184 Pages 132 Color Illustrations
    by Teton NewMedia

    This book briefly reviews the history of equine embryo transfer, covering in clinically practical terms the techniques, equipment, and management protocols currently in use. Embryo transfer has become a big business, especially for breeding racing stock (horses and camels), and is therefore a very important aspect of equine practice. Ed Squires and Pat McCue have been involved with the development of embryo collection and transfer procedures since the early 60s and have both contributed important techniques and innovations to the process through their research and clinical experience. This book captures the clinical experience, so far, and applies it directly to equine practice. The book is of great value to general equine practitioners for reference, equine reproduction specialists, animal science at the graduate level (equine track), and breeders.


    1. Introduction
    General Introduction (i.e. what is ET)
    Advantages and uses of embryo transfer
    Changes in the ET Industry
    Breed regulations (include a Table of most major breeds; ET, frozen embryos, etc.)
    Per cycle ET Success = Embryo Collection Rate (50-60%) x Embryo Transfer Pregnancy Rate (70-80%)
    Goals of the Manual
    2. History of equine embryo transfer
    Domestic horses as surrogates for endangered equids(?)
    3. Reproductive Anatomy and Physiology of the Mare
    Anatomy of the mare
    Physiology of the estrous cycle
    Physiology of early embryonic development and early pregnancy
    4. Management of the donor mare
    Selection of the donor
    Evaluation of the donor (BSE)
    Management and Day of breeding (fresh, cooled, frozen semen)
    Palpation/ultrasound examinations relative to flush; daily vs every 6-8 hrs for frozen semen; BID if goal is to collect a small embryo at day 6.5 for cryopreservation
    Induction of ovulation (hCG and deslorelin)
    Donor mare management (PMIE, fluid, etc.)
    Estrous cycle control (Lights, P&E, PGF, hCG, Deslorelin, Regumate)
    Allow a mare to carry to term by approximately 10 years of age
    Allowing mare to carry own every 3-4 years
    Effect of repeated flushing on uterine health and embryo recovery
    # flushes per year recommended
    Fertility of mares after flushing (i.e. same season)
    Problem mares (i.e. PMIE, etc.)
    Maiden mares (young vs older)
    Post partum mares (i.e. flushing on foal heat)
    5. Superovulation
    Optimal follicle size at onset…
    Problems – same stallion vs. goal of different stallions
    Not every mare responds to FSH
    PAF’s and HAF’s
    6. Embryo Collection
    Equipment (Box Table)
    Facilities (stocks vs stall, etc.)
    Procedure; (incl. clean out and wash up)
    Ultrasound prior to flush in problem mares (PMIE) for fluid detection
    Day of flush – options day 6.5, 7, 8, 9
    Fluid volumes relative to maiden, open and post-foaling mares
    Number of lavages per flush attempt
    Rectal manipulation of uterus to move fluid around (massage)
    Direct visualization of embryos in cup
    Looking for embryos after each lavage
    Techniques (Standard vs French, Fernando Rivera)
    Medications (oxytocin, sedation, buscopan, etc.)
    Reflush option (Extra flush same day standard; next-day reflush option; superovulation reflush (≥ 50 % embryo recovery relative to ovulation guideline)
    PGF after flush; why (luteolysis – clean up and avoid unwanted carry-own pregnancy); what happens if you do not; option to let mare carry
    7. Factors affecting embryo recovery
    Donor age and reproductive status
    Day of recovery
    Number of flushes
    Stallion effects
    Number of ovulations (single vs. spontaneous multiple, superovulation)
    Effect of ovulation rate and side of multiple ovulations on recovery rate (Fernando Riera data)
    Synchronization of ovulations – embryo size and recovery
    Reflushing (same day, next day)
    8. Embryo Handling
    Equipment – straws, dishes (size, round vs square)(Box Table)
    Search procedures
    Debris in dish (how to handle)
    Miscellaneous items in dish
    Swirling dish
    Embryo size expected
    Embryo morphology expected
    Hints regarding bubbles, etc. (swirl, let contents settle, then aspirate bubbles along edge)
    9. Washing and holding embryos
    # and sizes of drops
    Types of holding media; how long to hold a fresh embryo
    Types of wash dishes (flat vs round bottom)
    Storage vessels (dishes vs straws)
    10. Evaluation of embryos
    Lots of photographs and drawings
    ET Log (flush and transfer logs)
    11. Cooled Storage and Transport of Embryos
    When to cool (i.e. how many hours between flush and transfer)
    Cooled embryo technique
    Time limit for holding embryos
    Media available (types; buffer systems, etc) Ham’s F-10
    12. Cryopreservation of Embryos
    History of embryo freezing
    Slow freeze vs Vitrification
    Selection of embryos (flush days, embryo size, etc.)
    Vitrification technique (supplies, method)
    Storage of vitrified embryos
    Warming and transfer
    Pregnancy results
    13. Management of Recipient mares
    What makes a good recipient
    Selection – age, size, parity, temperament, physical health
    History of mares (barren, maiden, foaling)
    Examination schedule
    Examination of recipients – 5 day check; pass system
    Housing recipient mares
    Synchronization options (new data from perla); general ‘window’ of synchrony (+1 to -3 or -4)
    Line up recipient with embryo characteristics (fine tune)
    Recipient:Donor Ration (3:1) for synchronization
    Individual recipient for single donor (1:1) – how to manage
    ‘Floating’ recipient herd
    Synchronization schemes
    Optimal day(s) of transfer
    Management after transfer (housing, hormones, etc.)
    Use of non-cycling, ovariectomized, XO and pregnant mares as recipients
    Using the donor mare as her own recipient (in the event of twin embryos)
    14. Transfer Procedures
    Surgery (midline, flank) [Old school] vs Nonsurgical/transcervical
    Speculum procedure (Allen and Wilshire)
    Equipment for nonsurgical (Box Table)
    Day of transfer
    Medications (pre and post)
    Prostaglandin release during transcervical transfer (p4 Graph)
    Technique – details
    The ‘art of transfer’
    15. Factors affecting pregnancy rates
    Age and reproductive status of donor mare
    Embryo age, quality and size
    Transfer technique, technician variability
    Recipient factors
    Expected pregnancy rates (day 16 vs day 50 vs foaling)
    Carry to term data (AQHA data)
    Twins/Triplets from transfer of a single embryo
    16. Pregnancy examination after transfer
    Days of examination (11, 12, 14, 16, 25, etc)
    Relationship between embryo size at transfer and first day visible on ultrasound (graph)
    Percentage of truly pregnant recipients with embryos visible at 11, 12, 14, 16 days (graph)
    17. Disease transmission with embryos
    18. International transport of embryos
    19. Miscellaneous
    Embryo micromanipulation (splitting)
    Embryo sexing
    20. Future directions of equine embryo transfer
    Early pregnancy factor – know when to flush
    Improvement in reproductive management of problem mares (PGE oviduct)
    Assisted reproduction
    Embryo biopsy for genetic diagnosis

