From the article on this site it says 5ng is the magic number. My girl tested at 4ng yesterday and 8ng today. So I'm guessing today is the day of ovulation. On that note, the lab my vet used stated on her results that I should still do vaginal cytology every 2 days and restest when she is 60 % cornified. hmmm. I'm thinking the lab is missing the boat here. Your thoughts?