Equine Reproduction Flashcards
when do fillies and colts become mares and stallions?
filly <2 years female
colt <4 years entire male
what is an embryo?
conceptus under 50 days old
what is a foetus?
conceptus over 50 days old
what type of oestrus do mares have?
seasonally polyoestrus
when doe mares naturally cycle?
spring to autumn
what is mare cycle simulated and stopped by?
brought on by increasing day length and cease as days shorten
how long is a mares oestrus cycle?
21 days
what hormone causes the regression of the corpus luteum?
prostaglandin f2 alpha
why do mares need to foal in early spring/summer?
need foal to grow before winter
UK weather is unpredictable
when should mares be covered?
during the month after the month you wish them to foal in next year
why is it advantageous for thoroughbreds to be born early in the year?
when racing they race against all horses born in the same year as them
if born later they are less mature and less strong
when do breeders aim for their thoroughbred mares to foal?
after 1st January (to avoid being very young in their year) but close to
when are thoroughbred mares covered from?
valantines day
how are thoroughbred mares manipulated to come into season early?
lights and drugs
how can ovulation be induced in mares when they are sent to stud after their foal is born?
use of prostaglandin which causes corpus luteum regression and cycle within 2-3 days
what are the pre-breeding checks performed on a mare before or when she arrives at stud?
general health (clinical exam)
presence of strangles
reproductive health
how is the reproductive health of the mare checked before or on arrival at stud?
clitoral fossa and sinus swabs
what swabs should be used for clitoral fossa and sinus swabs?
ENT as smaller
what must clitoral fossa and sinus swabs be transported to the lab in?
Amies charcoal - prevents bacterial growth
what are clitoral swabs of mares checking for?
taylorella equigenitalis
pseudomonas aeruginosa
kiebsiella
what is caused by taylorella equigenitalis?
contagious equine metritis
what is significant about contagious equine metritis?
notifiable
how must clitoral fossa and sinus samples be sent to the lab?
name, date, time and site of sample
ensure swabs in date and sample is sent quickly
what are the pre-breeding checks performed at stud?
endometrial swabs for cytology and culture and sensitivity
ultrasound scan of ovaries
ultrasound scan of uterus
what are you looking for on a pr-breeding scan of the ovaries?
follicle developmet
what are you looking for on a pre-breeding scan of the uterus?
free fluid
cysts
what is teasing?
testing whether a mare is in season (behavioral oestrus) by seeing if she is receptive to a male horse at her head or rear
what stallion is normally used as a teaser stallion?
pony stallion
often low value and cheap to keep
sometimes use the stud stallion
what are the oestrus behaviours in mares?
lifts tail winks vulva squirts urine wide legged stance acceptance of male presence doesn't kick out at stallion tolerates stallion attention
what is the response to oestrus behaviour seen by stallions?
phlemen posture (vomeronasal organ) sniffs, nuzzles then bites hindlimbs and perinuem drops penis penile erection will cover mare if allowed
when can the best time to cover a mare be determined?
ultrasound which shows larger follicle, uterine oedema that is beginning to wane and no free fluid in uterus
how large should the follicle be pre ovulation?
approx 5cm diameter
how should the mare be prepped when viewing her cervix?
clean perineum with warm soapy water - no hibi or iodine
how is cervix visualised?
speculum and torch
what does the cervix look like during oestrus?
red
engorged
saggy
what does the cervix look like in dioestrus?
pale
small
tight
high up off vestibule floor
what method of covering must be used to be weatherbys registered?
natural (AI not permissable)
covering certificate will be issues
what may the stallion handler do during covering to ensure ejaculation has occurred?
palpate ventral penis
when does in hand covering occur?
once teasing and scanning has determined appropriate time
what safety equipment is needed for covering in hand?
human - hat, gloves, boots
mare - wither guard, hind boots, bridle, hobbles, tail bandage
stallion - specific bridle/chain, lunge line, fore feet boots
what should be done the day following covering?
tease or ultrasound to see if still in oestrus
what will happen if the mare is still in oestrus following covering?
may cover again (ideally every other day of oestrus)
what will happen if the mare is not in oestrus following covering?
manage as normal
tease again from 18 days
ultrasound from 12 days to see if pregnant
where does unassisted covering occur?
