Equine artificial insemination is now much more common than natural cover for most breeds other than Thoroughbreds (natural cover is still a requirement for the Thoroughbred industry).

This is because:

• You have access to a far wider range of stallions including those abroad (or even deceased stallions if using frozen semen)
• It reduces the risk of injury to the stallion and your mare
• Your mare can be kept locally so you can avoid her travelling her long distances

Equine AI Options

Artificial insemination (A.I.) can be performed with fresh, chilled or frozen semen, and contraception rates are usually good. To achieve good contraception rates, the mare’s oestrus cycle needs to be monitored carefully. This identifies exactly when to inseminate her (as close to ovulation as possible) to achieve the best results. The mare may also be given hormones to manipulate the cycle to improve success rates. 

Where does the artificial insemination of the horse take place?

With chilled semen it can be done on client premises, with frozen it is only at RVC due to health and safety around the semen being stored at -196 degrees in liquid nitrogen and in addition the frequency of ultrasound examinations needing to be performed on the mare prior to insemination

What happens after my mare has been artificially inseminated?:

After insemination, your mare will be re-scanned to check for ovulation and any post-breeding problems such as uterine inflammation or fluid. If problems are encountered, post-breeding treatment may be required (e.g. a uterine flush). Scanning for pregnancy (and specifically to check for twins) is then typically performed at day 14-16 post ovulation, and then again at day 28-30 to check for a heartbeat. A 45-day pregnancy scan is also usually performed to make sure everything appears to be progressing normally.

Fresh or chilled semen for equine AI

Ideally, the mare will be inseminated with fresh or chilled semen in the 24 hours prior to ovulation (although many stallions will have semen which will survive for longer than this). This timing, achieved by regular ultrasound scanning of the mare’s uterus, achieves conception rates of around 60%. Older mares or those prone to endometritis are better suited to fresh/chilled semen than frozen.

Good communication with the stallion owner/stud is imperative so:

• Check which days they can collect and send the semen (often dictated by the post or courier service).
• Ask the stallion owner if the stallion’s semen chills and travels well.
• Check if there are transport costs.

N.B. Semen coming from abroad must be accompanied by the relevant health certification

Frozen semen for Equine AI

Frozen semen can be kept for years and is thawed immediately prior to insemination. It has a shorter life span once thawed than chilled semen and so careful monitoring of the mare’s cycle is required to time insemination much closer to ovulation, achieving conception rates of around 50%. This requires several ultrasound examinations, up to every six hours. Due to the frequency of scans required, including overnight, and the specialised storage of the semen in liquid nitrogen, your mare will need to stay with us for a minimum of 2 nights.

Benefits of using frozen equine semen for AI

• Using stallions from all over the world.
• Using deceased stallions with previously collected semen.
• Using stallions which are still out competing, and not retired to stud yet.

Guidance and tips for stallion selection for AI using frozen semen

• Buy from a reputable stud.
• Ask them about the semen quality and how well that particular stallion’s semen freezes and thaws. How good is the semen motility after thawing?
• Ask how many doses/straws of the semen are included in the price.

How planning logistics can help your chances of repro success

Specialist transport of frozen semen is required. The semen should arrive at our hospital before your mare comes into season so we are ready to go. It will be stored by us in our liquid nitrogen unit. Please ask us about these transport costs.

Semen from abroad must be accompanied by the correct health certification/paperwork or it will not be inseminated. This is enforced by DEFRA

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