Disturbances in ovarian function Flashcards
Hormonal steps to successful ovulation.
Preovulatory LH surge results in increased blood flow to the ovaries and dominant follicle, edema.
PGF2-alfa increases and causes ovarian smooth muscle to contract which increases the pressure inside the follicle.
Estradiol production in side the dominant follicle changes to progesterone.
Collagenase enzyme levels rise.
Lysosomal enzymes are released.
The follicle wall weakens.
Finally, ovulation due to all of the above.
Name 5 structures that can be found within the ovaries (not necessarily at the same time.
follicles
corpus luteum or cystic corpus luteum
luteinized follicles
luteinized cysts
follicular cysts
Describe regular ovarian follicles. (3)
Up to 1.5 cm in diameter
Present in all cycle stages
In crease in size to 1.5 – 2.0 cm during estrus and 12 h postestrus.
Describe Corpus luteum or cystic corpus luteum. (5)
Outcome of ovulation.
Protrude from the surface of the ovary, are thick structures.
Involved in regulation of the estrous cycle.
Not associated with infertility.
A cystic corpus luteum contains a fluid-filled cavity in its center. It is a normal physiological variation of the corpus luteum in cattle and does not typically affect fertility or estrous cycles. Cavity inside will be filled when cow is pregnant.
Describe luteinized follicles. (4)
Luteinized follicles in cattle refer to follicles that undergo luteinization (the process where follicular cells transform into luteal cells and produce progesterone) without actually ovulating.
This condition occurs when a dominant follicle fails to rupture and release an oocyte but instead forms a structure similar to a corpus luteum but They have no protruding area like corpus luteum have.
Luteinized follicles develop in regularly cycling cattle due to disruptions in the ovulatory process, often related to hormonal imbalances. Some key reasons include:
insufficient LH surge
prostaglandin imbalance
failure of follicle wall to break down
etc.
In most cases, treatment with prostaglandin F2α (PGF2α) helps regress these structures and restore normal cycling.
Describe luteinized cysts.
Luteinized cysts are ovarian cysts that form when a follicle fails to ovulate but undergoes luteinization, leading to a thick-walled, progesterone-producing structure.
Unlike a normal corpus luteum, luteinized cysts do not result from ovulation and can cause prolonged anestrus (absence of estrus).
Treatment – Responds to PGF2α, which induces luteolysis and restores normal cycling.
How is a luteinized follicle different from a Luteinized Cyst?
A luteinized follicle and a luteinized cyst share similarities in that both involve follicular structures undergoing luteinization without ovulation. However, they differ in their formation, structure, and effects on the estrous cycle.
Luteinized follicles don’t typically interfere with estrus but luteinized cysts DO. They cause anestrus.
Tx of luteinized follicles: May resolve naturally or respond to GnRH/PGF2α protocols.
Tx of luteinized cysts: Requires prostaglandin F2α (PGF2α) to induce luteolysis and restore cycling.
Describe follicular cysts.
Follicular cysts are ovarian structures that form when a dominant follicle fails to ovulate and persists beyond the normal estrous cycle.
They are thin-walled, fluid-filled, and often lead to reproductive dysfunction in cattle.
Often there are several present, they are big and in both ovaries.
3 paths that follow non-ovulation/ unsuccessful ovulation:
follicular regression and atresia
follicular luteinization and later regression
continuous follicular growth and cyst formation
Describe Delayed ovulation. (4)
Hard to diagnose because its necessary to perform repeated rectal investigations.
Diagnosis is confirmed when you find the same follicle in the same ovary in the same place during estrus and 24 – 36 h after estrus.
Treat with hormones (GnRH), which lead to ovulation.
Alternative method is 2 inseminations one during estrus and second 24 h later.
Review this table.
Describe “non-ovulation”. (6)
Non-ovulation in cattle refers to the failure of a cow or heifer to release an egg during the estrous cycle.
May be associated with anestrus. Before the animal “falls into anestrus”, there might be estrus without ovulation.
Frequently occurs during the first 2 post-partum weeks (during rectal palpation we may find big non ovulated follicles).
Diagnosis is difficult (retrospective). Only thing that we will find is the follicle which is still there/persists.
If this follicle luteinizes, it will stay for 17 – 18 days (round, smooth ovarian surface and we can feel some fluctuation (different from corpus luteum)).
Treatment needs to induce ovulation (hCG or GnRH).
True anestrus refers to
inactive ovaries.
The ovaries can also remain inactive due to suckling. This is mainly dependent on: (4)
body condition of the dam
presence of the calf (not only suckling)
season of the year
age of the cow
Body condition in beef cows at calving.
And at weaning?
Avoid lean cows at calving.
Body condition in beef cows 1-9:
- 1= lean
- 9= fat
Ideal condition at calving: 7
At weaning: 5
Flushing has a positive effect if:
- condition at calving 5 - 7
- no serious decrease from calving to weaning
- 50 - 80 d pp, give concentrates surplus (weaning at approx. 70 days)
Tx of inactive ovaries.
First treat the underlying cause e.g. lameness, fatty liver, acidosis, ketosis, …
GnRH, FSH or LH treatment will not work efficiently
Treatment of choice is progesterone for 7- 10 days (+ FSH ≤ 400 IU treatment at the moment of progesterone removal) to stimulate estrus and follicular growth.
Cystic Ovarian Disease in cattle (3)
Large, >2,5 cm, follicle-like structure on the ovary (that persists for at least 10 days, in the absence of a corpus luteum, clinical cyclicity problems).
Is an economically important reproductive problem:
mainly causing prolongation of the calving interval.
Incidence of ovarian cysts is increased with increasing milk production.
Pathogenesis of Cystic Ovarian Disease
Is not completely elucidated. Cystic ovarian dz is caused by a failure to ovulate but probably not because of a shortage of LH.
Risk factors:
obesity, nutritional imbalance and metabolic stress factors are stated to be among the most important risk factors for COD + genetics
What’s the effect of NEFAs on granulosa cell proliferation?
Non-Esterified Fatty Acids (NEFAs) negatively impact granulosa cell proliferation in cattle, particularly during periods of negative energy balance (NEB), such as early lactation.
High NEFA concentrations, resulting from excessive fat mobilization, can impair ovarian function and follicular development. may cause reduced production of oestrogens and may hence delay the correctly timed LH surge.
Lower conception rates and increased early embryonic loss.
Prolonged postpartum anestrus in high-producing dairy cows.
Management Strategies: Avoid excessive BCS loss in early lactation. Reduce NEB by feeding high-energy diets.
Especially palmitic and stearic acid (=saturated) reduce cell number, already at a concentration of 150 µM. Oleic acid (=mono-unsaturated) only effect at an elevated concentration.
Follicular cysts on palpation, are…
thin walled, often several in both ovaries, uterus is atonic.
Progesterone: < 0,5
(Luteinized cysts are thick-walled and usually only in one ovary.)
Symptoms of follicular cysts: (3)
Persistent estrus symptoms that may disappear and come back.
Vaginal discharge (grey color)
swollen vulva
Luteinized cysts on palpation:
More thick walled, less fluctuation, big ovary and often they present only in one ovary.
Progesterone: Low (0- 5)
(Follicular cysts are thin-walled and in both ovaries.)
Symptoms of Luteinized cysts: (3)
Vaginal discharge
No symptoms even
Just anestrus
Development of follicular cysts is
dynamic (with waves)
in intervals of 7– 25 days and disappear when they reach a diameter of 25 mm.
