There have been several instances during my career when an unexplained delay in calving has resulted in stillborn or weak calves because the calving process was too long.
I would guess that most producers have run into this problem at one time or another. Although not much research has been done on the subject and it is likely multifaceted, I will attempt to give some thoughts on causes and prevention and potentially what should be checked for if the incidence becomes too high.
I call this problem uterine inertia, in which a cow has gone through the initial stages of parturition and her cervix has dilated, but there is very little contractility to the uterus.
These are the cows where you may or may not have seen the water bag, but one to two hours later the cow is still essentially chewing her cud and not initiating the process. Hopefully you will notice this, 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 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 encourage women to practise keegles, which work the musculature in the vaginal vault so that 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 far from the yard to make the cows walk in for water and having the minerals in a different location goes a long way to decreasing abdominal fat and increasing muscle tone for calving.
Conversely, cows that are too thin have no muscle, which means uterine contractions are weak and parturition delayed.
We need cattle in the 2.5 to 3.5 condition score at calving and 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 how deficiencies of vitamins A and E and selenium can affect 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, where a full-blown milk fever (calcium deficiency) that occurs before calving can cause the cow to go down, delays calving and increases the incidence of a prolapsed uterus after calving.
Giving the calcium intravenously in these instances will get the cow up and the uterus contracting. In several instances of uterine inertia, I have found calcium levels to be below normal. Extra supplementation has improved it somewhat, but that would be a solution to discuss with your veterinarian and herd nutritionist.
A calving cow’s uterine contractions may stop when moved into the barn, depending on the degree of nervousness. This is triggered by a complex interaction of hormones in which 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 nervous cows are less likely to reinitiate uterine contractions and more likely to hold up milk if being milked later.
Small amounts of oxytocin can be given to start uterine contractions as long as the cervix is totally open. 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 that needs to be kept refrigerated.
Tranquilization may also be effective in calming an excitable cow and allowing its own natural oxytocin to take over.
Contractions may diminish whenever a cow is moved or brought into a strange environment right at calving. The question then becomes, “when do I intervene,” and the answer for me is, “check her out if you are present and there has been no calving progress in one hour.”
You can often start contractions by hooking up the chains to the feet and applying light traction and being patient.
If the feet are way down inside the uterus but the cervix is open, that is when oxytocin may be helpful.
A cow’s uterus must be contracting when pulling a calf; otherwise we have a forced extraction in which the health of both the calf and cow is in jeopardy. The force of the contractions with slight traction is always amazing to me.
A cow is more likely to push if it is more relaxed and down on its side in a more natural position.
The cause of a lack of contractions is very variable, so always evaluate this every time you are assisting. There must be an underlying reason.
Roy Lewis works as a technical services veterinarian part time with Merck Animal Health in Alberta.