Umbilical Cord Torsion

Introduction

In mares, the umbilical cord is normally twisted, usually in a clockwise spiral. The normal length varies from 36-83cm.

Increased cord length (>80cm) has been associated with excessive cord torsion which can cause twisting of the umbilical blood vessels. This twisting causes increased resistance to blood flow in both directions and poor placental perfusion leads to foetal death and abortion of the autolysed foetus.

This represents the commonest non-infectious cause of equine abortion.

Clinical features

The aborted foetus may be autolysed due to foetal death and a period of time before abortion occurs.

The amniotic part of the umbilical cord is very long and very twisted and the cord shows local swelling and discolouration.

The foetal abdomen may be dilated due to serosal effusion.

Diagnosis

Diagnosis is made on examination of the foetus and an excessive twisting of the cord.

Histological examination of the peripheral regions of the allantochorion may show microthrombi in stromal vessels, and necrosis and calcification in many villus cores.

Prevention

This cause of abortion cannot be prevented, but it only constitutes approximately 1% of abortions in mares. Torsion of the cord is often blamed for abortion if no other cause can be found, and the actual incidence may actually be lower.