What do you do when you have a cow that is springing with calf but over her due date? I get asked that question quite often and my answer is almost always an unequivocal "Induce her!"
The only reason I say my answer is almost always and not always is the not so rare case of a wrong breeding date. Since the cow has a 21 day estrous cycle, we can usually differentiate a cow that's overdue from a cow 3 weeks away from delivering her calf.
cesarean section or fetotomy may be the result.
Prolonged gestation is not the only indication for induction of delivery; there are several others. If a bigger than normal calf is expected based on the calving ease score of the sire, an induction may very well spare the cow and farmer a lot of grief. We all know that a cow doesn't necessarily have to be overdue to have a large calf.
Many times a farmer is expected to be away from the farm for a few days around the time a particularly special cow is due or a special calf is to be born. In that case, induction is indicated to allow the cow to be assisted in the event that there is an abnormal fetal presentation or otherwise unusual complication. I have prescribed induction more than once for this reason.
Rarely, dairy cows may develop a condition known as pregnancy toxemia during the last month of gestation. This is basically a bad case of ketosis before she calves and can be potentially deadly for the cow. In my experience, pregnancy toxemia is usually secondary to some other disease, but one of the treatments is to deliver the calf in order to lessen the metabolic burden on the cow.
Occasionally, we see a cow that is unable to get up due to an injury yet she is pregnant and within a couple weeks of her due date. In this case, we can induce the cow to calve early to save the calf, and then humanely euthanize the cow after the calf has been delivered.
One of the more common reasons that I prescribe induction is severe udder edema. Dairy cows with udder edema that has the potential to cause breakdown of the median suspensory ligament should always be considered for induction. One of the side benefits of inducing cattle with severe udder edema is that dexamethasone, the drug that induces labor, also helps to reduce udder edema.
Speaking of dexamethasone, it is the drug of choice for inducing labor in late gestation cattle. It will only work if the developing fetus is alive since it depends on hormonal changes brought about by the fetus and the placenta. Dexamethasone is often given along with prostaglandin F2 alpha, not because it makes it work better, but it reduces the complication of retained placenta in induced cattle.
Many are reluctant to induce calving because of the risk of retained placenta and potential unthriftiness of the calf. It is true that induction does increase the risk of these complications, however so does a high birth weight resulting from prolonged gestation. Most farmers that have instituted induction protocols when indicated are quite pleased with the results.
It is generally regarded as safe for the fetus to induce labor up to 14 days prior to the due date. The more immature the calf is, the higher the risk of breathing complications and death. Another one of the side benefits of dexamethasone is that it promotes maturation of the fetal lungs immediately prior to delivery.
Once the induction drugs are given, calving usually happens within 24 to 48 hours. Longer times are possible if induction is done more than a few weeks before the due date. The closer an animal is to her due date, the closer to 24 hours she will deliver. Both dexamethasone and prostaglandin F2 alpha are prescription medications so consult your veterinarian to see if induction of labor might be indicated in your herd.