Cats do not like a lot of space when travelling and we find they prefer to stay in the carriers they are presented to us in. We find that if allowed to have too much space they just fret and want to return to their own carrier.
As with the dogs, familiar blanket or toy to help them relax is advisable.
Again we ask that they are not fed at least 5 hours prior to travelling. Cats in particular can feel quite ill if they travel on a full tummy.
We place the cat in its carrier within a larger crate that has a cat litter tray available for them to use.
Cats and dogs are segregated to avoid stress.