Dan Goehl, DVM
Calving season is a time of nervous anticipation. We look forward to the new crop of calves and seeing the fruits of the past year's efforts hit the ground running. Calving problems (or dystocia) are a concern for cow calf producers.
The occurrence of dystocia has been reported to be approximately 10-15% in first-calf heifers and 3-5% in mature dams. These difficulties threaten the health of both dam and calf. In addition to the impact on animal health, difficult calvings cause cows to take longer to breed back. Delayed breeding results in a longer calving season next year or open cows at pregnancy test time.
Many factors influence dystocia rates in beef cattle and fall into two major categories: abnormal fetal to dam size ratio and abnormal physical presentation. The normal birth process relies on an appropriate relationship between the size of the fetus and the birth canal. If the fetus is too large or the birth canal (pelvis) is too small calving problems will likely ensue. The advent of Expected Progeny Differences (EPDs) for birth weight and calving difficulty (in some breeds) greatly enhance the ability to use genetic selection to prevent calving problems of this nature. Prevention through planned breeding and appropriate genetic selection is the best method to limit calving problems due to these factors.
Abnormal physical presentation of the calf also causes birthing problems. The normal presentation for calving is an anterior presentation. The easiest way to explain this is to think of Superman or a diver. The calf should present with both front feet first and his head tucked between his legs as if he was flying through the air (Superman) or diving into a pool. If the calf doesn't present in this manner or twins are present, calving may not proceed normally regardless of calf size.
All tough calvings can not be avoided and understanding the normal birthing process is the key to appropriate management. The most difficult decision is knowing when or if to intervene. Assist too late in the birthing process and the calf, or worse yet the cow, may perish. Assist too soon and the cow may not be dilated enough to give birth. Intervention strategies should be based on an understanding of the normal birthing process.
Pre-calving cows develop their mammary glands or "bag up" 2-3 weeks before delivery. Milk builds in the mammary glands in preparation for the upcoming event. As the dam nears calving a relaxation of ligaments in the pelvis occurs giving the vulva a characteristic fluctuation when the dam walks (often referred to as "springing"). It is not uncommon to notice a mucus plug several days before calving. These changes lead to the beginning of the parturition (birthing) process which can be broken into three stages.
Stage One starts with mild uterine contractions progressing to dilatation of the cervix. The cervix is a cartilage and muscular ring that controls communication between the uterus and the outside world. It is closed during pregnancy to keep harmful environmental elements out, but must fully dilate to allow the calf to pass through. Cows in this stage are often restless, not likely to eat, and may isolate themselves from the herd. Some animals may act uncomfortable or colic. During this stage, uterine contractions push the calf toward the birth canal. The conclusion of this stage is the rupture of the placenta and discharge of amber-colored fetal fluids (or in other words, the cow's water breaks). Stage One usually lasts 1 to 12 hours, with 1 to 4 being most common. If fetal membranes (water sac) are exposed with no further progress in 2-3 hours, intervention should be considered.
Stage Two begins as the calf enters the birth canal. The act of the calf entering the birth canal stimulates strong abdominal straining. The cow often lies down during this phase and uses her full force to push the fetus into and through the birth canal. For a calf in normal presentation, the front feet are the first to exit the birth canal with the bottom of the hooves facing down. If the head or a tail is exposed prior to seeing feet or the feet appear to be upside down, it is time to consider immediate assistance. Progress is the most important thing to observe during this phase; once the cow starts pushing the calf through the birth canal, she should make consistent advancement toward expulsion of the fetus.
After Stage One ends (breaking of the water) and hard straining begins, the feet of the calf should be visible within 30-60 minutes. If no part of the calf is visible after one hour of strong straining, intervention should be considered. Cows should be closely observed during this stage as in some cases straining may stop after a period of time. In breech calves (backwards calves that present the tailhead and hips instead of the front feet), the dam may not strain or quit straining due to a lack of progress. These cows should be evaluated to determine if straining stopped because she was still in Stage One or if she is in Stage Two and needs assistance to deliver the calf.
After the feet are exteriorized, a 20-minute rule should be followed. If at any point 20 minutes passes without more of the calf exposed (i.e. the cow is pushing, but the calf is not moving out), intervention should be considered. This stage should take no more than 1-2 hours and concludes with the expulsion of the calf.
Stage Three is the process of expelling the fetal membranes (placenta, "after birth") through the birth canal. After eight hours this can be considered abnormal, but anything less than 24 hours is not considered retained. If fetal membranes are noticed protruding from the birth canal at 24 hours past calving, contact your veterinarian regarding treatment options. Retained placentas can lead to reproductive tract infections and cause subsequent problems with breeding. Treatments for this condition are more effective if the problem is identified early compared to managing the difficulty after 3-4 days.
There are no clear cut timelines that dictate when to get involved in a difficult calving. Intervention and assistance in the calving process should not be taken lightly. It is important to understand the stages and progression of labor. Often timely intervention is the key to a successful calving but at times no interference is just as important.
Anytime assistance is given, a few simple rules of thumb should be followed for the best results.
- Evaluate the situation and realistically assess your ability to correct the problem.
- Be sure to understand the current presentation and the necessary corrections to allow delivery with minimal force.
- If you feel uncomfortable or unsure of the next step, call your veterinarian for assistance.
- If you assist and are not making forward progress in 15-20 minutes, it is time to try another technique or call for assistance.
Forcing the issue is not helpful to the cow or the calf. Extracting a calf with a difficult presentation is not a matter of simply pulling harder. In fact, if the extraction takes more than the force applied by two men, alternative means should be considered (i.e. reposition and try again or cesarean section). If the calf is not in proper position or simply too big, excessive force only serves to cause health problems for the animals and frustrations for the people.
Prevention is the best solution for calving problems, but difficult births are still a fact of life in the best managed cow herds. The key to success is understanding the normal birthing process and knowing when or if to assist the dam.
If in question at any time, contact your veterinarian for advice or assistance to deal with the problem. As we often have busy days during calving season, it is advisable to call your veterinarian and give warning when you realize you may need help.
Dan Goehl, DVM, and his wife own and operate Canton Veterinary Clinic in Canton, MO, where Dan works primarily with stocker and cow/calf beef operations. Dan is also partner in Professional Beef Services, LLC, which offers herd consultation and helps in data management and marketing of beef cattle.