Causes of calving difficulty (dystocia) may be separated into two categories. 1 ) Contributing causes can be identified before the process of giving birth (parturition) begins. 2) Immediate causes are those that can only be recognized after a cow is in labor. At that point dystocia cannot be prevented; only the severity can be minimized. However, the incidence of dystocia can be reduced by management decisions based on understanding the contributing causes.
The younger a heifer is when she calves, the more difficulty she will have. Regardless of age at calving, the highest incidence of dystocia is in first-calf heifers. Second-calf cows have more dystocias than mature cows.
Birth size and shape are heritable. Sires can be chosen to reduce calving difficulty. Using a sire breed larger than dam breed in a cross-breeding program tends to increase calving difficulty. However, within each breed are bulls that contribute less difficulty than others. Ease-of-calving data has been tabulated on some bulls used widely in artificial insemination programs.
Level of nutrition plays an important role in determing age and weight at puberty and parturition. Most heifers reach puberty before they are large enough to be bred and calve without experiencing difficulty. Malnutrition may result in an undersized or misshapen skeleton, including the pelvis. Over-feeding heifers during late pregnancy to compensate for small size at breeding may favor growth of the fetus, upsetting the balance between fetal size and pelvic diameter. Excessive energy intake may result in deposition of fat in the pelvic cavity, favoring dystocia. An increased incidence of calves presented backward in feedlot heifers has been observed. One possible explanation is that abdominal fat prevents repositioning of the fetus after some critical time during gestation.
Diseases that cause late-term abortion or fetal death often result in dystocia. The dead fetus may be presented abnormally or may be distended with fluid or gas. Maternal effects of abortion or fetal death include uterine inertia, failure of the birth canal to dilate, and retained after-birth (placenta). Previous injuries may result in a misshapen birth canal or may produce pain during labor that interferes with delivery.
A large fetus relative to the diameter of the birth canal is the greatest cause of dystocia in heifers calving for the first time. This also accounts for many calving difficulties in second-calf cows and small cows bred to bulls of a larger breed. The other major cause of calving difficulty, mal-position of the fetus as it approaches or enters the birth canal, may occur in any cow regardless of age or size. In animals that ordinarily have one offspring, there is only one normal position of the fetus during birth: right side up, front end first, feet and head extended.
Relatively infrequent causes of calving difficulty include abnormalities of fetus or birth canal, failure of birth canel to dilate, or failure of uterus or abdominal muscles to contract effectively. These less frequent situations usually require professional assistance.
Normal parturition is arbitrarily described in three stages. First stage begins with uterine contractions, includes dilatation of the cervix, and ends with entry of the fetus into the birth canal. Restlessness and isolation from the herd may be the only observable signs during this stage. Heifers are generally more restless than older cows. They may appear colicy, lying down and getting up frequently or kicking at their abdomen. The first waterbag may appear toward the end of the first stage. Stage one continues for two to six hours, or sometimes longer in heifers.
Second stage comprises passage of the fetus through the birth canal. During this phase the cow actively participates in delivery. Fetal membranes appear and rupture ahead of the fetus, providing lubrication for its passage. Point pressure exerted in the cow's pelvis successively by the head, shoulders, and hips of the fetus intensify abdominal contractions. Mature cows are normally in second stage parturition less than two hours. Heifers may normally require three or four hours.
Once feet are showing, they should progressively advance and not appear and disappear with each abdominal contraction. If feet are protruding through the vulva with soles down, they are usually front feet. If soles are up, they are usually hind feet. In a normal forward delivery the front feet are side by side with jaws resting on forelimbs and muzzle at about the fetlocks. The calf passes through the birth canal in an arc. As it enters the pelvic inlet, direction of travel is toward the tailhead of the cow, then parallel to the cow's back, then ever more ventrally. As the calf's hips enter the pelvis, direction of travel is toward the cow's rear feet. This arc keeps the calf high in the pelvic inlet and takes advantage of the widest horizontal diameter of the pelvic opening.
Third stage includes passing fetal membranes and closure of the cervix. The placenta is usually expelled within eight hours, after which the cervix secretes a thick mucus that helps prevent infection from entering the uterus. Within 24 to 36 hours a person's hand will not pass through the cervix; by four days only two fingers can be introduced.
Limit the calving season to as short a period as practical. With a short calving season it becomes more practical to observe cows often enough to provide timely assistance. It is important to have a calving watch so all signs can be observed and help given when needed, without interrupting normal parturitions for unnecessary examinations. Record expected calving dates of individuals; this is practical only with artificial insemination or hand breeding but is very helpful in determining which cows to watch more closely.
