Causes of Dystocia
Causes of Dystocia include maternal factors like weak uterine contractions, a narrow birth canal, or hormonal imbalances, as well as fetal factors such as oversized fetuses, abnormal positioning, or congenital defects.
The causes of dystocia may be divided into the following categories:
- Hereditary causes
- Nutritional and management causes
- Infectious causes
- Traumatic causes
- Miscellaneous causes
1. Hereditary Causes
The heritable causes of dystocia include genetic defects in the dam that predispose her to birthing difficulties, as well as hidden or recessive genes in the parents that may result in fetal abnormalities, increasing the risk of dystocia.
Those hereditary defects in the dam predisposing to dystocia are:
- Inguinal hernia
- Persistence of the mullerian duct with a large band
- Uterus didelphys
- Uterus unicornis
- Twinning
The hidden and usually recessive genes in both male and female animals may produce a variety of pathological condition affecting the fetus or fetal membranes, thus causing dystocia. Eg: hydramnios, hydrocephalus, prolonged gestation due to autosomal recessive gene, muscular hypertrophy or double muscling.
2. Nutritional and Management Causes
- Animals that are stunted frequently develop dystocia at parturition. This stunted development may be due to poor nutrition or chronic diseases.
- Growth and development in young animals should proceed normally from birth to puberty, from puberty to conception, and during the gestation period for parturition to be physiological.
- High feeding levels may favor dystocia, especially in heifers, due to excessive fat deposition in the pelvic region, which predisposes them to difficult parturition.
- Severe vitamin A deficiency may increase the risk of uterine infections and fetal death.
- Neglect during the approach or onset of parturition may contribute to dystocia.
- Breeding too soon after parturition, lack of exercise, and close confinement can also lead to dystocia.
3. Infectious Causes
All known infectious diseases, such as brucellosis, leptospirosis, vibriosis, salmonellosis, viral infections, and other septicemic or infectious diseases, should be controlled to minimize late abortions and premature births, where dystocia is commonly observed.
4. Traumatic Causes
Ventral hernia and rupture of the prepubic tendon late in gestation may occur due to traumatic causes.
Torsion of the uterus can result from sudden slipping, falling, or rolling during advanced pregnancy.
Pelvic fractures with secondary deformities and exostoses are most commonly seen in small animals struck by motor vehicles. These injuries may lead to stenosis of the birth passage, resulting in severe dystocia.
5. Miscellaneous Causes
The causes of posterior and transverse presentations are not well understood. In polytocous animals, a smaller litter size often leads to larger fetal weight, increasing the risk of dystocia.
An imbalance of hormones such as estrogen, progesterone, or relaxin, along with the failure of uterine muscles to respond to oxytocin or a disruption in oxytocin release, may delay the first or second stage of parturition, leading to uterine inertia.
The immediate causes of dystocia are divided into:
- The maternal causes
- Fetal causes
