1 Dec 2016
Difficult calvings are common events for farm animal vets and are rarely straightforward. However, as Paul Wood explains, they can be a good way for new vets to gain clients’ respect.
Paul Wood
Job Title
The term dystocia describes any abnormal or difficult birth in any species.
In cattle, it is more likely to occur in heifers (10-15%) than older cattle (3-5%), but this can be slightly higher in beef breeds.
Numerous factors can increase the likelihood of dystocia, including breed selection, condition of the dam and concurrent disease status.
The most common cause of dystocia in cattle is fetomaternal disproportion; however, abnormal calf presentations, postures and positions are also seen frequently.
It is not always possible to predict when dystocia will occur, but the experience of the farmer may identify potential problems sooner.
Early, skilled intervention is essential for the best outcomes for both cow and calf.
However, inappropriate interventions can lead to poorer outcomes, such as damaging effects on the long-term reproductive performance of the dam.
It is important to be able to identify when parturition is abnormal, and careful questioning of the farmer to discover what has been happening with the cow over what time period can often be a way to do this.
Table 1 shows a rough time schedule for the three stages of parturition and what should be occurring during these times.
It is important to not just rely on times as an indicator of problems with parturition. The progression of the calving and demeanour of the dam should also be considered.
If no positive progression in the parturition has occurred in one to two hours, potential problems should be investigated. It may take first-time heifers longer to progress, so close monitoring is essential to ensure problems aren’t arising.
Once you are called to assist a calving, it is important, on arrival, to assess the dam to discover the reasons for the dystocia. You should establish a thorough history from the farmer, including gestation length, parity and any recent problems the cow has had.
The farmer should also be asked about what the cow has been doing prior to your arrival – when straining started, whether the water bag has been observed and any interventions the farmer has made.
A physical examination may reveal signs of a systemic illness – for example, hypocalcaemia – that may be causing the problem. If the dam is recumbent, making her stand, if able to, will make examining the reproductive tract and any manipulations or traction easier.
The use of epidural anaesthesia may help prevent straining during examination and repulsion/repositioning of the calf.
The reproductive tract should be assessed for dilation, injury or possible torsions. It is important to ensure you and the external area of the cow is as clean as possible and plenty of obstetrical lubricant is used throughout the procedure.
Although bacterial infection of the reproductive tract is common following calving, we should aim to minimise contamination as much as we can.
The calf can be assessed to identify its presentation, posture and position (Figures 1a and 1b). The identification of multiple calves is also important. Fetal viability can be assessed by withdrawal responses (legs, head and tongue) or anal tone. Pulses can sometimes be felt.
Many possible causes of dystocia are seen. Figure 2 describes most of these and whether the inherent problem is with the dam, calf or both.
Once the cause of dystocia has been identified, a suitable treatment or intervention plan can be decided with the farmer. Some farmers may see more value in the cow or calf and this may lead them to preferring certain interventions.
In this article, the author discusses three types of intervention. These and more will be discussed in more detail during the presentation at LVS.
Once the presentation, posture and position of the calf/calves have been identified, attempts can be made to correct any malposition.
Repulsion of the fetus into the uterine lumen may enable easier corrections and extensions of limbs. If the cow is straining and epidural anaesthesia has not yet been administered, this should be done before any manipulations are attempted.
Copious amounts of obstetrical lube should be introduced; if necessary, large volumes can be pumped into the uterus, past the calf, using a drench pump.
When manipulating the calf and its extremities, it is important to protect the uterine wall from damage. The main parts of the calf that may damage the tissues are the hooves and teeth – these areas should be cupped in the hand whenever possible during attempts at manipulation.
Various tools and equipment can aid the manipulation of the calf, such as calving ropes, chains, rope introducers, obstetrical hooks and the gyn-stick (Figure 3).
Once the calf is positioned appropriately, traction can be applied to achieve expulsion. It is important an appropriate amount of traction is used and you are able to ensure no problems are developing while traction is applied.
The author prefers to keep his hand per vaginum around the calf to continually manipulate the soft tissues and identify any potential fetomaternal disproportion not originally identified.
In this situation, it is important to work closely with the farmer so traction is applied only when you tell him or her. If possible, this should be at the same time the cow shows any signs of straining.
Once the rib cage has been delivered, the calf can be rotated by 90° to make delivery of the hips easier. The shape of the cow’s pelvis will permit easier passage of the calf’s pelvis at this angle. It is important excessive force is not used when delivering a calf as this may lead to damage to both dam and calf.
If indicated, a caesarean may be the preferred method of delivering the calf. Indications could be fetomaternal disproportion, fetal monsters, failure of soft tissues to dilate, uterine inertia or even farmer preference.
The approach to a caesarean section should be the same as the approach to any surgical procedure. Surgical field and surgeon cleanliness are vital, as is the experience of the surgeon to perform the procedure.
Numerous approaches and techniques, beyond the scope of this article, are involved in a cow caesarean, but various steps do need consideration.
For one, pain relief, in the form of NSAIDs, should be administered before surgery and, if antibiosis is indicated, should be given to ensure maximum tissue concentrations as close to the start of surgery as possible.
If an epidural has not been administered, this should be done before surgery. Reducing straining will lower the chance of the rumen protruding into the surgical site.
Sedation can be used, but this will affect the calf following placental transfer of the drug. Local anaesthesia should be administered and checked for effectiveness before the incision.
If line or inverted L block methods are used, the site should be clipped and cleaned before administration and cleaned again after.
If possible, the uterus should be manipulated to the incision site and an appendage of the calf locked into the incision. The uterus can then be incised with reduced risk of fetal fluids entering the abdominal cavity.
Once the calf is removed, check for the presence of a second calf. Fetal membranes can be removed if they come away easily, or debulked with scissors to make uterine closure easier. The uterus should be closed with an inverting pattern providing a watertight seal.
No suture material should be present on the surface of the uterus and sutures should not enter the uterine lumen. Blood clots should be removed from the surface of the viscera and the abdomen where possible. Closure of the peritoneum, muscle layers and skin is routine.
In cases of dystocia where the calf has been confirmed dead, a embryotomy/fetotomy may be indicated.
These procedures should always be done under epidural anaesthesia, with every care taken to protect the dam’s soft tissues from damage by any equipment.
If embryotome wire is employed, a suitable guard should be used; a metal embryotome is ideal, but substitutes, such as hosepipe, can also be used.
These guards protect the soft tissues of the reproductive tract from direct trauma by the wire and dissipate any heat.
If an embryotomy is undertaken, a good plan is essential; parts of the calf presenting, what can be safely removed and what will be left once a part has been removed should all be considered.
Embryotomies can be performed in multiple steps to ensure a successful outcome (Figure 4). If the calf is emphysematous, incisions into the skin may release gas, making the procedure more straightforward.
Decomposing calves can cause additional problems if pieces of their skin, soft tissue or bone break off and are left in utero; they may act as a nidus for further infection or cause secondary trauma.
Where possible, embryotomy incisions should be made to remove whole appendages and/or the head. It is important any sharp edges remaining on the fetus are protected from causing damage to the dam when removed.
Numerous outcomes of difficult calvings can judge failure or success. Farmers should also be aware of a number of potential sequelae to dystocia.
These, their onset/duration and treatment options are detailed in Table 2.
Difficult calvings are common visits for farm animal vets and important for client relationships. Prompt decision making and good communication can help to make even the most challenging situation a successful one.