    Appendix 1: ET Equipment and supplies
    Fluid types (LRS vs Complete vs old style PBS); osmolarity; pH; stability/shelf life; protein source (FCS, albumen vs PVA) to prevent embryos from sticking; ingredients (general); buffer systems (if any)
    Y tubing
    Filter cups – types (list and photos), how to use them (i.e. fill with fluid as per Fernando Rivera); direct visualization vs pour-off)
    Search dishes (round vs square; size; gridded vs plain)
    Microscopes and micrometer (types of scopes; magnification, glass – clear vs frosted; sources; new vs used)
    Cleaning procedures (what can be re-used); autoclave; enzyme cleaning; gas sterilization)


    Patrick M. McCue, Edward L. Squires

    "... a well-written book. It covers everything involved in equine embryo transfer work from start to finish. The book is written in a manner that will provide valuable information to anyone interested in learning embryo transfer or someone who is already doing some embryo transfer but would like more information. ... I particularly liked the pictures and charts, because they nicely complimented and augmented the text. This book also contains a lot of descriptive statistics for a large number of embryo transfers. It is a good value and will be a nice addition to the library of anyone interested in equine embryo transfer."
    —Shawn Jensen, DVM, Bluff Country Equine, Winona, Minnesota, USA, from Vet Med Today: Book Reviews, JAVMA, Vol 247, No. 6, September 15, 2015