Problems in Post-Partum Cattle 2 Flashcards
1
Q
- Define cystic ovarian disease.
- Further classifications of cysts.
A
- A cystic follicle is defined as an anovulatory follicle-like structure (>2cm diameter) that may persist on the ovary (usually for >10 days) w/ or w/o presence of CL.
- Follicular cyst: thin-walled, non progesterone-producing (plasma progesterone <1mg/ml).
- Luteinised / luteal cyst: thicker-walled, progesterone-producing (plasma progesterone >1mg/ml).
- Non hormone producing cyst.
*dynamic structures which may change categories over time.
*many normal CLs have fluid-filled centres (lacunae) visible on ultrasound scan – NOT cysts.
- Follicular cyst: thin-walled, non progesterone-producing (plasma progesterone <1mg/ml).
2
Q
- Incidence of cystic ovarian disease.
- Consequences of cystic ovarian disease.
A
- Varies between 5-30%.
Most develop 20-60 days post partum. - Financial loss due to extended calving-conception period.
BUT, some cysts diagnosed before 40 days post partum self cure (up to 60%).
3
Q
Why may the LH surge fail in a cow with cystic ovarian disease?
A
Stress – cortisol can block or delay normal LH surge or may alter LH receptor activity at follicular level.
– Stress caused by:
–> movement/transport.
–> change in diet.
–> turn-out in Spring.
–> housing in Autumn.
–> high yield.
–> rapid live weight loss.
Metritis / endometritis.
- Endotoxin production from uterus can cause cortisol release which interferes w/ ovulation.
Other possible predisposing factors.
- other dietary deficiencies.
- plant-based oestrogens in diet (probably no in UK).
4
Q
Cystic ovarian disease predisposing factors.
A
- Interaction between hereditary predisposition, stress, milk yield, age, season of the year, and plane of nutrition (poorly understood and some work refutes some of this statement).
- Ketosis, dystocia, twin births, RFM and MF are also considered risk factors.
5
Q
- Cystic ovarian disease clinical signs.
- Cystic ovarian disease diagnosis.
A
- Follicular cysts – irregular or recurrent oestrus behaviour or anoestrus.
- Luteinised cysts – anoestrus.
- Follicular cysts – irregular or recurrent oestrus behaviour or anoestrus.
- Rectal palpation (superseded by ultrasound). – if thick walled structure, likely to be luteinised cyst.
- Milk/blood progesterone analysis.
– Follicular –> low milk progesterone.
– Luteinised –> high milk progesterone.
- Ultrasound.
- Behaviour.
- Rectal palpation (superseded by ultrasound). – if thick walled structure, likely to be luteinised cyst.
6
Q
1, Cystic ovarian disease treatment.
2. Which cysts are quicker to treat?
A
- GnRH or HCG – PGF2a may be given 10-14 days after GnRH.
– Should bring about LH/FSH release.
– Does not bring about ovulation w/ cysts.
–> turns a follicular structure into a luteal structure (luteotropic).
- PGF2a IM if luteal cyst.
- Progesterone.
– PRID/CIDR inserted in vagina for 12 days then removed.
– Oestrus normally occurs w/in 2-3 days of PRID/CIDR removal along w. ovulation of a new dominant follicle.
– Cows can be inseminated at this induced oestrus.
Ovsynch / synchronisation protocols.
- GnRH or HCG – PGF2a may be given 10-14 days after GnRH.
- Luteal cysts.
7
Q
What normally happens regarding the return to normal cyclicity?
A
- During pregnancy and for short period after parturition, cows are acyclic.
- 90% of dairy cows resume cyclicity by 50mdays post partum.
- 70% beef cows cyclic by 50 days post partum.
- 5% may go anoestrus having resumed normal cyclicity.
- Waves of follicles develop and become atretic throughout pregnancy.
- FSH-induced waves of follicular growth soon accompanied by ovulation and return of regular cyclicity following parturition.
- Dairy – 1st pp ovulation w/in 20-30 days.
- Beef – 1st pp ovulation w/in 20-60 days.
8
Q
What normally controls time of first post partum ovulation?
A
- HT/APG.
- By 10-20 days, FSH present in sufficient amounts to stimulate waves of follicular growth.
- BUT ovulation of dominant follicle requires sufficient LH pulse frequency.
- If dominant follicle fails to ovulate it will become atretic or occasionally become cystic.
- Delay in pp ovulation in beef cows compared to dairy cows due to delay in sufficient LH pulse frequency rather than being FSH problem. It is down to the suckling effect.
9
Q
- False anoestrus.
- True anoestrus.
A
- No detectable oestrus.
- No visible oestrus.
- Oestrus not observed.
- No detectable oestrus.
- Any factors causing interference w/ GnRH/LH output in early pp can influence pp anoestrus period.
10
Q
True anoestrus causes – NUTRITIONAL.
A
- Inadequate energy intake in late pregnancy/early pp – extended anoestrus due to suppression of LH pulse frequency.
- Negative energy balance affects levels of insulin and GH which inadvertently affect early follicular growth and oocyte quality.
- NOT CALVED IN OPTIMAL BCS.
- EARLY LACTATION LIVE WEIGHT TOO HIGH.
11
Q
True anoestrus causes – SECONDARY COPPER DEFICIENCY.
A
May cause anoestrus due to excess molybdenum or sulphur in the diet.
12
Q
- True anoestrus causes – suckling effects.
- True anoestrus causes – delayed uterine involution.
A
- Frequency and duration of suckling affects LH output via opioid release interfering w/ GnRH output in HT.
- Assisted calvings.
- RFM.
- Metritis.
- Assisted calvings.
13
Q
Other factors that cause true anoestrus.
A
- cysts.
- Persistent CL. – caused by uterine infection/pyometra.
- Other risk factors:
– high yielding dairy cow.
– 1st calvers which are still growing.
14
Q
Diagnosis of anoestrus.
A
- Most cows presented for exam (>60 days pp) will be cycling normally and have not been observed in oestrus due to poor heat detection.
- To diagnose true anoestrus, need either to:
– Palpate / scan 2 small hard ovaries w/ no CL or large follicles, w/ smaller rectal finding in 10-14 days.
– Have 2 low milk progesterone values recorded 10 days apart.
15
Q
Treatment of nutritional anoestrus.
A
- Sort out management, nutrition, lameness etc.
- Progesterone releasing devices e.g. PRID, CIDR.
– insert in vagina for 12 days –> get LH surge on withdrawal.
– if deep anoestrus may need 400-600 i.u. PMSG injection (particularly suckler cows) at progesterone withdrawal. - GnRH injection – single dose GnRH given >55 days pp will give oestrus in most acyclic cows within 23 days.
