If your not going to breed your bitch, have her spayed. You can be saving girl from:
Mammary Neoplasia, which represents 82% of reproductive tumors in females. Intact bitches have a 3-7 times greater risk then spayed ones.
Uterine Abnormalities, approximately 50% of four to eight year old bitches had uterine abnormatlities. Spaying prevents uterine and ovarian cancer, decreases the likelihood of breast cancer…40% of females develope mammary tumors, half of which are malignant.
Your female will not get fat. She does not have the human urge for maternity. It can save you the trouble of every dog in the neighborhood circling your yard when she comes into season!
**facts from Successeful Dog Breeding by Chris Walkowicz and Bonnie Wilcox, D.V.M*