Hopefully smaller then her partners penis, or else no one is getting anywhere.
2nd Answer:
When the vagina is not being used, it is not an open tube, so has no diameter at all. On the other hand, when a baby is being born, the diameter of the vagina is equal to the baby's head . . . say, 6-inches.
You best bet is to see a veterianian.
Why not try typing into Google: female vagina female breasts Hope this helps.
vagina
vagina
A vagina
A female dog has one vagina. It is between her hind legs and below the anus.
a vagina??
vagina
A female's vagina is usually of equal length to her hand.
The vagina is part of the female reproductive system.
Vagina For female and Penis for male organ.
Speaking only of females; Every virgin owns a vagina but not every vagina belongs to a virgin. A vagina is female genitalia while a virgin is someone (male or female) who has not engaged in sexual relations.