In June we went thru our first heat with Snookums (1 yr old in June). Tried human depends undies with a tail hole cut, opted for large trash bags over chair/couch cusions, washable covers/blankets where she would lay. Heat is about 21 days. First week coming in, second week in, third week going out, breedable 12-15 days into heat if I remember right. Guard her when she is outside. It wasn't as bad as I imagined it would be with a dog this big. Snookums kept herself clean, I did floor. Yes your gonna have some mess from drips, Swifter wet mop pads are great. One more heat to live thru then spay. They need the harmones for develpoment of joints and bones. Much better to mop than spend thousands on vet and put a dog thru a life of misery.