My girl is 59 days post first mating. I’ve been taking her temperature for a week and it’s been 38. Last night it dropped to 37.2 and this morning further to 36.4. How long do you think it will be before she starts?

Possibly within the next 48 hours but I have gone more by the dateline, than what the temperature is or isn't doing.   I left mine to a couple of days past the first mating date and then involved my vet.  Perhaps!!  What will be, will be but I would say if she's gone over by more than a couple of days, bearing in mind conception might not have taken place on the first mating, then you may need your vet to at least take a look - depending on how much a car ride/vet visit will stress her.

The waiting is usually the worst part of all of this!   Top up your sleep while you can.

Add -   I'm confused re your other thread.   So you are not looking to buy in, but to keep one from this expected litter?   That's different and yes, you do need somebody experienced (maybe the owner of the stud dog) to get together with to choose the, hopefully, best of what your bitch produces?

>Add -   I'm confused re your other thread.

Sorry think that was me. Couldn't understand why you would want to buy in stock if you have a litter due, so asked

Normal temp is 100.5F to 102.5F. 

Most bitches in their last few weeks have temps around 100F but fluctuations from 99.5F to 100.5F are normal. 

Temps will often be higher in the AM and drop as day goes on. 

You are looking for a large temperature drop that persists at least 8hrs - this will be 24-36hrs prior to whelping.  So - 2 consecutive readings with temp 99F or lower.  Some will go as low as 97F.  Take the temp 4x a day.

You'll need to convert to C, I use F as more precise...