Normal calving process 

Calving occurs due to a complex interaction of physiological processes 1. The normal calving process begins when the fetus has matured enough that the uterus and placenta are unable to provide the demands of the fetus. An increased production of cortisol and other steroid precursors will cause a fetal stress reaction. Uterine muscles will respond to these hormone changes by contracting as the cervix dilates. Once the cervix is fully dilated, the calf is forced into the birth canal. Further pressure is produced in the vagina and stimulated abdominal pressing. Once this process starts, it is irreversible. The calf must be delivered promptly or problems, including death, could occur to either the calf, the dam, or both animals. 

Stages of labor 

Cows and heifers will all go through the same three stages of labor, although cows tend to progress more quickly than heifers. Prediction of calving times can be valuable, yet these should be used as guidelines and your monitoring of each calving animal should guide your decision making. It is important to monitor both groups closely and remember to pay close attention to the heifers in case they need assistance. Dilation of the cervix begins shortly before calving during the preparation stage. Once this starts, calving usually occurs within 24 hours. Dystocia can occur at any stage when the dam fails to progress normally. Below are common signs to look for in each stage of labor ^1,2. 

• Stage I Labor: Calf has moved into position for expulsion. Stage ends when ‘water bag’ is seen or liquid comes out of vulva. 
• Time frame: Cows should progress within 1 hour. Heifers may take up to 4 hours. 
• Signs can include: Mucus or discharge from vulva, standing away from herd, elevation of tail or tail switching, signs of discomfort and restlessness. In mature cows, this stage could go unnoticed. 
• Stage II Labor: Begins with entrance of fetus into pelvic canal and appearance of water bag at the vulva. Abdominal contractions begin. Stage ends when calf is delivered. 
• Time frame: Stage can last from 30 minutes up to 4 hours in cows but intervention should be assessed at 2 hours. Heifers could take longer. It is important to check the cow or heifer every 30 minutes unless you see abnormalities. If progress is being made, let her push on her own. If no progress is made, excessive fatigue or stress to the cow or calf is evident, or the cow/heifer has quit trying, then a vaginal exam should be performed to determine the next step which could include assisting the calving yourself or calling your herd veterinarian for surgical intervention. 
• Stage III Labor: Expulsion of fetal membranes. 
• Time frame: For both cows and heifers, this should take 8-12 hours. Do not attempt to manually remove fetal membranes from the uterus as this can increase the risk of bleeding, infection, and future fertility problems. Work with your herd veterinarian if retained fetal membranes are suspected. 

Dystocia management and calving intervention 

Several factors can contribute to dystocia in cattle. Fetal-maternal mismatch (calf is too big or dam is too small) is the most common cause, though there are many other factors. Regardless of the reason, if no progress is being made during the calving process for either a cow or a heifer, a vaginal exam should be completed to assess the situation. If you are uncomfortable with this assessment, contact your herd veterinarian early in the calving process so timely intervention is possible ³. 

Cleanliness is very important during the calving process. In your calving toolbox, you should have: a clean bucket, disinfectant such as betadine or chlorhexidine, OB lube, obstetric chains, handles, bag of rectal sleeves and latex gloves, cow halter, and a clean/dry calving area (if possible). Bright lights are a must especially for late night calvings. If you have a calf puller or calf jack, it is essential that everyone is trained properly on how to use it safely and also that it is functioning correctly. Calving chains and handles should be placed in a bucket with warm water with chlorhexidine, dilute betadine, or dilute Ivory soap. To prevent injury to the calf, chains should be applied properly in a half hitch above and below the fetlock (Figure 1). 

Be sure the cow or heifer is fully dilated before moving on. Manual pressure can be applied using your forearms, hands grasped, and extending your elbows out in a V-shape to gradually dilate the cervix and prevent tearing. When figuring out how the calf is positioned, it is important to remember these terms in describing ¹: 

• Presentation refers to whether the calf is coming frontward, backward, or transverse. 
• Position refers to whether the calf is right side up or upside-down with only right side up being considered normal. 
• Posture refers to the relationship of the calf's legs and head to its own body. 

Checking the position of the calf will determine how to place chains and move forward. Calves may be pulled frontwards or backwards as long as both legs are in the same direction (Figure 2 and 3). However, backward presentation and any other presentation should be considered abnormal and grounds for intervention.         

Having contact information for your herd veterinarian posted in the calving area or barn is a key preparation step before calving season. Even with close monitoring, timeliness of intervention will improve the success of the dystocia for the calf and the dam. Calling the veterinarian sooner can provide a better outcome in case a Cesarian-section or fetotomy is needed. Close monitoring of cattle during calving season improves the chance of identifying problems early in the process. Both the calf and dam will benefit from early intervention if needed. Follow your herd health plan or veterinarian’s instructions on care of the cow and calf after dystocia, including pain management, colostrum administration, or other advice. You can refer to the following resources or the BQA National Manual for further tips on biosecurity, record keeping, and herd management at bqa.org.   

¹ Mortimer 2017. Calving and handling calving difficulties. https://beef.unl.edu/documents/herd-health/2015-Calving-and-Handling-Calving-Difficulties-December-2017.pdf (Accessed January 10, 2022). 

² Extension Animal Science Program, Texas A&M University. Recognizing and handling calving problems. https://agrilifeextension.tamu.edu/library/ranching/recognizing-and-handling-calving-problems/ (Accessed January 10, 2022).   

³ Hilton 2019. Pulling a calf? Here’s the best way. https://www.beefmagazine.com/calving/pulling-calf-here-s-best-way (Accessed January 10, 2022).   

This article was originally published in the February 2022 issue of NCBA National Cattlemen newsletter.