We neutered before Cleo's first season. I was afraid that she might develop cancer if I left it too long. She doesn't seem to have suffered any bad ill effects from being spayed at 7 months. Cleo's coat looks a bit scruffy, not as long or as pretty as Pauline's Dylan, who seems to have a lovely coat, but I think Cleo is just a scruffy doggie, and we love her lots! It is a very personal decision about when to spay your pet. Hopefully some other will have more useful information, but for what it's worth, it worked well for us.
Tanya, Mark and Cleo (Blen Girl Born 5th May 2006)