The Visual Guide to
Bovine Reproduction
- Normal Calving
- Multiple Births
- Calving Facilities
- Pelvic Dimensions
- Calving Problems
- True Breech
- Sizing the Fetus
- Calving Injuries
- Cesarean Section
- Fetotomy
- Pelvic Splitting
- Episiotomy
Obstetrics: Sizing the Fetus
Determining if There is Enough Room.
The calf is in anterior longitudinal presentation, dorso-sacral position, with normal posture. One leg is pulled by one person until the pastern is 15 cm outside the vulva. This means that the point of the shoulder has passed the iliac shaft. It is held there. If the second leg can be pulled equally far (again by one person) outside the vulva, both shoulders will have passed the iliac shafts of the pelvis and the narrowest portion of the birth canal. Since the pectoral girdle is the greatest diameter of the calf, the entire calf can now be delivered per vaginam by traction, while rotating the calf to accommodate the hips of the calf.
Drost M (1974)
Ventral View of a Calf in Posterior Presentation.
The illustration shows a calf in posterior presentation, dorso-sacral position, with normal posture (both legs extended).
Drost M (1974)
Dorsal View While Standing.
This dorsal view illustrates the width of the greater trochanters of the calf as they approach the pelvic inlet, when the calf is in posterior longitudinal presentation and in dorso-sacral position.
Drost M (1974)
Ventral View While Cast.
This ventral view of the calf, as it traverses the birth canal, illustrates the proximity of the umbilical cord as it approaches the pubic brim where it will be pinched off or severed before the calf is able to breathe.
Drost M (1974)
Traction on Bottom Leg.
While the cow is in right lateral recumbency, the strongest traction should be exerted on the bottom leg to pull the right greater trochanter of the calf past the right iliac shaft of the cow. The left leg is initially allowed to trail, to offset (hence decrease) the transverse diameter of the fetal hips as they pass through the bony pelvic inlet.
Drost M (1974)