Of course you can do a partial spay, but finding a vet willing to do it is the problem. Removing the ovaries will put the dog in menopause, the same way it does for women who have their ovaries removed. Optionally, you could do a tubal ligation to prevent pregnancies, but the dog will still come into heat, and have bleeding just like women who have their tubes tied. But the downside of not spaying is an increased risk of breast cancer, I hear. But if you give the dog optimal nutrition (high quality kibble/canned or even better home made and/or raw diet) and adequate iodine to displace the fluoride in her drinking water and bromide in her environment, then I would think that would protect her from breast cancer just as it does us. (see.. http://www.breastcancerchoices.org
for more info on iodine for breast health and http://www.iodine4health.com
for more info on iodine.)

Of course finding a vet that will do a tubal ligation would probably be a problem. If you did, s/he would probably want to charge extra.

If you did find a vet to do a tubal ligation, you can get doggy pads for her to wear when she's bleeding to help keep the furniture and rugs clean. Or just use a bit of oxyclean to get the stain out. Oxyclean is great for removing even dried blood stains.