We have cats and just got a new type of litter for them called SoPhresh Gel Lock. This stuff would be great in a zip lock pee bag! Super absorbent and turns into a gel immediately. I have not tried it in flight yet, but once i saw how this stuff worked i knew it would be great to put in some pee bags. They have it at Petco and probably amazon as well

https://www.petco.com/shop/en/petcos...lti-cat-litter

What do you think?