in herd or individual
short term or permanent (e.g. native herds)
free in field and supervised
how is unassisted covering managed?
timings determined by horses
less control / human intervention
natural
unsure fo exact dates
what are the 3 types of AI semen available?
fresh - local stallion
chilled - stallion in country
frozen - globally
how is semen collected for AI?
using a dummy and AV (integral or separate)
use towel soaked in in season mares urine or have an in season mare nearby to encourage stallion
is semen collection often performed using a mare?
no - ethically questionable
need sedation and repeated restraint
dummy much more common
what is found in an artificial vagina?
filled with warm water lined lubricated insulated semen collection vessel on end filter between chamber and semen collection pot
what temperature should the water in an AV be?
crucial
38 degrees but varies between stallions
what must not be mixed with semen in an AV?
water - will destroy semen
what may be included to preserve semen?
extender - acts as a buffer to stabilise sperm
how is timing of AI managed?
based on ultrasound scans when a large follicle is present in the ovary
if ovulation is induced how can AI be managed?
fixed time insemination 36-40 hours after injection of HCG
what is the typical dose of sperm AI?
100-500 x10^6 progressively motile sperm
how is AI performed?
use speculum or hand per vaginum to guide catheter in
place catheter inside uterus through cervix
instill semen
where are the 2 main locations semen may be placed in the uterine body?
conventional (60 cm catheter) deep horn (75cm catheter)
how is the mare managed post covering / AI?
removal of free fluid associated with semen, extender and inflammatory reaction
vulvoplasty / caslicks procedure if needed
monitor with ultrasound
ensure uterus is ready for implantation of uterus within 5 days
how is removal of free fluid associated with semen, extender and inflammatory reaction performed in the mare post covering / AI?
lavage with sterile isotonic fluid (Hartmann’s)
induce uterine contractions and encourage movement to hepl remove fluid
what is the purpose of a vulvoplasty / caslicks procedure?
prevent air, faecal material from entering vestibule and causing ascending infection
when is embryo transfur performed?
on a 7-10 day blastocyst
what is complex about embryo transfer?
donor and recipient must be synchronised
requires expertise
expensive
how is pregnancy diagnosed?
ultrasound
failure to return to oestrus
blood sample
urine sample
when can ultrasound confirm pregnancy in horses?
12 days but care with twins so many wait till 14-16 days
when does failure to return to oestrus indicate pregnancy?
at 21 days post covering
when can blood samples show pregnancy in mares?
equine corionic gonadotrophin at 60 days
oestone sulphate from 120 days
what is the advantage of oestone sulphate over equine chorionic gonadotrophin in diagnosing pregnancy?
indicator of live foal as it is produced by foetal placental unit
eCG can be raised with pseudopregnancy
when can a urine sample indicate pregnancy?
from 120 days - placental oestrogens
what are the conception rates in horses?
approx 80%
why are twins so often aborted?
when demands of foals exceed placental surface area capacity to provide required nutrients and oxygen
how may twins be born?
non - identical
rarely survive - often abort
may be mummified foetus born with live foal
what should be done if twins are identified on ultrasound?
one or both should be terminated
how is termination of twins performed?
pinching of one at 14-18 days
prostaglandin to terminate both
what is the risk with pinching one twin?
may terminate both
when must a twin be terminated?
before endometrial cups sustain pregnancy (day 35) otherwise both must be terminated
what should a mare with twins be scanned for following pinching?
check there is a single one remaining
look if there are uterine cysts
how long does pregnancy last for?
~340 days / 11m 11d
when is a foal classed as premature?
310-325 days
when is a foal non-viable?
earlier than 310 days - abortion
what are the signs of imminent foaling?
udder development - waxing up, dripping milk
mares vulva relaxes
increased sweating (foaling alarms)
is dystocia common in horses?
no - usually rapid and uncomplicated delivaries
what must be done if complications do arise during foaling?
rapid action to save foal and mare
c-section is possible under GA
how long does stage 1 last for in mares?
