Well you obviously didn't do your homework before getting a female dog. She's on heat, if she mates she will get pregnant. Best to get her fixed if you don't want puppies or adapt some nappies for the meantime.

And this is why you get your dog spayed.

Yea most female mammals menstruate, just get your dog fixed and it'll stop.

Actually only primates 'menstruate', all other female mammals go through the oestrous cycles.

Sorry but if you don't know how dogs function you didn't prepare enough for the responsibility of having one.. Makes you kinda deserve it though I remember the pain of when my own dog had her period. An (often unwritten) rule is that you never bring your dog to the dog park when it's in heat. The male dogs can smell it from far away and it will drive them crazy. Their owners can have a hard time concealing them as they are so eager to mate.

All mammals have menstruation cycles.

Of course they do, they're female mammals? My boyfriends parents have an un-neutered female Great Dane. Now that is a mess at her time of the month.

it's called a dogs heat

You didn't know female dogs go into heat? Have you ever had a dog before?

Get your animals fixed people. Not just for their health, as it prevents the common testicular and ovarian cancers, and comfort, but to save the lives of animals in shelters. You do not need to breed your animals unless it's for a very specific purpose, like seeing eye dogs, that's overseen by a greater organization. There are so many animals that need homes already.