Dystocia - Cattle
Introduction
Dystocia refers to abnormal or difficult birth.
It is expected to occur in about 10-15% of first-calf heifers and in 3-5% of mature cattle.
In cattle the most common cause is foeto-maternal disproportion, but faulty disposition is also often to blame.
Early intervention minimises the effects of dystocia on calves. Cows, and especially heifers should be monitored regularly and provided with assistance promptly if stage 2 labour is prolonged, ie more than an hour.
Clinical Approach
A thorough history should establish the length of gestation, parity, and problems seen during pregnancy. Also find out when the animal started straining and if any water or fluid bags have appeared.
It is also important to establish what has been done so far by the farmer including any drugs administered.
Physical examination of the dam who might have systemic illness, such as milk fever. Proper restraint and assistance should be sought, and initial treatment may include fluid therapy, pain relief and the provision of calcium.
Position of the dam: cows should be standing.
Vaginal examination: the vulva, vagina and cervix should be assessed for dilation, torsion or injury. Copious lubrication should be used at all stages of the examination.
Foetal assessment should establish its presentation, posture and position and identify any palpable structures. Foetal viability can be assessed by feeling pulses on the limbs or tongue.
Anaesthesia is not essential, but an epidural can be administered to help reduce straining.
Manual correction of dystocia: relies on traction to facilitate expulsion, repulsion of the foetus back into the uterine lumen to enable further manipulation, and extension of the foetal extremities.
Ropes can be applied to both legs and the head and traction applied whilst manually dilating the vagina and vulva.
If the foetus is too large to be delivered vaginally, a caesarean operation or a foetotomy should be performed.
Prevention
Foetomaternal disproportion is one of the major contributors to dystocia, and this can be prevented with proper reproductive management.
Replacement Heifer Development
Nutrition should be maintained in heifers to allow modest rates of gain over the pregnancy period. Restricting food in the late stages of pregnancy does not prevent a large calf and leads to a weak labour and increased dystocia rates.
Heifer pelvis assessment can be carried out to select replacements for the herd. Those heifers with a small pelvic area before the breeding season may then be culled or selectively mated to easy calving bulls, and those with a small pelvic area at the time of pregnancy examination may be aborted, culled, or identified for careful observation at calving. Some evidence suggests that culling heifers with the narrowest pelvic width may be more effective than culling based on pelvic area.
It is important to ensure heifers are well-grown and calve down at 2 years of age at the earliest.
Sire Selection
Sires can be selected for ease of calving and estimated birth weights. Many non-genetic factors influence birth weight, such as age of the dam and environment, and so genetic selection is not a fool-proof method of avoiding dystocia.
Early Intervetion
Not all dystocia can be prevented, such as malpresentations, and early intervention is paramount in ensuring a live birth.
Farm workers need to be trained to deal with a dystocia and recognise when further help is needed. A delay in assisting may mean the loss of the calf or injury and even death of the cow. However, it is important to allow sufficient time for the dam to dilate before applying traction.
Post-partum Complications
Dystocia leads to an increased risk of post-partum complications in cattle, such as:
Retained placenta: usually treated by manual removal or oxytocin.
Metritis: which can lead to toxaemia and laminitis and should be treated aggressively.
Cervical tears
Uterine rupture
Uterine Haemorrhage
Perineal lacerations
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References
Kahn, C. (2005) The Merck Veterinary Manual 9th Edition Merck and Co
Frame, N. (2006) Management of dystocia in cattle In Practice 28:470-476