This document discusses equine reproduction, covering topics like mare anatomy and physiology, pre-breeding plans, breeding plans, complications that can arise, embryo transfer, and gestation. Specifically, it describes the reproductive organs of mares, their estrus cycles, ultrasound exams during breeding, artificial insemination procedures, common breeding complications and their treatments, the history and process of embryo transfer, and what to expect during a mare's 11-month gestation period. It also addresses the variables that can affect the duration and costs of a breeding plan.

1. Equine Reproduction
Tad Thompson, DVM
Sheridan, IN

2. Topics For Tonight
– Mare
• Anatomy & Physiology
• Prebreeding Plan
– Months, Weeks & Days
• Breeding Plan
– Stallion
• What's The Options
– Complications
– Embryo Transfer
– Gestation
• Now What?
– How Long & How Much

3. Mare Anatomy & Physiology
What are the reproductive organs of the mare?
• Pineal Gland
• Hypothalamus
• Pituitary Gland
• Reproductive Tract
– Ovaries, Ovaducts, Uerine Horns, Uterine Body, Cervix, Vagina, lymph
• Mare’s Udder
– Take home message: Endocrinology is a big player in
reproduction
– Because of this complexity of the endocrine system,
mares are considered to be ______ ______ Breeders

4. Mare Anatomy & Physiology
–Long Day Breeders
• Responsive to the photo period to induce estrus
– Photic information is received by the retina,
transferred to the hypothalamus, which instructs the
rest of the endocrine organs.

5. Mare Anatomy & Physiology
Mares require day light at least 14.5 hours per day to
start vernal transition from anestrus.
Recommend 18 hours per day of artificial lighting
• Best to extend lights in the evening
• Rule of thumb can you sit in the darkest corner of the stall
and read a newspaper?

6. Mare Anatomy & Physiology
? What are the seasonal stages of the mares cycle?
– Winter months (Anestrous)
– Early Spring (Vernal Transition)
– Later spring through summer (Estrous)
– Fall (Transition)
– All mares will go through a transitional period of 6-8 weeks
– Naturally early April is first heat cycle, on average
– What does it mean for your mare to be “Transitional”?
• Her cycle will not progress to the breeding stage.

7. Mare Anatomy & Physiology
? What are the stages of the mares estrus cycle?
– Estrous (follicular phase)
– Diestrus (luteal phase)
Estrous defined as the period in which the mare is
sexually receptive to the stallion, the genital tract is
prepared to accept and transport spermatozoa, and
ovulation occurs.
Average cycle length for mares = 21 days.

8. Mare Anatomy & Physiology
Estradiol increases
during estrus
- Produced by the
Follicle
- Rapidly declines at
ovulation
- Creates the “Edema”
seen on ultrasound
- Relaxation of cervix
- etc……

9. Mare Anatomy & Physiology
Progesterone is
produced by the CL and
increases post OVD
-Maintains pregnancy
-Regumate is a synthetic
progesterone source.
PGF2alpha is a natural
prostaglandin that causes
the CL to regress
-Estrumate & Lutalyse are
prostaglandins

10. Methods Of Synchronization
• PGF2 (Lutalyse, Estrumate)
• Combine exogenous progesterone
(Regumate) with PGF2
• P & E with PGF2
• All followed with hCG or Deslorelin to
induce ovulation. Goal is to induce
ovulation within 48hrs.

11. Mare Anatomy
Good Challenging

12. Prebreeding Plan
1. Determine foaling date goal.
2. Does the mare need under lights?
3. Any history of prior complications?
1. If so start early – more to come
4. Select stallion.
1. Determine shipping options – more to come
5. Make sure paper work is in order.
.

13. Breeding Plan
Once mare is cycling what do I do?
Rectal ultrasound
Uterine culture and cytology
Cervix evaluation
Tools that help guide us in optimizing the breeding.

14. Breeding Plan
Rectal ultrasounds
“Making since of the Black & White”
What are we looking at?
A. Cervix
B. Uterine body
C. Both uterine horns
D. Both ovaries
– Cross section of a uterine horn

15. Breeding Plan
Rectal ultrasounds
“Making since of the Black & White”
– Mares in estrus will have the following ultrasound
characteristics
– Uterine body & horns 
• Pin Wheel Appearance
» No Free Fluid
– Ovaries – Large Follicule
» Black in color with a clear internal structure
– Cervix is soft and open

16. Breeding Plan
Rectal ultrasounds
“Making since of the Black & White”
– Mares in anestrus will have the following ultrasound
characteristics
– Uterine body & horns will have no edema
• Homogeneous look
» No Free Fluid
– Ovaries 
• CL or corpum lutem
– White structure
– Producing Progesterone
– Cervix is tight & closed
– Progesterone affects

17. Breeding Plan
How Do We Get Her Bred?
• The Stallion
A. Live Cover?
B. Artificial Insemination?
– Semen Type
• Fresh
• Cooled
• Frozen
– Semen Quality
• Concentration
• Motility
• Morphology
We will evaluate each sample prior to insemination

