Mares that deliver foals with the hind end first are more likely to do so again, according to researchers.
Foals are normally born head and front feet first, known as anterior or cranial presentation.
Posterior presentation – being born hind end first – is not only rare, probably accounting for less than 0.2 percent of all births, it is bad news. It often results in death of the foal, which may either be born dead, or die soon afterwards.
Having advance warning of a posterior presentation birth may allow early intervention to minimise problems.
The latest issue of Equine Science Update, reporting on the latest research in the area, said it was possible to identify the orientation of the foetus on ultrasound scan, but it appeared that another indication that a mare was at high risk of having a posterior presentation foaling was the knowledge that she had done so before.
Writing in the Veterinary Record, John Newcombe and Gary Kelly reported five instances of posterior presentation in consecutive pregnancies in two mares – one a thoroughbred, the other a gypsy cob.
As posterior presentation is generally very uncommon, they conclude that once a mare has given birth to a foal hind legs first, she is likely to do so again at the next foaling.
They point out that posterior presentation of the foal frequently results in death of the foal at birth or shortly afterwards, even in the absence of an obstructed labour, which is known as dystocia.
They advise that any mare known to have foaled posteriorly in the past should be considered at risk of doing so again, and should be monitored closely as she gets near foaling.
They suggest that measures such as elective caesarean section might be considered since the birthing process is likely to result in an obstructed labour and possible death of the foal due to fluid inhalation, limb malposition or rib fracture.
Five cases of consecutive posterior (caudal) presentation of the fetus in two mares.
Newcombe JR, Kelly GM.
Veterinary Record (2014) 175, 120
The abstract of the study can be read here.