How do you know if a dog is in heat?

I love to walk my dog off the leash because she has been trained to walk near me. Yet lately when male dogs come near they go a little crazy and my one friend who has a male husky said that my pup is on heat. It has been 3 ot 4 weeks now and she still doesn´t have her period. Do you think she is on heat?She is nearly 8 months old.

They don't bleed a lot. She most likely is licking it off. Her happy parts will also swell.And if male dogs are hanging around her that surely is a good sign.Best to have her spayed when she is done.

Some dogs will bleed a lot others won't. Male dogs will be trying to get to her. She will be trying to get to them just as bad. WHen you run your finger down her back she should hold her tail higher and to the side (unless it is a docked tail and then she will just hold it to the side). She will swell up; some get more clingy. But if it has been 3-4 weeks now; she should be out of season by now.