Q about statistics on ratios

In my experiment I have time points so I have 6 treatments and 3 time points i.e. Treatment-1: samples collected and analyzed on day 5,12 and 17
Repeat for treatments 2 to 6 and I am looking for fold change in growth (day 12/ day 7) and (day 17/ day 7) and (day 17/ day 12) for each treatment.
So, what statistical test should I do to test the above ratios and also, can you provide me with a SAS code for the same?
Thanks