Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

DVM3: Horses - Reproduction > Equine pregnancy > Flashcards

Equine pregnancy Flashcards

1
Q

Where is semen deposited by the stallion?

A

Uterus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where does fertilisation of the ovum occur?

A

Ampulla of the oviduct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When does the conceptus enter the uterus (days post-OV)

A

d5-6 post-OV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens to unfertilised ova?

A

Retained in the oviduct as don’t secrete PGE2 (which relaxes ampullary-isthmic jcn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Timeline of conceptus from fertilisation to implantation

A

Fertilisation = 12hr post-OV

Entry to uterus = d5-6 post-OV

Mobile conceptus in uterus = d6-d15 (mat recognition of pregnancy)

Fixation = d16 post-OV (at base of uterine horn)

Implantation = d35

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Mechanism of maternal recognition of pregnancy in mares

A

Conceptus is mobile in uterus (d6-15) > contacts every cm of uterus multiple times/day > prevents endometrial release of PGF2a (luteolysin) > maintains CL/high P4 for pregnancy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When/where does fixation of the conceptus occur? Why?

A

d16/17 at base of uterine horn (jcn w uterine body)

  • grows too big to migrate so gets stuck
  • implants in either horn (irrespective of side of OV)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the nutritional source for the conceptus before & after implantation (d35)?

A

Before = histiotroph (uterine milk) + yolk sac

After = diffusion of nutrients across placenta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Until what day is loss of the embryo considered EEL? When does it most commonly occur?

A

EEL = loss before d35 (implantation)

  • most often before d11 (before pregnancy dx)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are some causes (+ eg’s) of EEL in mares?

A

Intrinsic mare factors = endometritis, endometriosis, P4 deficiency, poor nutrition

Extrinsic mare factors = heat, stress, transport

Embryonic factors = chromosomal abnormalities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the role of eCG in equine pregnancy? From what structure is it derived?

A

eCG = luteotrophic > causes formation of accessory CLs on ovaries > maintains high P4 from d40-120 of pregnancy TF maintains early pregnancy

Source = endometrial cups (discrete raised areas of the placenta which invade the maternal endometrium)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the 3 sources of P4 in mares during pregnancy & when are they functional?

A

Primary CL (≤d180)

Accessory CLs (d40-120)

Placental 5-a-pregnanes (≥d100)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When is the first US pregnancy Dx?

A

d14 –> follicle-like spherical structure in uterus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When are the routine US pregnancy exams in mares + what do each check?

A

d14 (post-OV) = conception

d25-28 = viability (hearbeat)

d40 = endometrial cups/amnion formed > stud fee due

d60-70 = foetal sexing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What presumptive signs of pregnancy may be considered?

A

Served by a stallion

Oestrous periods have stopped (test w teasing)

Change of temperament

Abdo enlargement (>5mo)

Foetal movements

Udder enlargement (last month)

Relaxation of sacro-sciatic lig’s (last 2-3wks)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why do twins occur (usually)?

Where does fixation of twin conceptuses usually occur?

A

Double OV (>90%)

  • 50% = unilateral double OV (hard to spot on US)
  • 50% = bilateral double OV (always check both ovaries)

>70% unilateral implantation

17
Q

What must be considered in checking for twins at the d14 pregnancy dx exam?

A

Asynchronous OV (1-4 days)

  • size difference ≤ 4mm of conceptuses
  • TF smaller conceptus is easily missed (as could be as young as d10 TF undetectable)
18
Q

What is the cause of abortion in equine twin pregnancies?

A

Lack of placental area to support both foetuses

  • smaller foetus (w less placental area) dies
  • drop in 5-a-pregnane causes abortion of both

If born alive, both twins will be weak/runty

19
Q

Signs of a double OV

A

Mare displaying signs of oestrus (winking etc.) after 1st OV

20
Q

If a double OV is confirmed, when should preg dx exam be?

A

d14 post-OV

  • look for 2 concepta
  • if concepta are separated > crush one
21
Q

What actions should be taken in the event of double concepta being visible at the d14 exam (before fixation)?

A

Crush one of the concepta

  • only if concepta are sufficiently separate (may damage both if together)
  • once start crushing one, finish the job!
  • re-examine at d33-34 (before endometrial cups form) - spontaneous reduction may have occurred
22
Q

What is spontaneous twin reduction?

When does it occur?

What factor is most important in determining whether it will occur?

A

Natural loss of one of the twins

B/w d17-40 of gestation

Dependent on location of fixation

  • Unilateral fix = >80% spontaneous reduction
  • Bilateral fix = very low % spont. red
23
Q

What management options are available in the event of unilateral twins after fixation?

A

Manual crush one before d35 (low success rate)

PGF2a (luteolysis) > kill both embryos + start again

Transvaginal US-guided needle aspiration (50% success of one reaching term)

24
Q

What measures can be taken to ensure twins aren’t missed?

A

Always scan both ovaries for a dominant follicle

Look for 2 dom follicles on the same ovary

If single OV recorded but 2 CL seen at preg exam (d14), recheck for a 2nd conceptus 2 days later (d16 = d12-14 of 2nd conceptus)

25
Q

What actions should be taken in the event of bilateral twins dx’d after fixation (d16)?

A

Crush immediately

  • spontaneous reduction is very very very unlikely
  • may still lose both concepta
  • keep teasing mare to monitor for return to oestrus
26
Q

What is the latest day of pregancy which action to reduce twins can be taken + why?

What actions can be taken if twins not reduced by this stage?

A

d40 of pregnancy = endometrial cups formed > termination ≠ return to oestrus (as high P4 remains until d120)
TF season is lost!

Owner’s decision:

  • high risk of dystocia/premature/non-viable/non-athletic foals if carried onward
  • wait-and-see approach > act before d80
27
Q

DDx for premature udder development

A

Twin pregnancy in which 1 twin has died (tx = give high dose progestagens to allow carriage of other to term)

Placentitis

28
Q

What causes spontaneous abortion of both twins in a twin pregancy?

A

1 large embryo = occupies uterine body + 1 horn

1 small embryo = occupies 1 horn only

  • low placental contact area = hypoxaemia > death
  • death = stress signal > induces premature parturition of large foetus
  • death = sudden drop in 5-a-pregnanes > can’t maintain pregnancy
29
Q

Clin signs of placentitis

A

Premature udder development

Vaginal discharge

± pyrexiia

30
Q

Route of infection in placentitis

Eg’s of agents

A

Ascending infection

  • Strep equi zooepidemicus*
  • E. coli*
  • Klebsiella pneumoniae*
31
Q

Dx methods of placentitis

A

Transrectal US

  • measure combined thickness of uterus and placenta (CTUP)
32
Q

Tx + mgt of placentitis

A

AB - penicillin/gentamycin/TMS

Exogenous P4 to maintain pregnancy

Flunixin meglumine

Pentoxifylline

Check foetal viability weekly (if not more)

DVM3: Horses - Reproduction (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions