Reproduction- Mare

Central West Equine has a strong interest in equine reproduction. Since graduating some 20 years ago Dr David Searle ambition has been to perform advance reproductive procedures at the highest level. David has worked on some of the elite horses in all breeds including Thoroughbreds, Standardbreds, Quarter Horses, Stock Horses, Dressage Horses, Show jumpers, 3 day eventers, Endurance Arabians, Whalers and Show Ponies. David even performed the first successful embryo transfer in a Shire in Australia. David has travelled the world to learn from some of the world’s best reproductive vets. He was invited to attend the International Symposium on Equine Reproduction which is held every 4 years and attended by all the world leaders to exchange the latest research and techniques. With David’s 20 years of experience leading the Central West Equine team, the very latest techniques and equipment are available to assist you with all your horse’s reproductive needs. The services offered by Central West Equine include

  • Routine mare examinations
  • Investigation and treatment of the barren or subfertile mare
  • Set-up for walk on breeding’s
  • Foaling down
  • Chilled Semen insemination
  • Frozen Semen insemination including low dose deep horn insemination
  • Embryo Transfer
  • Embryo freezing
  • Placental scanning
  • Foetal sexing

Routine mare examinations

Ideally mares should be examined at the start of each breeding season prior to being sent to the stallion. This will help identify any conditions that may be detrimental to her chances of conceiving and carrying a foal to term. At a minimum a thorough physical examination of the mares external genitalia along with a manual and ultrasound examination of her internal genitalia should be performed. This gives a good overall view of her reproductive tract and helps in identifying any likely issues that may cause concern. It also allows you to determine at what stage the mare is at in her cycle. Depending on where the mare is at in her cycle various treatments can be given to alter her cycle to allow optimum breeding. Depending on the mare and stallion situation further tests such as uterine or clitoral swabs can be taken. Once the mare has been served or inseminated ideally she should be examined at Day 15, 28 and 45 of gestation. Examination at Day 15 allows for early pregnancy detection prior to her next cycle and is also the ideal time for manual twin reduction. It also allows early detection any issues which may affect implantation of the conceptus. It is also the ideal time to correct any external confirmation issues such as poor vulval conformation with a Caslick’s procedure. Examination at Day 28 detects a foetal heart beat and allows confirmation of pregnancy. Generally a final pregnancy examination is performed at 45 days of gestation, this is when a pregnancy certificate is issued. At this stage the foetus has started producing its own progesterone and is generally considered a safe time to transport the mares longer distances. Central West Equine has all the facilities and equipment to perform these examinations. Depending on the findings and the history of the mare the timing of the examinations may change and various treatments maybe given to help with the successful breeding of your mare.

Please contact us to discuss any concerns you have regarding the breeding of your mare.

Routine mare examination

Figure 1 David performing a routine examination of a mare prior to breeding.

Figure 2 Twin pregnancies at 14 days on ultrasound one pregnancy will be manually reduced.

Investigation and treatment of the barren or subfertile mare

Unfortunately not all mares are easy breeders. Often their genetic value means that leaving these mares barren is not a desired result and therefore investigation and treatment of these mares is extremely important. The history of these mares is extremely important and can alone give a good indication of the cause or causes of infertility. A thorough breeding examination should then be performed to help narrow down the cause. Once a good history is taken and breeding examination performed further examinations can be performed, the order of these tests will be determined by there likelihood of identifying the cause of the infertility. Further tests which can be performed include endoscopic examination, low volume uterine lavage and culture, uterine biopsies, uterine or clitoral cultures, hormonal assays etc. At the conclusion of some or all of these tests a treatment plan can be determined. Central West Equine can offer the full range of diagnostics tests, we may also recommend that the mare chances of carrying a foal to term is extremely low and that it is better she enters our embryo transfer program as an embryo donor to maximise her chances of successfully breeding.

reproduction in mares

Figure 3 Uterine biopsy forceps

Figure 4 Endoscopic view of adhesions in a uterus

Figure 5 Uterine biopsies under the microscope showing various degrees of change- the degree of change has a good correlation with fertility

Set-up for Walk on breeding’s

Numerous reasons may dictate the fact that a “walk on service” is the better scenario. Some of these reasons may include- sick or valuable foal, lack of agistment or expertise at the stallion end, economics of agistment at the stallion centre, valuable mare with special requirements, competition mare in work etc. With vast experience sending mares for service especially with all the major Thoroughbred Studs in the Hunter Valley and Victoria, Central West Equine can assist in setting up your mare for service to maximise your success rate. We can carry out all the studs’ requirements for swabbing and vaccination protocols and even assist in booking the desired service time. If you want to keep your mare locally please contact us to arrange an initial examination.


Foaling down

Central West Equine offers foaling down for your mare. Having a veterinarian living on the property with flood lit paddocks that are fully fenced with foal netting we are able to offer an ideal situation to foal down your mare. We understand how much time, effort and expense goes into getting your mare to term so why not let Central West Equine care for the birth at what can be a stressful time.

Foaling Down

Figure 6 Foaling down

Chilled Semen insemination

Insemination using chilled semen offers the advantage of being able to access stallion genetics from Australia and New Zealand with a success rate similar if not better then natural service. Central West Equine is perfectly located to be able to offer this service by being located only 10 mins from the township of Orange and only 5 mins from the large regional airport of Orange meaning transport of semen is made easy. Using chilled semen not only allows access to a large semen pool but also means that mares don’t have to travel large distances to stallions especially with foal at foot. There are also savings in agistment and let’s face it nobody looks after your mare and foal as well as you do. Mares for chilled semen insemination are examined frequently to assess the stage of oestrous and when is the right time to order semen. Central West Equine will deal with the stallion owner and organise collection and delivery. All semen is evaluated on arrival prior to insemination. The mare is then followed post insemination to check for ovulation and post service inflammation (uterine fluid), which is the major cause of infertility in the mare. Chilled Semen insemination is offered at a set fee per cycle so please feel free to contact us to discuss breeding your mare.

chilled semen

Figure 7 Chilled semen is transported in a container like this generally as airfreight and the equipment used for insemination

Frozen Semen insemination including low dose deep horn insemination

Insemination with frozen semen allows the selection of stallion genetics from a worldwide pool and even allows the use of stallions which are dead or now infertile. While the success rate is slightly lower than chilled or natural service the ability to access a huge stallion pool far outweighs this decrease. The other huge advantage of frozen semen is that it stores in liquid nitrogen for many years and is therefore available at any time of day or night. There is no need to worry about stallions not collecting, couriers losing shipments or mares ovulating on long weekends. The mares are therefore inseminated at the perfect time for them. Similar to chilled semen mares are examined in early oestrous to determine the stage of cycle and the right timing for insemination. The mares are treated with an ovulatory drug and once close to insemination the mares are examined hourly to make sure insemination is at the ideal time. Insemination is done using the latest equipment and techniques and the semen is placed deep in the uterine horn adjacent to the opening of the fallopian tube. This insemination technique allows the use of low doses of semen with similar success rates. There is an increased degree of post service inflammation (uterine fluid) with frozen semen and this is monitored and treated aggressively as it is the major cause of failure to conceive using frozen semen. We offer set fee insemination using frozen semen and this includes all ultrasound examinations and commonly used drugs. Central West Equine offers very safe facilities for your mare and foal including fully lined foal crush and rubber floor along with a veterinary team with vast experience in using frozen semen so please feel free to contact us with any questions regarding this procedure.


Figure 8 Stallion semen stored in liquid nitrogen at -196 degrees and the flexible insemination pipette which allows the semen to be deposited deep within the uterus.

Embryo Transfer

Embryo transfer gives mare owners huge advantages when it comes to breeding. Some but not all of these advantages include multiple foals per year, mares able to remain in competition while still producing sometimes multiple foals, breeding mares which for multiple reasons cannot carry a foal to term and allowing valuable mares to have foals without putting them through the risk of foaling. Embryo transfer is basically a 3 stage procedure. Firstly the mares are bred normally with either natural cover, chilled or frozen semen with particular attention to the ovulation time as this determines the timing of embryo retrieval. The second part is the embryo retrieval. This is performed generally about 7-9 days post ovulation and several factors play a role in determining when this is done such as age of mare and stallion, type of semen used, time of year, uterine health and previous history. Embryo retrieval involves lavaging the uterus with fluid and filtering the fluid for the presence of an embryo under a dissection microscope. The procedure is performed numerous times until either an embryo is found or the uterus has been thoroughly lavaged. The third part is the embryo implantation, once an embryo is obtained it is cleaned in buffered holding medium specifically designed for equine embryos and held in this medium while a recipient mare is prepared. Central West Equine has a large herd of hand chosen recipient mares which are generally young standardbred or stockhorse mares which are of good nature, vaccinated and well cared for. These mares are examined frequently to monitor their cycle as it is imperative their cycle lines up with that of the donor. Once chosen the recipient has a thorough iodine clean and the embryo is implanted transvaginally. The mare is then pregnancy tested 7 days after implantation. Central West Equine offers set fees for all the stages of embryo transfer. Please feel free to contact us with any questions regarding the procedure or the recipients that are used.


Figure 9 Grade 1 Day 8 Blastocyst- perfect for transfer

Embryo Freezing

Embryo freezing takes all the advantages of embryo transfer and adds a few more. Added advantages of freezing include being able to collect embryos from mares out of competition and store them for a prolonged period while implanting at the desired time (earlier foals), the ability to store a mare genetics as a form of insurance policy, sell mare genetics more easily and allow easier transportation within Australia. Embryo freezing is very similar to embryo transfer except that the embryo once collected is frozen using the latest vitrification techniques and stored in liquid nitrogen for an indefinite period of time. Timing is the critical issue with embryo freezing and it is important to know the ovulation time within a few hours as embryos at a morula stage (Day 6 ½-7) freeze much more successfully than a blastocyst (Day 7-8). Once the embryo is stored it can be defrosted and implanted into a timed recipient at any stage. The huge advantages of embryo transfer have already been mentioned above. Embryo freezing is a very successful procedure that has been performed in cattle for over 40 years and is now being used in horses. If you have any questions regarding embryo freezing and the suitability of your mare for the procedure please feel free to contact Central West Equine.


Figure 10 Day 6 1/2 Morula perfect for Vitrification

Placental scanning

Placentitis is a significant cause of pregnancy loss in mares and also a major cause of foals born prematurely “red-bag”, sick and/or poorly developed due to septicaemia and lack of nutrient associated with infections of the placenta. Placentitis is inflammation of the placenta generally caused by either a bacterial or fungal infection. There are 2 general types of placentitis- 1/ Localised- this is normally seen around the cervix and is caused by infection through the cervix, this is often associated with poor confirmation, previous cervical damage and increasing age. 2/ Generalised or focal placentitis not involving the cervical region – this is seen with systemic infections and is the type of placentitis which is seen with Equine amnionitis and foetal loss syndrome (EAFL) associated with ingestion of parts of the Processional Caterpillar.

The external signs of placentitis are generally early udder development “bagging-up” and or a purulent abnormal vaginal discharge. Unfortunately once these external signs have developed the placentitis is generally quite severe and the prognosis for treatment guarded. However ultrasound examination allows much earlier detection of placentitis and therefore earlier treatment which is associated with a much better prognosis. Placental scanning can be performed as early as 3 months of gestation and the interval between scans varies depending of various factors. Mares are generally graded as to their risk of placentitis using numerous factors including age, number of foals, history of placentitis in previous pregnancies, septic or poorly developed foals, abortion, previous difficult foaling’s and conformation. Once a mares risk has been determined a placentitis scanning program can be devised.

Treatment of placentitis involves resolving any infection with the use of antibiotics or anti-fungals, reducing inflammation using NSAID’s and maintaining cervical competency using Altrenogest.

Dr David Searle of Central West Equine has a vast experience in treating placentitis in mares so please feel free to contact the clinic to discuss options and timing of examinations for your mare.

Figure 11 Transrectal examination of the Combined utero-placental thickness

Figure 12 Transrectal examination of the cervix

Foetal Sexing

Determining the sex of the foal prior to birth has numerous advantages for mare owners including being able to sell older offspring, selling mares in foal with a known gender often bringing more money, continued breeding of an embryo donor if a specific sex is required. Gender determination can be performed at 2 different stages in the mare. The first time is between 65-70 days and the second stage is greater than 120 days. When performed after 120 days the accuracy is increased as more structures can be identified. Central West Equine understands the huge advantages in sex determination and has an ultrasound machine with a dedicated probe to allow this procedure.

Figure 13 David determining the sex of a foal using a dedicated ultrasound probe