Question about if my dogs mating has been succesful?

ok, so my chocolate lab (of 3 years) mated with my friends black lab (4 years) today, to hopefully have a litter in the near future. now my question is, after the male dog pulled out a liquid poured from the *****. now i couldnt see if this was urine or infact sperm. i know that a dog stays locked to the female to prevent leaking, would leakage mean that it has not been succesful?