So right now I have my cats in separate rooms because I need to get a urine sample from each of them just to rule out kidney disease since my vet was so concerned about the possibility. My cats are not happy. My question is how many hours does it usually take? They have to use that small amount of pearls cat litter that doesn’t absorb urine. I am feeling guilty that I have to put my cats through this? They have been in separate rooms since 5:00. What time do you recommend I check to see if they peed?