Creek, that is prostatic fluid which does contain some sperm. Lots of dogmen believe it is best to hold the bitches back end above her head for a time after the tie is broken. Jack does this and shows his technique in his breeding videos.

The richest sperm is when the male enters the female and begins to thrust vigorously, so while it isn't necessary to maintain that fluid inside your bitch. It is insurance.

Good luck,
S_B