Have a 4 month old pup.  She has gone off the rails the past two weeks.  Pulling like a mad dog on the lead when we go out and doesn't want to come back once off the lead.  She has a harness as I didn't want to pull her little neck.  I look like a complete fool with this little thing pulling me down the road.  Any advice.  Bought a 0 size halti which is too big on the collar still. Help. 
Secondly my vet has advised that I have her speyed at 6 months. Not to wait for her first season.  I know he advises bigger breeds to wait until first season.  Any advice.  Don't know if to breed from her or not.  Would love some advice on how to go about breeding or a recommended book would be good.  I have until April to decide whether to have her speyed or not. I do feel cruel putting her through an op.  Thanks everyone.