Equine reproduction Flashcards
horse breeding year
- spring to autumn cycle (brought on by longer days)
- mares are seasonally polyoestrus
- 21 day cycle
when to plan for a mare to foal
late spring/summer
- foal can grown before winter
- mares and foals are easiest maintained at grass
how long is mare pregnancy
320-370 days
- 310-325 days= premature
- nonviable before 310 days
UK thoroughbred breeding year
- they race against other 2&3 year olds in their same calender year
- those born soonest after jan 1st will be more mature and have an advantage
- mares covered from valentines day and manipulated to cycle early with light and drugs
pre-breeding checks before arrival at stud
- general health (strangles, clin exam)
- reproductive health (clitoral fossa and sinus swab)
- submitted in amies charcoal
- labelled with name, date, time, site
pre-breeding checks at stud
- endometrial swabs
- ultrasound of ovaries (follicle development)
- ultrasound of uterus (free fluid, cysts)
teasing
to test if mare is in season
- care needed if previous foal is present (foal at foot)
- teaser usually low value, pony stallion (less consequence if injured, cheap to keep)
- may cover nanny mares to keep him interested
oestrus behaviour- mare
- lifts tail
- winking of vulva
- squirts urine
- wide legged stance
- acceptance of male presence and attention (no kicking)
oestrus behaviour-stallion
- phlemen posture (increases exposure of pheromones)
- sniffs, muzzles then bites hindlimbs and perineum
- drops penis, becomes erect
- if permitted will cover mare
oestrus ultrasound
- determines the best time to cover (less covers needed to be successful)
- large follicle (5cm)
- uterine oedema
- no free fluid in uterus
cervix during oestrus
- clean with warm soapy water only
- visualise with speculum and torch
oestrus- red, engorged, saggy
dioestrus- pale, small, tight
natural covering- in hand
- a must for thoroughbreds, AI not permissible to be registered
- stallion walked to mare from behind and allowed to greet
- stallion handler may palpate ventral penis for ejaculation
safety for mare and stallion during covering
mare: wither guard, hobbles, bridle, twitch, boots, tail bandage
stallion: bridle, lunge line, foot boots
after covering…
tease or ultrasound scan following day
- if still in oestrus: cover again
- if not in oestrus: tease again after 18 days, ultrasound from 12 days
unassisted covering
- in herd or living in herd, common with native breeds
- timings determined by horses
semen for AI
fresh semen- local stallion
chilled semen- stallion in same country
frozen semen- global possible
semen collection for AI
- train stallion to dummy
- soak towel in urine from mare in season to encourage
- stand in season mare nearby
artificial vagina
- filled with water slightly higher than body temp (38 degrees)
- lined, lubricated, insulated
- filters gel from semen
artificial insemination
- insemination occurs when large follicle seen on ultrasound
- fixed time insemination can be used if ovulation is induced
- dose with 100-500 X10^6 sperm
post covering/AI management
removal of free fluid associated with semen
- lavage with sterile saline
- induce uterine contraction
- encourage movement
vulvoplasty caslicks proceedure
- prevents ascending infection
embryo transfer
- 7-10 day blastocyst
- collect from donor mare to transfer to recipient mare
pregnancy diagnosis
- ultrasound scan from 12 days (beware twins this early)
- failure to return to oestrus at 21 days
- blood sample from 60 days (PMSG)
- blood sample from 120 days (oestrone sulphate)
- urine sample from 120 days (placental oestrogens)
twins
- usually not identical
- rarely survive to full term
- aborted between 5-7 months when demands exceed placental surface area capacity to provide required nutrients and oxygen
pinching of twins
- if twins identified, pinching is necessary to terminate one or both
- must terminate before endometrial cups sustain pregnancy (d. 35)
- prostaglandin given to terminate whole pregnancy if pinching unsuccessful
signs of imminent foaling
- udder development (dripping milk, increase in calcium levels through electrolyte monitoring)
- vulva relaxes
- sweating
foaling
- usually rapid and uncomplicated
- survival requires rapid identification and resolution of complications
- c-sections possible under GA
stage 1 labour
- 1- 4hrs
- foal enters pelvic canal stimulating dilation of cervix and vulva
- uterine contractions of increasing strength from tip to cervix
stage 1 labour behaviour
- restlessness
- looking at abdomen
- sweating
- frequent urination
what to do during stage 1 labour
- wash perineum
- bandage tail
- reverse caslicks (cut through tissue that was previously sutured)
stage 2 labour
- 15 mins
- allantois ruptures at cervical star releasing fluids
- strong contractions from uterus and voluntary abdominal contractions
- amnion visible with foal inside
- shoulder and body expelled
- hindlimbs retained and mare rests
- blood returns from placenta to foal
stage 3 labour
- <3 hrs
- uterine contractions invert placenta and expels it and lochia (fluid)
- if longer than 3hrs seek urgent advice
placenta 6 layers
fetal layers:
1. chorionic capillary endothelium
2. chorionic connective tissue
3. chorionic epithelium
maternal layers:
4. endometrial epithelium
5. uterine connective tissue
6. uterine capillary endothelium
- non-deciduate (fetal and maternal layers seperate)
- diffuse (villi spread over virtually all the placenta)
placenta care
- ensure passed in entirety
- collect from stable before traumatised
- examine both surfaces
- distension with fluid possible if no tears
- shows complete removal
dystocia
once allantochorion ruptures:
- no amnion or foal at vulva within 5 mins
- no strong contractions within 10 mins
- no progression of foal made over 5 min period
dystocia options
- vaginal assisted delivery
- refer if no progress in 5 mins or foal not out in 30 mins
- c-section
- embryotomy
- euthanasia
determined by cost, live/dead foal
controlled vaginal delivery
- hindlimbs raised so foal moves further up the abdomen allowing vet to reposition foal
- nurse team prepare mare for c-section as last case scenario
c-section
- elective (90% mare and foal survival)
- emergency (survival related to time of onset of stage 2 labour)
foal 1, 2, 3 rule
1: foal stands within 1hr
2: suckles within 2hrs
3: placenta passed within 3hrs
passport legislation
- all horses born since 2005 require passport
- all horses must be microchipped
passport
- unique 15 digit number given to each horse
required to: - travel with horse
- sell horse
- slaughter horse
microchip placement
- into nuchal ligament
1. scan neck to ensure not placed already
2. scan chip to ensure correct number
3. insert
4. scan neck to ensure in situ
