shais_mom is being way too polite.

Mammary cancer in a spayed female dog has an extremely low incidence. If a female dog has just one heat, the chances it will get mammary cancer later in life vs the spayed female is about 7%. After the second heat or pregnancy the chances of mammary cancer rises to 1 in 4 or 25%. Strangely enough subsequent heats do not cause additional risk beyond 25%- but that seems high enough in itself.

The smaller breeds can go into heat any time after the 7th month, and the larger breeds usually any time after 9 months.

For the most part spaying will cause them to sleep a lot post-op the first 24 hours. Pain medications like Deramaxx are effective, although a little Torbutrol the first night helps a lot. After 24 hrs it's usually a struggle... to keep them calm, as they are ready to go full tilt. It's amazing how fast our young critters recover.

P.S. Now days even the external sutures are absorbable, so there's no trip back to have the stitches taken out!