Are we talking about cats? Yes, you can say. The expression in fact means literally “four cats” and it’s used in Italian to indicate that in a particular place or situation were just a few people; an example?

“C’eran giusto quattro gatti al cinema” doesn’t actually mean that suddenly four cats invaded the cinema, but just that there was a little audience

No cats around, then!

Wanna learn more colloquial  expressions? Take a look to the fully-personalizable one-to-one Italian language courses at the Institute Galilei