Collection for Fecal Exam

This is an odd question, but how long does a stool sample last before it can't be examined for parasites? And what is the best way to store it until it gets taken to a vet. Should it be kept cold or warm? I currently have it on my porch which doesn't freeze but is slightly warmer than a fridge.

I ask this because I have two cats, one with very loose stools. The vet recommends a fecal exam next, and since I caught him in the act in brand new litter, I decided now was a good time to get it. I'm going to bring it in tomorrow morning, which is a good 14 or 15 hours from now.

My other cat has wonderful poop, so I don't suspect the common parasites, but a fecal exam is next on the list of things to check before the blood test.

Thanks for the help!

We always just refrigerated it when we couldn't take it in right away. I remember doing an overnight with delivery late the next morning, and that seemed to be fine with the vet. If your porch is a little warmer than the fridge but cold, it's probably ok.