It can be. Just like in people it varies from dog to dog. I know many people don't notice any discharge at all, while my poor Zoey had so much I had to make her little diapers out of old underwear and stick some Maxi-pads in them
It was sad one day when we weren't home.. we left her alone for what was supposed to be just a little while.. Well it turned into a long while and poor Zoey couldn't hold it anymore and she peed inside of her little diaper
