Equine reproduction

Question 1

what is a mare?

Answer 1

female horse over 4 years old

Question 2

what type of breeder is the mare?

Answer 2

long day, seasonal, polyoestrus

Question 3

how long is the oestrus cycle of the mare?

Answer 3

21 days

Question 4

how long is diestrus in the mare?

Answer 4

16-17 days

Question 5

how long does oestrus last in the mare?

Answer 5

4-6 days

Question 6

what does the dominant follicle do once recruited?

Answer 6

produce oestrogen

Question 7

what does oestrogen produced by the dominant follicle do?

Answer 7

induce oestrus

Question 8

what size does the dominant follicle have to be for ovulation to occur?

Answer 8

> 35mm

Question 9

how long does oestrus continue after ovulation?

Answer 9

24 hours

Question 10

what does the ovulation site become after ovulation?

Answer 10

(corpus haemorrhagicum) then corpus luteum

Question 11

what does the corpus luteum produce?

Answer 11

progesterone

Question 12

what causes luteolysis?

Answer 12

prostaglandin

Question 13

what is the transitional period in relation to the mare?

Answer 13

period of change from anoestrus to normal cycling

Question 14

what will be seen on the ovaries if a mare is scanned in the transitional period?

Answer 14

bunch of grapes (follicles that eventually regress)

Question 15

are mares fertile in the transitional period?

Answer 15

no

Question 16

what three hormones can be used to manipulate oestrus?

Answer 16

prostaglandins
progesterons
oestrogens
chorionic gonadotrophin
deslorelin

Question 17

how can prostaglandins be used to manipulate the oestrus cycle?

Answer 17

induce luteolysis of a CL commencing oestrus 3-5 days later

Question 18

how can progestogens be used to manipulate the oestrus cycle?

Answer 18

suppresses oestrus then removal leads to rebound ovarian activity (shorten oestrus)

Question 19

what are oestrogens used for?

Answer 19

induce signs behavioural signs of oestrus (teaser mares)

Question 20

what is chorionic gonadotrophin used for?

Answer 20

induce dominant follicle to ovulate

Question 21

what is deslorelin used for?

Answer 21

induce ovulation in 48 hours with a follicle >30mm

Question 22

how can light be used to manipulate oestrus?

Answer 22

16 hours of light and 8 hours of dark from 2-4 weeks before winter solstice

Question 23

what can be used to suppress oestrus?

Answer 23

longterm progestogens 
intra-uterine device (not encouraged)
anti GnRH vaccine 
long term CL (oxytocin injection)
plant oil in uterus
put in foal
ovariectomy

Question 24

when should mares be served in relation to ovulation?

Answer 24

24-48 hours before

Question 25

what are the 4 signs a mare is in oestrus?

Answer 25

dominant follicle on one ovary uterine oedema soft oedematous cervix behavioural signs

Question 26

if a mare is in oestrus when scanned, when should you next scan her?

Answer 26

24-48 hours later

Question 27

if a mare isn't in oestrus when scanned, what should be done?

Answer 27

prostaglandin and scan in 3-5 days

Question 28

how does the dominant follicle appear just before ovulation?

Answer 28

softer and pointing

Question 29

how does oedema of the uterus appear appear 24 hours prior to ovulation?

Answer 29

starts to decrease

Question 30

how long after mating should a mare be scanned?

Answer 30

12-24 hours

Question 31

what should be looked for on a post mating scan?

Answer 31

has ovulation occurred (only one) | check for fluid in uterine lumen (endometritis)

Question 32

what three mechanisms of perineal conformation are important for prevention of bacterial entry?

Answer 32

vulval seal vestibular seal cervical competence

Question 33

what can failure of the vulval and vestibular seal lead to?

Answer 33

pneumovagina leading to urovagina causing cervicitis and endometritis

Question 34

what is the most common procedure used in mares with poor perineal conformation?

Answer 34

casslicks vulvoplasty

Question 35

what is casslicks vulvoplasty?

Answer 35

suture the vulva lips together (as much as necessary)

Question 36

what effect does a persistent CL have?

Answer 36

no oestrus

Question 37

what are anovulatory follicles?

Answer 37

very large follicles that don't ovulate causing prolonged oestrus (prolonged luteal phase if they ovulate)

Question 38

what are the three types of endometritis?

Answer 38

chronic infectious metritis free fluid in lumen mating induced endometritis

Question 39

how long does the fertilised conceptus stay in the oviducts for?

Answer 39

5 days

Question 40

what can be done to treat mating induced endometritis?

Answer 40

``` (should be self limiting) uterine lavage oxytocin intrauterine antibiotics AI ```

Question 41

what is the gestation period of a mare?

Answer 41

336 days

Question 42

where does fertilisation occur?

Answer 42

ampulla of oviduct

Question 43

what does the embryo do when it enters the uterus?

Answer 43

migrates around for 15 days

Question 44

what is the migration of the embryo around the uterus essential for?

Answer 44

maternal recognition of pregnancy (prevention of prostaglandin release)

Question 45

when does placental attachment begin?

Answer 45

36 days

Question 46

what produces progesterone to maintain the pregnancy?

Answer 46

CL

Question 47

what maintains the primary CL during pregnancy?

Answer 47

eCG from endometrial cups

Question 48

how long do CLs maintain the pregnancy for?

Answer 48

first 5 months

Question 49

what maintains the pregnancy after CLs have degenerated?

Answer 49

progesterone from foetal placenta

Question 50

how early does a mare need to be aborted if breeding wants to be done again in the same season?

Answer 50

before day 35 (before endometrial cups form)

Question 51

how long after mating can a mare be put back to the stallion to see if oestrus behaviour has returned?

Answer 51

14-21 days (some still show signs if pregnant)

Question 52

what substances in blood can be used to confirm pregnancy?

Answer 52

``` eCG (45-90 days) oestrone sulphate (120+ days) ```

Question 53

what produces oestrone sulphate?

Answer 53

foetus (confirm viability and pregnancy)

Question 54

what size is the foetus for manual palpation on day 20?

Answer 54

marble

Question 55

what size is the foetus for manual palpation on day 40?

Answer 55

grapefruit

Question 56

when should a first pregnancy diagnosis scan be done?

Answer 56

15-16 days (check twins)

Question 57

when should a second pregnancy diagnosis scan be done?

Answer 57

24-26 days (heartbeat visible) - check twins and can terminate

Question 58

when should a third pregnancy diagnosis scan be done?

Answer 58

6 weeks

Question 59

when is the best time to do a pregnancy diagnosis scan if only one is being done?

Answer 59

28-35 days

Question 60

how far into gestation can transabdominal ultrasound be used for pregnancy diagnosis?

Answer 60

6 months

Question 61

what is early embryonic death?

Answer 61

death from fertilisation to day 40