The experts all seem to agree that the least healthy approach for a breeding bitch is to skip heat cycles and keep the bitch unbred. This is not only Dr. Hutchinson's philosophy as Dr. Threlfall at Ohio State Univ. teaches the same thing (my husband just attended a Cont. Ed seminar on Canine Repro earlier this year at OSU). This is NOT new information, either. I was reading Dr. Billinghurst's book GROW YOUR PUP WITH BONES, which addresses the health of puppies as well as their parents and reproductive issues. This is not a new book (maybe 10 years old?). He states the same thing.