There have been several instances in my practice where an unexplained delay in calving has resulted in stillborn or weak calves because the calving process was too long. I would hazard a guess most producers have run into this problem at one time or another. Although not much research has been done on this subject, it is likely multifaceted, I will attempt to give some thoughts on causes or prevention and potentially what you should check for when the incidence gets too high.
I call it uterine inertia. It occurs when a cow has gone through the initial stages of parturition, her cervix has dilated, yet there is very little contractility to the uterus. These are the cows where you may or may not have seen the waterbag, yet one to two hours later the cow is still essentially chewing her cud, and not initiating the process. Hopefully you would notice it, but nowadays with less observance during calving season, especially at night, prevention is the key.
There are many reasons for uterine inertia but I will highlight just the common ones.
Cows that are too fat or lacking exercise don’t develop the musculature to contract. If any of you have gone to prenatal classes they stress the women practising “Kegels” which is working the musculature in the vaginal vault so childbirth is easier. The same theory applies to cattle. Bred show cattle need to have exercise once the show season is over. The best way is walking. Feeding out far from the yard making them walk in for water and having the minerals in a different location goes a long ways to decreasing abdominal fat and increasing muscle tone for calving. Conversely too thin cattle have no muscle and uterine contractions are weak and parturition delayed.
We need cattle in the 2.5-3.5 condition score out of five at calving getting as much exercise as possible to minimize calving issues.
Minerals play a huge role in cattle health overall and that is no different at calving. We all know the deficiencies of vitamin A and E or selenium have on the incidence of retained placentas. Macro minerals especially calcium and phosphorus play a huge role in the ability of the uterus to contract. We especially see this in milk cows with a full-blown milk fever (Ca deficiency). If it occurs before calving it causes the cow to go down, delays calving, and increases the incidence of prolapsed uterus after calving. Giving calcium intravenously in these instances will get the cow up and the uterus contracting. In several instances of uterine inertia I have found the calcium levels to be low normal. Extra supplementation has improved it somewhat but that would be a solution to discuss with both your veterinarian and herd nutritionist.
Whenever you move calving cows into the barn depending on the degree of nervousness of the cow uterine contractions may stop. This process is started by a complex interaction of hormones whereby one negates the effects of the other. I am talking about adrenaline (epinephrine) counteracting the effects of oxytocin which is one of the hormones necessary for uterine contractions and milk let-down. This is why the more nervous the cow, the less likely she is to reinitiate uterine contractions. And, if she’s being milked later she will hold up her milk. As long as the cervix is totally open small amounts of oxytocin can be given to start uterine contractions.
This is a prescription drug and only small amounts are given so have your herd veterinarian prescribe some to have around. It is also a hormone which needs to be refrigerated. Tranquilization may also be effective in calming an excitable cow and allowing their own natural oxytocin to take over. We must realize whenever a cow is moved or brought into a strange environment right at calving that contractions may diminish. The question then becomes when do I intervene and the answer for me is if you are present and there has been no progress calving in one hour check her out.
Often hooking up chains to the feet and applying light traction, and being patient, will start the contractions. If the feet are way down inside the uterus but the cervix is open that is when oxytocin may be helpful. We must have the cow’s uterus contracting in order to pull a calf otherwise we have a forced extraction where the health of both the calf and cow is in jeopardy.
It is always amazing to me the force of the contractions that can be brought on by only slight traction. If a cow is more relaxed and down on her side in a more natural position she is more likely to push. As can be seen by this summary the cause of a lack of contractions is very variable so always consider this every time you are assisting.