Equine Reproduction

Question 1

Describe the mare’s oestrus cycle.

Answer 1

Seasonally polyoestrus
Cycle from spring to autumn naturally - brought on by increasing day length
Oestrus length is 21 days

Question 2

When do we begin trying to mate (cover) mares?

Answer 2

Thoroughbreds = from Valentine’s Day (to ensure born early into New Year, and therefore raced with a maturity advantage)
Mares manipulated to cycle early with lights/drugs
Covering for performance/pleasure breeds starts later than thoroughbreds

Question 3

What reproductive health checks should we do before covering a mare?

Answer 3

Clitoral fossa and sinus using ENT swabs in Amies charcoal
Label with name, date, time and site
Endometrial swabs (plain) - cytology (slide) / culture and sensitivity (charcoal)
Ultrasound - ovaries (follicle development) and uterus (free fluid/cysts)

Question 4

What is ‘teasing’?

Answer 4

Testing whether a mare is in season or not using a male horse

Question 5

Who would we typically use to ‘tease’ a mare?

Answer 5

Usually a low value, often pony stallion
Cheap to keep, less consequence if injured, may cover nanny mares to keep him interested
May use the stud stallion

Question 6

Describe oestrus behaviour in the mare.

Answer 6

Lifts tail
Winking of vulva
Squirts urine
Wide-legged stance
Acceptance of male presence
Does not kick out at stallion
Tolerates his attention

Question 7

Describe oestrus behaviour in the stallion/teaser.

Answer 7

Phlemen posture
Sniffs, nuzzles, then bites hindlimbs and perineum
Drops penis
Penile erection
If permitted, will cover the mare

Question 8

How can we use ultrasound to determine if a mare is in oestrus?

Answer 8

Uterus - large follicle (approx. 5cm diameter), uterine oedema, no free fluid in uterus
Cervix = red, engorged, saggy (in dioestrus = pale, small, tight)

Question 9

What safety considerations should we have for in hand covering?

Answer 9

Human - hats, safety footwear, gloves
Mare - wither guard, hobbles, bridle, twitch, boots, tail bandage
Stallion - bridle/chain, lunge line, boots

Question 10

What should we do after covering a mare?

Answer 10

Tease or ultrasound scan the following day
If still in oestrus, may cover again - usually every other day
If not in oestrus, manage as normal - tease again from 18 days, ultrasound from 12 days

Question 11

What kind of semen can we use for artificial insemination?

Answer 11

Fresh - local stallion
Chilled - stallion in same country
Frozen - global possible

Question 12

How can we collect semen using a dummy?

Answer 12

Train stallion to dummy
Artificial vagina - integral or separate
Soak towel in urine from mare in season to encourage/stand in season mare nearby

Question 13

How can we collect semen using a mare?

Answer 13

Sedated
Ovarioectomised
In season
Questionable welfare for mare if needs restraint repeatedly

Question 14

Describe an artificial vagina used for semen collection.

Answer 14

Filled with warm water - temp. is vital and varies by stallion
Lined, lubricated, insulated
Semen collection vessel insulated
Filter gel from semen
Do not get water in semen

Question 15

How do we carry out artificial insemination?

Answer 15

Timing usually based on ultrasound scans
Using speculum to visualise/hand per vaginum to guide
Place insemination catheter through cervix into uterus
Instil semen dose into uterine body (typically 100-500 million progressively motile sperm)

Question 16

How do we manage mares post-covering/artificial insemination?

Answer 16

Removal of free fluid associated with semen/extender/inflammatory reaction - lavage with sterile isotonic fluid, induce uterine contraction, encourage movement
~5 days to achieve an ideal environment
Monitor with ultrasound

Question 17

Describe embryo transfer in mares.

Answer 17

7 to 10-day-old blastocyst, collected from donor mare and transferred to recipient mare
Requires expertise and experience
Synchronise donors and recipients
Expensive but possible!

Question 18

How do we diagnose pregnancy in mares?

Answer 18

Ultrasound scan from 12 days (beware of twins this early)
Failure to return to oestrus at 21 days
Blood sample from 60/120 days
Urine sample from 120 days

Question 19

How do we deal with a diagnosis of a twin pregnancy?

Answer 19

If identified on ultrasound scan terminate one or both
‘Pinching’ - easiest before implantation at 14-18 days, may kill both
Must terminate before endometrial cups sustain pregnancy (35 days) - use prostaglandin
Always scan again to ensure a singleton
Differential diagnosis = uterine cysts

Question 20

How long is a mare’s pregnancy?

Answer 20

Approx. 340 days (11 months 11 days), range 320-370 days
310-325 days = premature
Before 310 days = abortion (non-viable)

Question 21

What are some signs of imminent foaling?

Answer 21

Udder development - ‘waxing up’, dripping milk, milk electrolytes (calcium increases)
Mare vulva relaxes
Foaling alarms - use sweating

Question 22

Describe stage 1 labour.

Answer 22

Duration 1-4hrs
Foal enters pelvic canal, stimulating dilation of cervix and vulva
Uterine contractions of increasing strength from tip to cervix
Time to - wash perineum, bandage tail, reverse vulvoplasty

Question 23

How does a mare behave during stage 1 labour?

Answer 23

Restlessness
Getting up and down
Looking at abdomen
Sweating
Frequent urination

Question 24

Describe stage 2 labour.

Answer 24

Duration 15 mins
Allantois ruptures at cervical star, releasing fluids
Strong contractions from uterus and voluntary abdominal contractions
Amnion then visible with foal inside
Foal presents 2 toes and nose, shoulders and body of foal expelled
Hindlimbs retained in uterus, mare rests - time for blood to return from placenta to foal
When mare stands, umbilicus breaks

Question 25

Describe stage 3 labour.

Answer 25

Duration < 3hrs
Uterine contractions from tip to cervix
Inverts placenta and expels it and lochia (fluids)
If placenta retained >3hrs seek urgent veterinary advice as retained foetal membranes may cause endotoxaemia

Question 26

How is dystocia classified in mares?

Answer 26

Once allantochorion ruptures (i.e. water breaking):
No amnion or foal at vulva within 5 mins
No strong contractions within 10 mins
No progression of foal made over a 5 min period

Question 27

What referral options do we have for dystocia mares?

Answer 27

Vaginal assisted delivery
Caesarean section
Embryotomy
Euthanasia

Question 28

Describe passport legislation for horses.

Answer 28

All horses born since 2005 require a passport
All horses need microchips
When passport issued, each horse given a unique 15-digit life number
Passport required to - travel with/sell/slaughter horse
Application to be made by December 31st of year foal born/when foal is 6 months old, whichever is later

Question 29

How do we place a microchip in a horse?

Answer 29

Scan neck to ensure no existing microchip
Scan chip to ensure correct no.
Insert into nuchal ligament
Scan neck to ensure chip in situ