Dystocia

Introduction

Dystocia refers to abnormal or difficult birth. Causes include maternal factors such as uterine inertia and inadequate size of the birth canal and/or foetal factors such as foetal oversize or abnormal orientation.

Other factors influencing dystocia include: breed, age, parity, body condition, environment, nutritional status and energy balance. Parturition is divided into three stages.

Incidence of Dystocia

Figure of incidence are often unreliable as the assessment of dystocia is highly subjective.

Average figures are:

Cow: 3-4% in dairy cows, much higher in some beef breeds

Mare: 1-2% of ponies, up to 10% in some draught breeds

Ewe: 2-3%, can reach 30% in some flocks

Sow: <1%

Bitch: Can be 100% in some brachycephalic/achondroplastic breeds

Queen: Low in feral animals, high in brachycephalics

Common Causes

Maternal factors tend to be more important in polycotous species, and foetal factors tend to be more important in monocotous species.

Cow: foetomaternal disproportion is common in heifers and beef breeds. Faulty disposition is also important

Mare: faulty disposition, especially postural abnormalities. Foetomaternal disproportion is rare.

Ewe: faulty disposition and twin presentations are the most frequent but are readily dealt with by the shepherd. Foetomaternal disproportion and ring womb are also common.

Sow: uterine inertia, foetomaternal disproportion in gilts and simultaneous presentations occur rarely.

Bitch: uterine inertia, foetomaternal disproportion, especially in brachycephalic breeds as well as other breeds with small litters.

Queen: similar to the dog, foetomaternal disproportion is more common with smaller litters.

Postpartum Complications

Dystocia leads to an increased incidence of stillbirths, foetal rejection by the dam, increased neonatal mortality and morbidity, increased incidence of mortality in the dam, reduced dam productivity and fertility, increased incidence of sterility, puerperal disease and culling.