18. Breeding The Mare
• Standard breeding management apply
– Sterile prep of rectal and vaginal area
– Sterile OB sleeve, pipette and lube
– Semen is deposited inside internal os of cervix unless
frozen semen
– Frozen semen
• Breeding close to OVD
• Deep horn insemination
• Pre & post OVD

19. Questions???
So Far!

20. Complications
– Abnormal conformation
• Urine pooling
• Fecal contamination No Bugs Needed 
– Uterine infection
• Semen infection
– Poor uterine clearance of fluid
• Poor lymphatic drainage
• Cervix issue
– Cervical incompetence
• Failure to open & close
• Higher rate of yeast & fungal infections
– Anovulatory follicles
• More frequent in transitional mares but
may occur mid summer

21. Complications
– Abnormal conformation
– Uterine infection
– Poor uterine clearance of fluid
• Culture & cytology
– Know what you are dealing with
• Uterine lavage
– solution to pollution is dilution
• Oxytocin
• +/- Antibiotics
– Cervical incompetence
• If no infection topical medication to soften cervix
– Anovulatory follicles
• Time
• Later prostaglandin

22. Transcervical Uterine Lavage

23. Questions
• My Padawan Learners

24. History of Embryo Transfer
• What species was the
first ET preformed
on?
• Rabbit
• What year was the
first ET preformed?
• 1891

25. Embryo Recovery
• Mare are bred in the same fashion
• Embryos can be recovered b/w day 6-9
– Embryo enters uterus around @ 6.25days post OVD
– Older mares slower embryo transient time
• Optimal recovery time varies based on goals
– i.e. fresh transfer vs. vitrification
– Recovery rates of 70-80 % can be expected @ day 7-
8 post ovulation
– Transfer of larger day 9-10 embryos is possible but
less reliable
• Increased Size and Fragility
• Use modified technique

26. Transcervical Uterine Lavage

27. Recovered Fluid
• Filter cup emptied into sterile girded
search dish
– Rinse filter with flush media
• Fluids examined with
stereomicroscope
– 10-15x magnification
– Day 7 embryo’s 300-600 um dia.
– Large embryo’s (~8day) often visible with
naked eye

28. Staging Embryo

29. Grading Embryo
Grade 1
Grade 3

30. Transfer Process
• The single most rate limiting step in the
success of the ET program
» The Transfer!!!
• This process is achieved in a manor
similar to artificial insemination with a
success rate ranging from 60% to 80%
– Technique experience very important

31. Summary of Success
• If stallion and mare factors optimized
– Good donor candidate
• 75% embryo recovery
• 75% pregnancy rate at 14 days
• 5-10% early pregnancy loss
• Approx. 50% success or 1 out of 2 flushes
– National averages
– On the conservative side

32. Gestation
– Pregnancy check at 14-16 days post OVD
• Prior to implantation – twin reduction
• Return to estrus for rebreeding
– Recheck ultrasound 30-45 days
• Early embryonic loss
• Breed back
– Recheck at 90-120 days - optional
• Fetal sexing – variable results, fetal size and position
– Recheck 300 day or 10 month - optional
• Early placentitis diagnosis
– Low frequency

33. Gestation
Main causes of abortion in mares
• EHV – 1 : single most important infectious cause
– Viral respiratory infection of the mare followed by
transplacental migration and ultimate anoxia of foal
– Variable duration of infection and abortion
• Bacterial & Fungal Infection
– Most commonly ascending through cervix
– Placentitis – inflammation of placenta
• Generally bacterial infection
• Clinical signs include
– Premature mammary development with milk production
– 300 day ultrasound may help catch 50-60% of these case resulting in a
live foal

34. Gestation
– Vaccination schedule
• EHV – 1 at months 3, 5, 7, 9
• Prefoaling boosters 30 days prior to delivery
– Rhino/ Flu, WNV, EWT, Rabies
– Improves colostrum quality

35. Take Home Message
Reproduction is all about the
“half percenters”
!They soon add up to a significant difference!

36. How Long & How Much
Breeding Plan
A. Live cover
B. JVC manages from A-Z
C. Mare owner hauls in
D. Difficult mare has prolonged stay
Many variables can affect duration and cost of breeding

37. How Long & How Much
Board Dry Mare = $29
Wet Mare = $32
Uterine Culture = $75
Uterine Cytology = $66
Ultrasound (In Clinic)
- first one of the year $52
- followup $29
Semen Evaluation = $19
Artificial Insemination Fresh semen = $49
Frozen semen = $80
Uterine Lavage = $72
Uterine Infusion = Varies based on antibiotic

38. How Long & How Much
Prebreeding Workup Uncomplicated Breeding Hauled In
-Uterine culture & cytology -Less board at JVC
-Ultrasound exam Average cost $475
Average cost $190
Complicated Breeding
-Based in reason & number of
Uncomplicated Breeding treatments
-Mare arrives in estrus Average cost is highly variable
-can double base costs
-No treatments needed
-We manage A – Z Embryo Transfer
-4 days in clinic -Collection at JVC $410
Average cost $450 -Recipient mare off site $?

39. Questions???

40. 317-758-4865
janssenvetclinic.com
Tad Thompson, DVM