Equine Reproduction Flashcards
Describe the mare’s oestrus cycle.
Seasonally polyoestrus
Cycle from spring to autumn naturally - brought on by increasing day length
Oestrus length is 21 days
When do we begin trying to mate (cover) mares?
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
What reproductive health checks should we do before covering a mare?
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)
What is ‘teasing’?
Testing whether a mare is in season or not using a male horse
Who would we typically use to ‘tease’ a mare?
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
Describe oestrus behaviour in the mare.
Lifts tail Winking of vulva Squirts urine Wide-legged stance Acceptance of male presence Does not kick out at stallion Tolerates his attention
Describe oestrus behaviour in the stallion/teaser.
Phlemen posture Sniffs, nuzzles, then bites hindlimbs and perineum Drops penis Penile erection If permitted, will cover the mare
How can we use ultrasound to determine if a mare is in oestrus?
Uterus - large follicle (approx. 5cm diameter), uterine oedema, no free fluid in uterus
Cervix = red, engorged, saggy (in dioestrus = pale, small, tight)
What safety considerations should we have for in hand covering?
Human - hats, safety footwear, gloves
Mare - wither guard, hobbles, bridle, twitch, boots, tail bandage
Stallion - bridle/chain, lunge line, boots
What should we do after covering a mare?
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
What kind of semen can we use for artificial insemination?
Fresh - local stallion
Chilled - stallion in same country
Frozen - global possible
How can we collect semen using a dummy?
Train stallion to dummy
Artificial vagina - integral or separate
Soak towel in urine from mare in season to encourage/stand in season mare nearby
How can we collect semen using a mare?
Sedated
Ovarioectomised
In season
Questionable welfare for mare if needs restraint repeatedly
Describe an artificial vagina used for semen collection.
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
How do we carry out artificial insemination?
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)
How do we manage mares post-covering/artificial insemination?
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
Describe embryo transfer in mares.
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!
How do we diagnose pregnancy in mares?
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
How do we deal with a diagnosis of a twin pregnancy?
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
How long is a mare’s pregnancy?
Approx. 340 days (11 months 11 days), range 320-370 days
310-325 days = premature
Before 310 days = abortion (non-viable)
What are some signs of imminent foaling?
Udder development - ‘waxing up’, dripping milk, milk electrolytes (calcium increases)
Mare vulva relaxes
Foaling alarms - use sweating
Describe stage 1 labour.
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
How does a mare behave during stage 1 labour?
Restlessness Getting up and down Looking at abdomen Sweating Frequent urination
Describe stage 2 labour.
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
Describe stage 3 labour.
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
How is dystocia classified in mares?
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
What referral options do we have for dystocia mares?
Vaginal assisted delivery
Caesarean section
Embryotomy
Euthanasia
Describe passport legislation for horses.
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
How do we place a microchip in a horse?
Scan neck to ensure no existing microchip
Scan chip to ensure correct no.
Insert into nuchal ligament
Scan neck to ensure chip in situ
