Backwards Foalings

– reverse presentations of the foal – are rare but present particular difficulty. Potential for repetition is also present

By Professor John Newcombe, BVetMed, MRCVS

Backwards foalings – reverse presentations of the foal – are rare but present particular difficulty. Potential for repetition is also present.

Lay abstract

Backwards Foalings - normal presentation

In posterior (backwards) or caudal presentation, the foal is in a longitudinal alignment with the posterior end presented to the birth canal. At birth, either the feet, the hocks or the rump and tail may first appear at the vulva or be present just inside the vagina. This presentation is essentially different from that described as posterior presentation in the human where the head is presented but rotated 180 degrees.  Although uncommon [1, 2] delivery of a posterior presentation is rarely straightforward. Rump or breech presentation due to bilateral hip flexion occurs in 50% of cases [2] and results in the most serious from of dystocia. The second stage of labour may proceed without any part of the foetus appearing at the vulva. Unless both hind limbs can be extended by manipulation, then caesarean section is the only alternative to euthanasia of the mare. Hock presentation (25%) [2] may be reduced to a more normal feet first delivery but even in this presentation, delivery may have to be assisted. Presentation is more normally two ‘upside-down legs and no head. Vaginal investigation easily finds a tail, but in the absence of a tail, it could be an upside-down anterior presentation with a completely reflexed head and neck (also unlikely). Unless the foal is small, delivery of the ribcage causes a relative oversize. During an anterior delivery, as the thorax enters the pelvic canal, it can be compressed as in a forced expiration. However, during posterior delivery, the ribcage becomes expanded since the last ribs become impacted at the entrance to the pelvic canal. Even a successful delivery frequently still results in bilateral cracked ribs (personal observations). Any prolongation of this phase may result in asphyxiation of the foal due to compression of the umbilical cord. Thus, knowledge of an impending posterior presentation may help to prevent a serious or even fatal dystocia. Possibly fatal to both mare and foal

Backwards Foalings - Posterior PresentationThe clinical notes made at 577 pregnancy diagnoses of foetal orientation from 40 days to term were reviewed. The incidence of anterior orientation (AO) increased from 60 days to term. Incidence of posterior orientation (PO) decreased from 130 days to term.  When the foetus was in anterior presentation at birth, PO was not seen after 200 days. Incidence of transverse orientation (TO) was most frequent at around 120-150 days and almost zero after 200 days. TO appears to be a transitional phase between PO and final permanent AO. The reasons why AO is increasingly present from as early as 60 days is interesting. As speculated in a previous communication on posterior presentation [1], the foetus seems to ‘prefer’ the AO because although it is lying on its back in later gestation, its head is always higher than its abdomen if not its chest. Indeed, its rump and tail would lie ventrally in the mares abdomen while its head is near/in the pelvis. Perhaps the organs of balance are sufficiently developed to appreciate this?

Backwards Foalings - Breech DeliveryThere is good evidence that PP at birth is more likely to be repeated in an individual mare [1]. Mares known to have had a previous posterior presentation should be examined after 160 days and in high-risk mares, the final examination, no earlier than 200 days. Caesarian section should be considered to avoid dystocia in confirmed posterior presentations. With this knowledge, all mares known to have had a previous PP, should be examined no earlier than about 200 days to determine the presentation.


1: Newcombe JR and Kelly GMM (2014). Five cases of posterior (caudal) presentation of the foetus in two mares. Veterinary Record 215:120. Doi: 10.1136/vr.101532
2: Vanderplassche M.(1993) In Equine Reproduction. McKinnon and Voss, Lea and Febiger Philadelphia p 578-587

© 2023 Professor J.R. Newcombe
Illustrations © 2001 Kathy St. Martin