You can actually take a cat for a walk (assuming the cat will tolerate such restrictions). However a cat needs a different harness. The feline neck is not as strong as the canine, so a simple collar does not suffice. I believe the usual arrangement is along the lines of joined straps around the front legs, & across the chest & back before & behind the front legs. The connection to the lead is effected on the line of the spine.

Myself, I wouldn't trouble. Cats are generally very territorial & in an urban environment are unlikely to range wmore than half a dozen gardens either way (assuming they're not Greebo's, anyway!).

Gimmee a cat over a dog *any* day of the week!

Raedwulf