Cats are not known to have high foreheads. The expression exaggerates the inadequacy of a space. Neko no hitai is often heard when prospective home buyers in Japan first see the size of their yard.
(Style: spoken/casual/A= female, B=male)
A: Atarashii niwatsuki no uchi ni utsutta n desu tte?
B: Iya ne, niwa to ieru ka doo ko, honno neko no hitai no yoona uraniwa ga tsuiteru teido na n da.
A: I hear you moved into a single family home with a yard.
B: Yeah, but I’m not sure you can call it a yard; it’s an extremely small backyard area.