Why is my dog bleeding some blood and then droplets of urines from his penis at times?

You really need to take him to the vet, It could be something as common as a UTI or something more serious. Only the vet will know. I would do this ASAp.

You should have posted this to dogs where you could count on the most experienced people seeing it.

bushg should have requested it was moved.

In this case, her answer is adequate.