The mare Flashcards
(32 cards)
When does the mare begin puberty?
12-24 months old
What are the two main phases of the mares oestrus cycle?
Folicular - Oestrgen dominant
Luteal - Progesterone and PG dominant
How long is the oestrus cycle of the horse?
21 days
Describe the breeding character of the horse.
Long-day breeders - summer and autumn
Seasonal polyoestrus
Anoestrus over winter
Transitional periods at the beginning and end of the season
They cycle from puberty to death
How long does oestrus last in the horse?
4-6 days
Mare becomes unreceptive to the stallion within 12-24 hours of ovulation
How large does a dominant follicle have to be for ovulation to occur?
How does it induce oestrus?
>35mm diameter
The follicle produces oestrogens
Outline what happens in the luteal phase of the oestrus cycle.
The ovulated site becomes a CH and then a CL which produces P4
The CL is at first resistent to PG but after 15days becomes sensitive and luteolysis occurs
After this follicular waves begin to develop and oestrus occurs (2 waves before dominant follicle selected)
In a transitional period mare what would be seen on an ultrasound of the ovary?
What happens to these structures?
Multiple small follicles (10-25mm)
These follicles will not ovulate and regress - mares in this period may show off oestrus behaviour and will not concieve if mated
How long can the transitional period last?
Up to 6 weeks
Induces luteolysis if a receptive CL is present on the ovary
Exogenous prostaglandins
Oestrus will comence 3-5 days post injury
(may cause sweating, d+ or colic signs)
Supresses oestrus, withdrawal of treatment leads to a rebound in ovarian activity.
Progestagens
Induce signs of oestrus (not true) and used in teaser mares for AI collection.
Oestrogens
Induces ovulation of a dominant follicle within 24 hours of administration.
Human chorionic gonadotrophin (chorulon)
Acts like LH
A GnRH analogue which induces ovulation in 48 hours.
Deslorelin
How manipulation of photoperiod be utilised in promoting ovian cyclicity of the horse?
Extending the recieved photoperiod to 16 hours (8 hours of dark)
30 minutes extension on either end of the day 2-4 weeks before the summer solstice
Ovulation occurs 8-10weeks later
How long is equine sperm viable within the reproductive tract of the mare?
48 hours
When should you serve a mare? Why?
24-48 hours prior to ovulation
Sperm are viable for 48 hours in the mares reproductive
Oocyst is only viable for 12 hours post ovulation
How does a mares uterus and ovary appear on ultrasound when she is in oestrus?
Dominant follicle on one ovary
Uterine oedema
Soft oedematous cervix
(remember behavioural signs)
You scan a mare and find she has a 35mm DF on the left ovary and uterine oedema.
When you next scan her and why?
In 24-48 hours to check if she has ovulated
You scan a mare and find ms follicles on the left ovary and a CL on the right. There is no uterine oedema present.
How would you progress?
PG and rescan in 3-5 days - when she comes back into oestrus
You scan a mare and find a 35mm follicle with a “pointed” edge.
How would you progress?
Breed her!
The pointed DF suggests she is about to ovulate
Describe the changing formation of uterine oedema during oestrus.
- Oedema forming
- Oestrus = catwheel oedema
- Oedema decreases in 24 hours prior to ovulation
A post mating scan 24-48hrs after mating is useful why?
Check only 1 ovulation has occurred
Check she has ovulated
Checking for fluid in uterine lumen (endometritis
What three seals prevent bacterial contamination of the uterus in the mare?
Vulval
Vestibular
Cervix
