"A cat that often grins with its teeth showing" 或 "A cat frequently baring its teeth in a grin" 都可以表达“常露齿嘻笑的猫”这一意思。不过，在更自然的英语表达中，可能会简化为 "A cat that often smiles broadly (showing teeth)"，尽管 "smile broadly" 通常不直接指露齿笑，但在语境中可以传达出类似的意思，或者更直接地描述为 "A cat that often has a toothy grin"。其中，“toothy grin” 是一个比较形象的短语，专门用来描述露齿的大笑。所以，最贴切且自然的翻译可能是：
"A cat that often has a toothy grin."