1-4 hours
what occurs during stage 1 of labor?
foal enters pelvic canal
stimulation of dilation of cervix and vagina
progressive uterine contractions of increasing strength run from tip of uterus to cervix to psuh foal and placenta in correct direction
what are the signs of stage 1 labour in mares?
restless getting up and down looking at abdomen sweating frequent urination
what should be done while the mare is in stage 1 labour?
wash perineum
bandage tail
reverse caslicks (epesiotomy)
how long does stage 2 of labour last for?
15 to 30 mins max
what happens during stage 2 of labour?
allantois ruptures at cervical star releasing fluids
strong contractions from uterus
voluntary contractions from abdomen
amnion becomes visible with foal inside
foal presents 2 forefeet and head
hindlimbs will remain in uterus while mare rests
what does the time while the mare rests with the hindlimbs of the foal undelivered do?
gives time for blood to return from the placenta to the foal
what happens when the mare stands after the foal is delivered?
umbilicus breaks
how long does stage 3 of labor last?
<3 hours
what happens during stage 3 of labour?
contractions of uterus from tip to cervix to invert placenta and expel it along with lochia (fluids)
what should you do if the placenta has been retained for more than 3 hours?
urgent veterinary advice sought
can cause endotoxaemia and laminitis
how many layers does the equine placenta have?
6
what are the 6 layers of the equine placenta?
chorionic capillary epithelium chorionic connective tissue chorionic epithelium endometrial epithelium uterine connective tissue uterine capillary endothelium
what layers of the placental are the foetal membranes?
chorionic capillary epithelium
chorionic connective tissue
chorionic epithelium
what are the maternal layers of the placenta?
endometrial epithelium
uterine connective tissue
uterine capillary endothelium
what type of placenta do mares have?
epitheliochorial
what does a non-deciduate placenta mean?
fetal and maternal layers are seperate
what is a diffuse placenta?
one with villi spread over virtually all of the placenta apart from endometrial cysts, cervical star or twin to twin contact
what must be ensured about the placenta?
is passed in entireity
how can you be sure the placenta has all been passed?
collect from stable before traumatised
examine external and internal surface
fill with fluid to see if there are any tears - indication of complete removal
where is a placenta likely to be retained?
non-pregnant uterine horn
what is the 1, 2, 3 rule of foals?
stands in 1hr
drinks in 2hr
placenta passed in 3hr
what is defined as dystocia in mares?
once allantochorion ruptures (water breaking0
no amnion or foal at vulva within 5 mins
no strong contractions within 10 mins
foal makes no progression over a 5 minute period - viewed or palpated
what are the options if dystocia occurs?
vaginal assisted delivery controlled vaginal delivery c-section embryotomy euthanasia of mare following crash c-section under GA
if using vaginal assisted delivery when should referral occur?
if no progress within 5minutes
if not out in 30 minutes
what is the treatment of dystocia determined by?
cost
live foal/dead foal
owner
vet
what can happen while a controlled vaginal delivery is taking place within hospital?
mare will be prepped for a c-section in case the vet cannot deliver the foal vaginally
what position is best for controlled vaginal delivery in the hospital setting?
GA
hindlimbs elevated to allow the foal to be manipulated
what does the survival of c-section in an emergency depend on?
time of onset of stage 2 and proximity to hospital so speed of delvary
what are the survival rates for elective C-section?
90% survival of mare and foal
what horses require a passport?
all horses born after 2005
what horses must be microchipped?
all horses applying for passport since 2009
since 2018 what has been the rule about microchips?
all horses now need a microchip irrespective of time of birth and passport
what regulations govern passports?
horse passports regulations 2009
what is issued to a horse with it’s passport?
unique 15 digits life number
what is a passport required for?
travel
selling the horse
slaughtering
what section of the passport declares whether a horse is fit for human consumption?
section IX or 2
who can issue passports?
many passport issuing organisations (PIO) breed discipline colour may be studbook inclusion
what are the 2 registers governed by wetherbys?
thoroughbred
non-thoroughbred
when should the application for a passport be made after the horse is born?
december 31st of year born
when foal is 6 months
whichever is later
what is required on the passport application form?
owner details microchip number ID certificate (can include photos) owner and competant authority vet stamp
where are microchips placed in horses?
into nuchal ligament
describe how to place a microchip in a horse?
scan neck to ensure no chip present
scan chip to check the number
insert the chip into the nuchal ligament
scan neck to check placement
