Prebreeding and Infertility Examinations for Mares

A pre-breeding mare examination is a good opportunity to discuss the reproduction process and any questions you may have, as well as checking your mare’s suitability for breeding.

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Pre-breeding mare examinations

This often involves:

  • General physical examination, including mammary gland and vulva
  • Rectal palpation and ultrasound examination (a scan) of the mare’s uterus and ovaries.
  • Vaginal and cervical examination using a speculum.
  • Pre-breeding swabs for diseases including Contagious Equine Metritis (C.E.M.), a contagious venereal disease.
  • Pre-breeding bloods for infectious diseases such as Equine Viral Arteritis (E.V.A.) and Equine Infectious Anaemia (E.I.A.).
  • An endometrial swab to assess the uterine environment.

Equine infertility investigation

“My mare isn’t falling pregnant – what is wrong?”

Unfortunately, getting a mare pregnant is not always plain sailing. This can be for a number of reasons:

  • Mare fertility reduces with age, particularly in mares that have not been bred previously.
  • The stallion is not very fertile (or is not very compatible with an individual mare) – the stallion can also be investigated if necessary.
  • Infection or inflammation within the reproductive system, particularly post-breeding endometritis.

What is involved with a mare fertility investigation?

  • A careful history of the mare will be taken
  • Ultrasound examination of the reproductive tract
  • Vaginal and cervical examination with a speculum
  • Uterine swabs and endometrial cytology/culture
  • Uterine biopsy
  • Endoscopy of the uterus

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Mare Pregnancy Support – Perinatal Care

When should I have my mare scanned for pregnancy?

The first pregnancy scan usually takes place between day 14-16. This early scan is important to recognise if twin pregnancies exist so that swift action can be taken (see below). If the mare is declared not in foal, we will often recommend a second scan a few days later to confirm this. 

If she is confirmed in foal, then a heartbeat check is recommended between day 25-30. This early period is a common time for the mare to lose her pregnancy, but she could still be bred again the same year. This becomes much more difficult after day 40.

Sometimes further scans are undertaken at day 45 and/or day 60 but this is often down to owner choice. 

How long does pregnancy last in the horse?

Gestation is commonly quoted between 340-345 days, ponies are typically slightly longer but anything between 320 and 365 days is considered normal. 

Can horses have twins?

The mare's uterus and placenta has not evolved to support more than one foetus at any one time. It is extremely rare for twin pregnancies to be born alive and healthy. Most commonly abortion will occur from month 5 onwards. In the worst cases twins can lead to difficulties giving birth for the mare and her life could be at risk. For this reason if twins are identified they must be managed by the vet to reduce them to a single pregnancy. If this is done between day 14-17 it is a quick, painless procedure for the mare with minimal risk of damaging the remaining pregnancy.

Can my foal's gender be determined through ultrasound? 

Foetal sexing scans can be performed at certain stages of pregnancy with good accuracy. Whilst this is not a service we currently commercially offer please do contact us if you are interested and we can refer you on to other colleagues. 

Are there any other ways to check whether my mare is pregnant if she cannot be scanned?

Bloods can be tested for hormones associated with pregnancy after day 45 but are more reliable beyond day 65. Bloods do not reveal if twin pregnancies exist, if a heartbeat is present, or give information about the health of the placenta or the ovaries. If bloods are recommended this is usually alongside a scan, if there are queries about unusual findings. It may also be recommended in miniatures where rectal scanning carries a higher risk. 

What preparations do I need to make for foaling?

You will need to decide whether or not you will be foaling the mare yourself or whether you will send her to a professional stud. As the foaling process can start without too much warning and things go wrong quickly it is imperative to have some insurances in place to make sure you will observe the foaling and can take action if required. Foaling alarms (sweat and vulva alarms), milk tests and stable cameras can all be used.

It is a good idea to have a tail bandage, towels, iodine dip for the foals navel and scissors to hand (in case of red bag delivery). The mare should ideally foal in a large straw stable and it is sensible to get her used to the routine of coming in over night around 4 weeks in advance of anticipated foaling date. 

Does my mare need any additional healthcare during pregnancy?

Mares should continue their routine vaccinations and additionally have a Flu/tet booster during the last 6 weeks of gestation to ensure antibodies are present in her colostrum (the first milk she produces which passes on all the antibodies to the foal). 

In addition vaccination to EHV 1 and 4 can be given at months 5, 7 and 9 of pregnancy. 

Worming programmes should continue for the pregnant mare, as long as the label on the wormers says it is safe to use in pregnancy.

Dental checks should continue every 12 or 6 months as recommended by your vet or qualified equine dental technician. Sedation is also very safe for the pregnant mare. 

My mare's behaviour has changed during pregnancy, should I be worried? 

This can happen for better or for worse. Often mares adapt very well to the routine of being a broodmare, living outdoors more and having a more relaxed life. Occasionally mares can become aggressive for periods during pregnancy due to the high level of hormones being produced by the foetus. If you have any other concerns about her behaviour please contact us.

My mare should be in foal but she is showing signs of being in season, is this normal?

Around 10% of mares will show signs of being in season (oestrus) during pregnancy and this is normal for them, but a scan or blood sample is recommended to ensure she has not lost the pregnancy. 

Should I feed my mare more now she is pregnant?

From conception until month 9 the mare can be fed according to her condition and level of exercise, as for any other adult horse. From month 9 she should have additional protein and calorie source, commonly provided by a broodmare and youngstock mix. Any change to feeding should be made slowly over 7 days. 

Post-Birth Mare Support

We recommend a check for all newborn foals and their dams during the first 1 or 2 days of age. During this consultation, a full clinical examination of both the foal and the dam is carried out. This allows us to identify any issues early on, give advice on the care of the newborn and perform a blood test to check the foal has received enough colostrum (the first milk containing antibodies needed by the foal). The placenta will also be checked so please take this out of the stable as soon as possible, hose it off if it is covered in straw and keep it in a bucket away from wildlife/dogs until the vet arrives.

The newborn foal should be standing within one hour of birth, nursing from the mare within two hours and the placenta should be passed within 3 hours. If any of these times are not met please call us for an emergency appointment. 

Once the mare and foal have sufficiently bonded and have been checked over they may be turned out. Usually this is sometime between 12 and 48 hours. 

Your mare should continue to be monitored in case of any post birth complications. If she has colic, develops a fever, goes off her food or is very quiet please call us immediately. Small amounts of dark red vaginal discharge may be normal up to 7 days following the birth. 

The foal is typically weaned around 6 months of age.

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