Cattlemen should develop a competence and confidence in determining when to intervene, in aiding deliveries, and in assessing the need for professional assistance. A cow should be examined if she has labored two or three hours without progress or if the calf has not been born within two hours after appearance of a waterbag. Overzealous intervention before the cervix is fully dilated may result in severe injury to the cow as well as the calf.
A cow can be more easily examined when she is standing. Lying down forces her abdominal organs and the fetus into or against the pelvic cavity. If a cow will not or cannot rise, it will help to position her upright on her sternum and stifles with her rear legs extended behind her.
The vulva and surrounding area as well as the hands and arms of the person making the examination should be washed thoroughly with warm water and soap. Cleanliness at all times during examination and delivery cannot be over-emphazized. Thoroughly lubricate the arms of the examiner and the birth canal. Lubricating gels are available commercially, or one can be prepared by dissolving mild soap flakes in a small amount of hot water and allowing the solution to cool.
Carefully examine the birth canal to determine if it is fully dilated and free of twisting and obstruction. Evaluate the size of the fetus in relation to the diameter of the passage. Pull on and pinch a foot of the calf to determine if it is alive. Examine the fetus to determine its position and the presence of any abnormal structures. Normal birth is possible only with the fetus in anterior or posterior presentation, right side up, with head and limbs extended. The possibility of twins should always be considered.
Determine whether the feet presented are front or rear feet. Front limbs have two joints between the hoof and elbow, whereas rear limbs have only one joint between the hoof and hock. A cow is more apt to require assistance with a posterior delivery than with an anterior delivery. Rear limbs are not as effective in initiating dilatation of the birth canal and stimulating abdominal contractions as is the head, the tail head of the calf tends to impact against the cows back bone, the hair of the calf lies the wrong way, and compression of the calf's abdomen causes its rib cage to expand. With posterior presentation, flow of blood through the navel cord is impeded early in delivery, and the calf's head is submerged in fluid. Once the hips enter the birth canal, delivery must be rapid for a live birth.
If examination reveals abnormalities of the fetus or birth canal, failure of the tract to properly dilate, or a calf apparently too large for safe delivery through the birth canal, professional help should be sought at once.
Provide adequate facilities and equipment for aiding deliveries. A large well-lighted stall should be reserved as a maternity area. It should be sanitized and well bedded each time it is used.
Obstetrical chains are preferred to other traction aids because they are more easily disinfected, and handles are available that may be quickly attached anywhere along their length. Two Chinch chains, one 60-inch chain, and two handles are desirable. Equipment should be cleaned and boiled in mineral oil after use to prevent spread of disease and rusting. Cotton sash cord works well but should be discarded after use. A good mechanical calf puller is needed, not for the amount of pressure it will exert, but for the directions of traction that can be achieved. Other methods of applying traction, such as block and tackle or fence stretchers, apply no opposing force to stabilize the cow and allow pulling parallel to her body only.
Traction should be applied cautiously until the vagina and vulva are fully dilated. Tearing the cervix or vagina may result in sterility or death of the cow. The whole purpose of the procedure is to deliver a healthy calf and prevent injury to the cow.
If forced extraction is required, chains should be placed carefully on the extremities. If fetal membrances interfere, they should be torn away. Place the noose of the chain above the fetlock and a half-hitch around the pastern. This reduces the risk of fracturing a bone or pulling off toenails.
When one or both front or rear limbs or the head is retained in the uterus, manipulation of the fetus is required before traction is applied. Fetal parts must be guarded with the hand to avoid tearing the uterus. Some manipulations can be made with one hand; others require opposing force. Opposing force is accomplished by placing a loop of chain on a foot or the lower jaw and pulling on the chain with one hand while repelling the poll, shoulder, elbow, hip, or hock with the other hand. Care must be taken that the teeth or toes do not tear the uterus.
To apply traction to the head, pass the chain loop over the poll behind the ears and through the mouth. This causes the mouth to open, so care must be taken that the calf's teeth don't lacerate the birth canal. Limit head traction on a live calf to relieving impaction of the head and extending the neck; pulling on the head to move the body may cause injury to the calf's spinal cord.
If the muzzle appears before one or both feet, the elbow(s) may be impacted against the pelvic brim or the forelimb(s) may be retained in the uterus. An impacted elbow can usually be corrected by moderate traction on the foot, however, it may be necessary to apply opposing force to the head to make room for correction. If one or both forelegs are retained in the uterus, it is often necessary to push the head back through the pelvic inlet to correct the problem. If it is very difficult to get the head and both forelegs into the birth canal at the same time, mechanical traction should not be applied. Either the positioning is faulty or the passage is too small to accomodate the calf.
