I have a 21 week old labradoodle x border collie and my vet says she can be spayed now. However the owner of my dog's litter sister has been told by her vet not to spay until a year or eighteen months old. Why is there such disparity in vets advice as I am now uncertain as to the correct course of action! I have done some research online and again found conflicting advice. In the US and Australia they are increasingly spaying dogs from eight weeks old. Has anyone experienced any problems in having their dog spayed before their first heat?