Equine Reproduction: Getting Your Mare In Foal

By. Dr Cecilia Cortina Di Favria,

Mare and foal 6-2

What do I do if I want to breed my mare?

Making a good plan is essential for a positive outcome. We can help you with this. First, decide whether your mare needs to go away to the stallion or breeding farm or whether you can keep her at home for breeding. This will depend on whether you are breeding her naturally or with artificial insemination; using cooled or frozen semen, and her previous reproductive history. Another factor in this decision is the stallion you would like to use, his fertility and what type of semen is available.

Why do I need to get my mare examined by a vet?

It is vital to make sure your mare is a good candidate to breed, with a normal and healthy reproductive tract. Knowledge of where the mare is in her estrous cycle and following her while in heat will increase her reproductive efficiency. Fertility declines with age, so horses over 10 years of age who have not had a foal previously or mares that have had many foals, may find it more difficult to conceive. It is also important to check for inflammation and infectious and sexually transmitted diseases. Whether you are having your mare bred naturally or via artificial insemination, it is important to time the breeding accurately, close to ovulation, in order to increase the chances of conception and decrease the costs involved.

What does a pre-breeding examination include?

  • Clinical exam: it is important to check that the mare is in good clinical health.
  • Vulvar exam: vulvar conformation is one of the barriers that prevent and protect the uterus from contamination from air and/or faeces
  • Vaginal exam: it is essential to evaluate the cervix and make sure it has a good seal. If it doesn’t close properly it allows contamination of the uterus, potentially leading to chronic infection and inflammation
  • Rectal exam and ultrasound: rectal palpation and ultrasound allows the ovaries, uterus and cervix to be evaluated anatomically and functionally
  • Clitoral swab, Uterine swab and cytology and Uterine biopsy: these allows abnormalities to be identified at the beginning of the breeding season and addressed before breeding your mare

How should my mare be prepared for breeding?

Good general health! Yearly vaccination and don’t forget the Hendra vaccine as well ; Dental health,  de-worming and body weight are all essentials to a good health of the mare and of course for the foal!! Make sure your mare finishes the winter in lean to good body condition. Overweight mares have reduced fertility. Most mares stop cycling in the winter months and begin cycling in spring in response to the longer day length. Breeding an early foal can be more difficult as mares may not have started to cycle regularly. There are different methods to hasten the first ovulation of the season, which our vets can discuss with you. Some mares will benefit from being rugged, put under lights, or the use of an Equilume mask to assist them to start cycling. Don’t forget, this season we can offer also Traditional Chinese Medicine consultation with acupuncture!

When do I find out if my mare is pregnant?

Gestational length is incredibly variable in the mare ranging, on average, from 320-340 days.

Most veterinarians recommend the first ultrasound examination at 14 or 15 days post-ovulation, when embryos are still able to move within the uterus. This allows identification and resolution of twin pregnancies if they are present. It is then recommended to have your mare examined again between day 28-30 and day 42-45 to check for a heartbeat and to assess fetal viability. Unfortunately, if the mare loses the pregnancy after day 40 it is highly unlikely that she will cycle again normally and therefore will not be able to be bred again that season.  Fetal sex determination can be performed between 58-70 and 110-120 days if desired. 

Here at Newcastle Equine Centre, we offer all services mentioned above to ensure a positive breeding experience for you, your mare and her foal. To schedule a consultation or for more information, have a chat to one of our vets by calling (02) 4927 6135.