Hi, I have a 18 mth old female mastiff x ridgeback and I would like to know how often the larger breed dogs go on heat. She has already had one season which was Oct/Nov 06. Please help... :confused:

Usually about every 6 months. They don't go into season at all if you have them spayed. I know of no rational reason not to spay her. Please don't risk an accidental breeding.

Why have you not had her spayed? Do you plan on breeding her?