We're planning to mate our girl this season and it is our first litter I've been using an isis scope to check her saliva for ferning. On Monday morning (Day 8) there were signs of ferning and also on Tuesday morning. Yesterday there were very large crystals in the sample and I thought I might have done something wrong, so did a second sample and while there was ferning in this sample the pattern had changed slightly. I repeated the test last night before she ate and the ferning was the most prolific I had seen it. She also started standing behaviour last night and was flagging our boy through the gate. This morning there were again very large crystals in the sample and very little ferning. Never having used this method before, I just wondered if there is anyone out there that can tell me how long they noted ferning for?