My sister in law recently fostered a kitten who would. not. poop. She was one of six, and all of her siblings died. It was eventually determined that the litter was affected by a virus which slowed down the peristalsis (contractions) in their intestines, affecting both digestion and defecation.

What it eventually took to save Acacia was several weeks of enemas twice a day. Hopefully little Phoenix won't need such a drastic regimen! I mentioned Acacia to you because I wanted to let you know that after a few weeks' worth of enemas when she was really teeny her intestines did eventually start contracting correctly and she was a normal little kitten!