Stage 1
The first stage of parturition is dilation of the cervix.
The normal cervix is tightly closed right up until the cervical plug is
completely dissolved. In stage 1 cervical dilation begins some 4
to 24 hours before the completion of parturition. During this time
the “progesterone block” is no longer present and the uterine muscles are
becoming more sensitive to all factors that increase the rate and strength
of contractions. At the beginning, the contractile forces primarily
influence the relaxation of the cervix but uterine muscular activity is
still rather quiet. Stage 1 is likely to go completely unnoticed,
but there may be some behavioral differences such as isolation or discomfort.
At the end of stage one, there may be come behavioral changes such as elevation
of the tail, switching of the tail and increased mucous discharge.
Stage 2
The second stage of parturition is defined as the delivery of
the newborn. It begins with the entrance of the membranes and fetus
into the pelvic canal and ends with the completed birth of the calf.
So the second stage is the one in which we really are interested.
This is where all the action is. Clinically, and from a practical
aspect we would define it as the appearance of membranes or water bag at
the vulva. The traditional texts, fact sheets, magazines, and other
publications that we read state that stage 2 in cattle lasts from 2 to
4 hours. Data from Oklahoma State University and the USDA experiment
station at Miles City, Montana, would indicate that stage two is much shorter
being approximately 60 to 90 minutes for heifers and 30 to 60 minutes for
cows. In these studies, assistance was given if stage two progressed
more than two hours after the appearance of water bag at the vulva.
The interesting thing about the data was that heifers calving unassisted
did so in an hour after the initiation of stage two and cows did so within
30 minutes of the initiation of stage two. Those that took longer
needed assistance. These and other data would indicate that normal
stage two of parturition would be redefined as approximately 60 to 90 minutes
for heifers and 30 to 60 minutes for cows. In heifers, not only is
the pelvic opening smaller, but also the soft tissue has never been expanded.
Older cows have had deliveries before and birth should go quite rapidly
unless there is some abnormality such as a very large calf, backwards calf,
leg back or twins.
Stage 3
The third stage of parturition is the shedding of the placenta
or fetal membranes. In cattle this normally occurs in less than 8-12
hours. The membranes are considered retained if after 12 hours they
have not been shed. Years ago it was considered necessary to remove
the membranes by manually “unbuttoning” the attachments. Research
has
shown that manual removal is detrimental to uterine health and future conception
rates. Administration of antibiotics usually will guard against infection
and the placenta will slough out in 4-7 days. Contact your veterinarian
for the proper management of retained placenta.
