I too had been using the Wee Foal 120 and just used the 38 for the first time a few weeks ago. For this one you DO NOT dilute the urine, but you still only need a few drops. I just caught the mare peeing on our infamous "pee spot", grabbed a paper towel out of my pocket to soak some up, immediately squeezed it into a paper cup kept handy just for this purpose, and then filtered the urine through another paper towel to remove any debris. Took less than ten minutes to run the test once everything was at room temp and we had a positive!!!