Shoulder lock occurs when the calf's shoulders become impacted at the pelvic inlet. To relieve a shoulder lock, apply moderate traction to the head and alternately apply traction to the forelimbs so the shoulders are "walked" through the bony pelvis one at a time. If the shoulder lock is severe, a caesarian section should be considered; a shoulder lock relieved with difficulty may be followed by a worse hiplock.
Hip lock (calf's hips impacted at pelvic-inlet) should be dealt with promptly. The calf usually doesn't survive long in hip lock, and the cow may become paralyzed due to excessive pressure on the nerves to her hind limbs. Direction of traction is very important. If a hip lock develops with the cow standing, fasten the forelimbs of the calf together with a short chain, step up in the stirrup formed by the chain, and swing your weight forward between the hind feet of the cow. Hip lock can often be corrected in a cow lying down by repelling the fetus a little, then applying traction over the uppermost rear leg of the cow toward her shoulder. A chain can be placed around the abdomen of the calf and traction applied downward. A 45° rotation of the calf will aid in relieving a hip lock because the vertical diameter of the pelvis is greater than the horizontal diameter.
A calf presented backward must be delivered backward. It is not possible to turn a calf around in a cow. Lubricate the fetus and birth canal before delivery is attempted. Place chains above the calf's hocks and attach the calf puller before applying traction. Once the hips enter the birth canal, traction should be rapid and uninterrupted. Alternating traction on the rear legs and rotating the fetus 45° may help. If it is very difficult to get the hips through the pelvic inlet, a caesarian section may be required. This decision should be made before the hips are forced into the birth canal and the life of the calf jeopardized.
If a calf is presented butt first (breech), the cow often does not enter second-stage labor as point pressure is not exerted within her pelvis to stimulate abdominal contractions. The tip of the calf's tail may be protruding through the vulva or lying in the vagina. The subtle signs of first-stage parturition often go unrecognized, and the cow appears sick or discharges a putrid fluid two or three days later.
A breech presentation may be relatively easy or very difficult to deal with. Important variables include how soon the problem is recognized, whether or not the cow will stand during manipulation of the fetus, the amount of abdominal space for manipulation, how rigidly the calf's hocks are extended, and how hard the cow strains.
The calf's hips must be repelled forward, upward, and toward one flank, the hocks flexed, and the feet extended backward into and through the birth canal. It is very helpful if the cow will stand during manipulation of the fetus. The calf should be repelled between labor pains, and care must be taken not to tear the uterus by pushing too hard on the calf. If manipulation is difficult, epidural anesthesia (a local anesthetic injected into the cow's spinal canal) should be administered to stop straining.
Efforts by the cattleman to assist delivery should be limited to thirty minutes, and should not exceed his technical capabilities. To delay calling a veterinarian when his help is needed can result in unnecessary injury or death of the cow as well as the calf.
Provide adequate aftercare for the calf and its mother. Two emergencies may exist upon completion of the delivery: the calf may fail to breathe, and the cow may attempt to prolapse her uterus. The calf can be stimulated to breathe by inserting a straw 2 or 3 inches into the nostril, by brisk massage, and by slapping the chest. Excess mucus should be cleared from the airway, and the head kept lower than the chest until the calf is breathing. Brisk massage with a rough cloth, such as burlap, will also stimulate circulation. Commercial aspirator-respirators are available and are helpful in aspirating mucus and administering oxygen. Directions provided by the manufacturer should be followed.
The cow should be encouraged to get up and move around so her uterus will fall into the abdomen and labor will cease. Straining can sometimes be interrupted by vigorously gripping the cow's spine at the middle of her back. Examine the reproductive tract for tears and the presence of another calf.
After emergencies are averted, saturate the calf's navel with an iodine solution. Within fifteen minutes after birth, the calf should nurse the cow or be given a quart of colostrum by nipple or esophageal feeder. Inject cow and calf with broad spectrum antibiotics. Avoid putting boluses, especially those containing urea, in the uterus. They are irritating to uterine mucosa and may result in delayed conception. If the placenta is retained, continue to administer broad-spectrum antibiotics daily until it is passed. If the cow goes off feed or in any other way appears sick, consult a veterinarian.
The incidence and severity of dystocia can be reduced by sound management decisions in breeding, nutrition and herd health. Some calving difficulties will occur regardless of precautions taken. Losses from dystocia can be minimized by:
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This page was last updated on November 16, 2002