By Jeffery S. Claborn DVM
How long do we wait on this cow Doc? A question I have heard many times from new people entering the cattle business & experienced cattlemen. A basic knowledge of the physiologic steps occurring within the cow at calving time aids in determining the time to assist.
There are 3 stages of parturition. The first stage involves the initiation of uterine contractions that result in dilation of the cervix. The calf has not entered the pelvis at this point and is relatively free from harm. Stage 1 usually lasts a few hours, but can last up to 24 hours.
Stage 2 begins as the calf enters the pelvis (birth canal). The chorioallantoic membrane (water-bag) breaks and the calf is generally delivered within a few hours.
Stage 3 involves the expulsion of afterbirth. Cows that have not passed the afterbirth by 72 hours post-calving need to be cleaned and medicated. If the cow appears to be sick, removal of afterbirth and medicating is done sooner. It is during Stage 2 that the calf is most vulnerable to hypoxia (low oxygen) and pressures resulting in facial/throat swelling. With this in mind, the following guidelines can be applied to determine when to assist with delivery:
1) The water-bag has just started to protrude from the cow- If the cow is not pushing or showing any signs of labor, a 5 hour waiting period is generally acceptable. However, the 5 hour wait period is over if the cow proceeds to pushing and straining.
2) If no progress occurs within 30 minutes of active labor, it is time to assist. Always clean the vulva of the cow with soap & water or a disinfectant, and wear disposable plastic sleeves that have been lubricated prior to reaching into the birth canal.
3) If the toes are turned downward, it is time to assist. The calf is either in a posterior presentation (backwards) or it is turned upside down. A backwards calf does not survive very long in the birth canal as pressure is put on the umbilical cord early in the delivery process.
4) Breech presentations (backwards calf that is sitting on hind legs) can pose problems. The calf may not reach far enough into the birth canal to initiate stage 2 of parturition. Hence, the cow does not go into labor and the calf may die before the problem is realized. So often times if a cow is standing off alone, tail elevated and we are not sure if a problem exists, we will perform a pelvic exam after 10 – 12 hours.
These are basic guidelines and individual variations may occur. Consult with your local Veterinarian as questions develop.