Problems of late pregnancy

Abdominal wall hernias or prepubic tendon ruptures

In late pregnancy the body wall is occasionally weakened by the combined weight of the foetus plus the membranes and placental fluids to the extent that it can tear. The muscle itself may tear or the prepubic tendon, which attaches them to the front of the pelvis. The signs include an area of oedema (swelling) up to 10-15cm thick extending along the ventral midline in front of the udder. The mare is often uncomfortable; she may show signs of colic and resent the area being touched. The udder may appear to have moved forwards.

The treatment is restricted exercise and non-steroidal anti-inflammatory drugs. A well-padded abdominal support bandage may be applied. Some mares are able to foal unassisted, but the abdominal wall is often too weak to push the foal out. An assisted delivery or caesarean section is likely to be required, so the birth should be supervised. It may be possible to repair the defect surgically, but this can very difficult. Further pregnancy puts the welfare of the mare at risk.

Early lactation (running milk)

Mares that run milk earlier than 2 weeks prior to foaling are classed as at risk. If this is observed a vet should be contacted immediately for further advice.

Premature lactation can be associated with impending abortion or placentitis and so the mare should be checked by the vet who may decide to examine the foal and placenta by ultrasonography. Measuring the combined thickness of the utero-placenta can identify a placentitis.  We can also measure the foals heart rate can determine whether the foal is distressed.

A more common complication of premature lactation is the loss of colostrum, which is vital for passive transfer of antibodies to the foal. During the first 12 hrs of life, the foal will absorb antibodies from the mare’s colostrum, which will provide active immunity against infections as the foal matures. Loss of this colostrum can be severely detrimental to the foal.

What to do if your mare runs milk early:

  • Phone the vet for advice
  • Collect the colostrum in a bucket/container and freeze. This can be defrosted and carefully fed to the foal after birth
  • Make arrangements for alternative colostrum source – the vet will advise
  • After the foal is born, try to ensure adequate colostrum
  • Test the foal at 24 hrs old for IgG – this is a quick and simple blood test that the vet will take at the yard and will determine whether the foal has received enough colostrum

Lack of mammary gland enlargement and lack of milk

Mammary gland development becomes apparent during the last month of gestation, especially in the last 2 weeks. A waxy yellow secretion will develop on the end of the teats 1-4 days before foaling. This is known as ‘waxing up’. Maiden mares may not show mammary development until after foaling. If your mare is 1 week before foaling and has no evidence of any udder development then your vet should be contacted and preparations made for an alternative milk and colostrum supply in case no milk is produced. If the mare has already foaled and has no milk, the vet may give injections of oxytocin, which may stimulate milk let down.


Mastitis is an uncommon condition in a mare. It is characterized by a hard, enlarged, painful and hot udder. The mare may also show hind limb lameness and may have a high temperature, which may make her dull and inappetent.

Treatment includes intramammary and systemic antibiotics, regular milking of the mare’s udder, hot packing the udder and pain killers.

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