteal tissue is present to produce progesterone)

what is a cystic CL?

a normal finding in cows, not pathologic

what is the basic problem of ovarian cysts?

failure of positive estradiol feedback to stimulate a surge of GnRH from hypothalamic centers responsible for inducing the pre-ovulatory surge of LH

what can alter release of LH resulting in failure of ovulation?

-pre-ovulatory surge of LH is absent

-insufficient magnitude

-improperly timed

-failure of estradiol to induce LH surge, positive feedback fails

-prolonged estradiol and inhibin secretion

-loss of progesterone negative feedback

what is the end result of ovarian cysts?

follicle growth continues with LH support (variable E2 and P4 concentrations, depends on stage)

may progress to become partially luteinized (=luteal cyst)

what are the treatment goals for ovarian cysts?

cyst regression followed by ovulation and CL formation within 15 days

increase circulating progesterone (via CIDR, etc.)

why would you want to increase circulating progesterone to achieve cyst regression?

exposure to progesterone for 7 days restores hypothalamic responsiveness of estradiol

this is done by inducing ovulation of luteinization of a follicle and CL formation or by exogenous progesterone administration

what are the therapeutic strategies for treating ovarian cysts?

1. give GnRH

-to induce LH surge and ovulation or luteinization of functional follicle. P4 elevated for 15-18 days which resets hypothalamus

2. give hCG (used in refractory cases, but 75% return to cyclicity)

3. give GnRH followed by PGF 7days later

what is the strategy for treating cysts with progesterone (CIDR) for 7 days, followed by PGF at removal?

-CIDR reduces LH and cyst regresses

-normal feedback is now restored

-new wave emerges when CIDR is removed

-pregnancy rate similar to ovsynch

what does use of ovsynch + CIDR result in for treating ovarian cysts?

the highest pregnancy rates (52%)

how can ovarian cysts be prevented?

-reduce incidence of nutritional/metabolic disorders

-genetic selection

-reduce stress (ensure good transition cow management)