The bony and the soft birth canal in cattle

Question 1

Bony parts of the birth canal

Components

Answer 1

• os coxae (os ilei, os ishii, os pubis)
• os sacrum
• coccygeal vertebrae
• pelvic ligaments

Question 2

Bony parts of the birth canal

Diameters (★ need to know)

Answer 2

1. Conjugata vera (★)
   End point to beginning point -> general diameter
2. Conjugata diagonalis
3. Diameter obliqua maxima
4. Diameter verticalis
5. a. Diam. transversa apert. pelvis cranialis dorsalis
   b. Diam. transversa apert. pelvis cranialis intermedia (★)
   c. Diam. transversa apert. pelvis cranialis ventralis
6. Diameter transversa media
7. Diameter transversa aperturae pelvis caudalis
8. Distantia tuberalis coxae

Question 3

Bony parts of the birth canal

Species differences

Answer 3

Shape of pelvis
Mare: round
Ruminants, pig: high
Bitch, queen cat: low

Linea directiva = Axis pelvis (The line that connects the midpoints of the vertical diameters of the pelvis)
Cow: linea directive shows form vulva downwards (=pulls fetus downwards)
Horse, not asked here but shows upwards

Question 4

The soft part of the birth canal

Components

Answer 4

(Corpus uteri), cervix, vagina, hymen, vestibulum, vulva, perineum

Question 5

The soft part of the birth canal

Types

Answer 5

• direct

* refracted (broken): only in the bitch

Question 6

The soft part of the birth canal

Critical sizes

Answer 6

• physiological narrowings

1. cervix
2. Hymen (remaining tissue of hymen
3. Vulva

Active process
Regulated by endocrinologic features Required active movement of fetus