Equine reproduction/neonatology Flashcards
what is a mare?
female horse over 4 years old
what is a filly?
female horse young than 4 years old
what type of breeder is the mare?
long day, polyoestrus
how long is the oestrus cycle of a mare?
21 days
how long is diestrus in the mare?
17 days
how long does oestrus last in the mare?
4-6 days
what does the recruited follicle become?
dominant
what does the dominant follicle produce?
oestrogen (induces oestrus)
how large does the dominant follicle have to be for ovulation?
> 35mm
how long after ovulation with oestrus end?
24 hours
what does the ovulation site of the dominant follicle become after ovulation?
corpus haemorrhagicum then corpus luteum
what does the CL produce?
progesterone
how long after ovulation will luteolysis occur?
15 days (prostaglandin from endometrium)
what is the transitional period?
change from anoestrus to regular cycling
how do the ovaries appear during the transitional period?
multiple small follicle (bunch of grapes)
can the mare be bred during the transitional period?
no
how can prostaglandins be used to manipulate oestrus?
induce luteolysis (oestrus commences 3-5 days later)
how can progestogens be used to manipulate oestrus?
suppress oestrus, withdrawal leads to rebound ovarian activity
what are oestrogens used for?
induce behavioural oestrus (teaser mare)
what can chorionic gonadotropin be used for?
stimulate ovulation from dominant follicle within 24 hours
what can deslorelin (GnRH) be used for?
induce ovulation in follicle >30mm within 48 hours
what is a non-hormonal way of manipulating oestrus?
photoperiod - 16 hours of light from 2-4 weeks before winter solstice
how can oestrus be suppressed in the mare?
long term progestogens intra-uterine device anti-GnRH vaccine induce long term CL (oxytocin) put in foal (then terminate)
when should the mare be mated in relation to ovulation?
24-48 hours prior
how long is the unfertilised oocyte viable for?
12 hours
how long is spermatozoa viable for?
48 hours in mares reproductive tract
what are the features found when scanning a mare in oestrus?
dominant follicle
uterine oedema
soft oedematous cervix
(behavioural signs)
how does a dominant follicle appear just before ovulation/
softens and pointing to ovulation fossa
how does the oedema of the uterus appear just before ovulation?
cartwheel oedema begins receding 24 hours prior
how long after mating should a mare be scanned?
12-24 hours (check for ovulation)
what are the important mechanisms of perineal conformation?
vulva seal
vestibular seal
cervical competence
why is perineal conformation important?
poor confirmation leads to pneumovagina causing urovagina and leading to bacterial contamination
what is done during a caslicks vulvoplasty?
suture vulva lips together as much as necessary (for poor perineal conformation)
what problem can persistant CL cause?
no oestrus (give prostaglandins)
what problem can anovulatory follicles cause?
prolonged oestrus followed by prolonged luteal phase
what are the three types of endometritis?
chronic infectious metritis
free fluid in lumen
mating induced endometritis
how long do you have to treat mating induced endometritis?
5 days (conceptus in oviduct for 5 days)
what is chronic degenerative endometrial disease?
progressive degeneration of endometrium that is replaced by fibrotic tissue
what is the gestation period of a horse?
336 days from mating (rough)
where does fertilisation occur?
oviduct
what happens once the embryo enters the uterus?
migrates for 15 days
what is the migration of the embryo around the uterus essential for?
maternal recognition of pregnancy
prevent prostaglandin release from endometrium
when does placental attachment occur?
36 days after mating (base of horn)
when does production/attachment of endometrial cups occur?
35 days after mating
what maintains pregnancy for the first 5 months?
CL secreting progesterone
what is the function of the endometrial cups?
secrete eCG to maintain CL and encourage secondary CL formation
when do the endometrial cups begin to degenerate?
day 70 (gone by day 150)
what maintains pregnancy once endometrial cups have degenerated and CLs have gone?
foetal placental progesterone
what happens to the endometrial cups if the foal dies?
cups remain (no oestrus)
how can behavioural signs be used for pregnancy diagnosis?
no oestrus behaviour and won’t accept mare 14-21 days after mating
when can eCG in blood be used to diagnose pregnancy?
day 45-90
when can oestrone sulphate in blood be used to diagnose pregnancy?
day 120 onwards (also indicated foetal viability)
how far into pregnancy usually used?
day 40
how large will the lump be at day 40 in gestation?
grapefruit
when is the best time to ultrasound scan for pregnancy diagnosis of the mare?
first scan 15-16 days
second scan 24-26 days
why is a pregnancy scan done 15-16 days after mating?
check for twins and pregnancy
why is a pregnancy scan done 24-26 days after mating?
heartbeat visible
can still terminate before endometrial cups
how far into the pregnancy can trans abdominal scanning be used to confirm pregnancy?
6 months
when does early embryonic death occur?
before day 40
what can cause early embryonic death?
congenital abnormalities
uterine infection/environment
breeding on foal heat
what is foal heat?
the first heat roughly 7 days after the mare has foaled
what are possible viral infections that can cause abortion?
equine herpesvirus 1
equine viral arteritis
bacterial (ascending infection, haematogenous)
fungus
how can abortion due to equine herpesvirus 1 be prevented?
vaccinate 5, 7, 9 months into pregnancy
what is done if a twin pregnancy is diagnosed?
abort
one twin manually crushed
how can abortion be induced before 3 months?
prostaglandin
how can abortion be induced after 3 months?
repeated prostaglandin
dilate cervix
how can foaling be induced?
oxytocin injection (large risk for dystocia/rupture)
what is prematurity?
foal born at a gestational age of <320 days with immature physical characteristics
what is dysmaturity?
full term foal with immature physical features
what are the characteristics of a premature/dysmature foal?
low birth rate short silky hair floppy ears domed head flexor tendon laxity incomplete ossification
when does maximum absorption of colostrum occur in foals?
within 8 hours of life
what are predisposing factors for the failure of passive transfer of immunity (colostrum)?
premature lactation (colostrum loss)
inadequate colostrum production
failure to ingest/absorb
when does IgG peak?
18 hours
what is given to treat failure of passive transfer over 12 hours of age?
plasma transfusion
what are the risk factors for neonatal illness?
dam health during gestation gestational/foaling environment ease of delivery gestational age at birth placental abnormalities placental transfer of immunoglobulins
how long should it take the suckling reflex to be present in foals?
within 20 minutes
how fasts should meconium be passed?
within 24 hours
what is the body temperature of a neonatal foal?
37.2-38.9 (higher than adult)
what is the heart rate of a neonatal foal?
40-80bpm
how do the normal lungs of neonatal foals sound?
harsh/loud
what is the first and most important differential of a sick neonatal foal?
neonatal septicaemia
what are the risk factors for neonatal septicaemia?
failure of passive transfer
hygiene, stress, disease, management
what are common pathogens causing neonatal septicaemia?
E. coli Actinobacillus Salmonella Streptococcus Staphylococcus (mixed)
how can organisms enter the foal to cause neonatal septicaemia?
openings (umbilicus)
open gut
inhalation
un utero
what are the clinical signs neonatal septicaemia?
off-suck and lethargy increased respiratory rate/effort dark MM petechial haemorrhage diarrhoea hypopyon meningitis lameness (swelling)
what happens during septic shock?
vasodilation
increased metabolic rate and oxygen consumption
initial increase of CO
