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Improper cervical dilation at calving

Recognizing when it's happening is your first step

Knowing when to act to help ensure a successful birth is crucial if problems occur during calving.

One of the hardest calving dilemmas you or your veterinarian face, is improper cervical dilation. Before expulsion of the fetus the cervix normally relaxes, softens and opens up essentially as wide as the vagina to allow the fetus to enter the vaginal vault. When this does not happen normally, or is delayed, the health of the fetus and dam may be in jeopardy.

Close to term, the cervix is to the front of the vagina and the opening is normally about one to two fingers wide. It would be like sticking your finger in a doughnut. So when a cow is straining somewhat and you do a vaginal exam and find this condition, what is your next step?

What I do, when I think a cow is calving and find a closed cervix, is wait and re-examine her a couple hours later. If I find the cervical opening has increased, that tells me calving is progressing. If there is no change you now have to decide if this is a false alarm or an early indication that there is a problem.

At this juncture some vets may have you give the cow more time and some may opt to perform a caesarian section. Each case is different.

Another issue involves a cervix that will only open wide enough to get the front two legs through. This is not common but does require different interventions depending on how it is progressing.

In a normal birth the cervix is right out of the way when we get to the expulsion of the fetus. When it isn’t, the veterinarian will first try to dilate the cervix manually to facilitate delivery.

If the nose and head can be partially delivered a slight amount of traction may help dilate the cervix fully. This is where one has to be really careful as too much traction is both stressful on the calf and may rip the cervix causing excessive bleeding and possibly be fatal to the cow. If no progress is made, a caesarian section is performed to get a live calf, and save the cow but she should be marked for shipping the next year.

Some of these cows with a partially opened cervix may have had a difficult calving the year before which caused some damage to the cervix.

Even though there is a lot of room in the pelvis and vaginal opening, C-sections are the only solution for a cervix that won’t dilate. As mentioned, a forced extraction through a partially open cervix puts both the cow and calf’s lives in jeopardy so a C-section is a win-win solution most times.

You can usually tell if the cervix will open with some manual dilation. It is soft and supple and you make progress in 10 or 15 minutes. If the cervix has a hard fibrous feel, no amount of time will get it to open so jumping to a C-section hopefully will provide a good result for cow and calf.

There are a couple of other instances where a partially closed cervix can be encountered.

After correcting a torsed uterus your veterinarian will usually encounter a partially closed cervix . Because of the twist the cervix cannot fully dilate, but upon correction it can generally be dilated by hand. There is a tendency to let it dilate on its own but I have done that and ran out of time resulting in a stillborn calf. Now I proceed to dilate the cervix manually to facilitate extraction. Generally these cervixes are soft and supple and in my experience easy to dilate.

The other condition is a delayed calving that results in death of the fetus. This could be because of a malpresentation such as a breech birth where the cervix is opened, but straining does not ensue, time runs out and the calf dies, bloats up and straining ensues. Often the cervix can start to close up, much as it would after a normal calving. These cases may require a fetotomy or partial fetotomy, in order to salvage the cow.

Although infrequent, partial cervical dilation does require serious intervention by a veterinarian or yourself, depending on your level of experience. Recognizing them is the first step. If you think a cow is in labour and no progress is being made, do a vaginal exam to see if an improper cervical dilation is the cause. By recognizing it early you have the time to intervene, and provide a favourable outcome. Have a great calving season.

About the author


Roy Lewis is an Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.



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