For example, "you are a lucky dog" means you are a lucky person.

例如，“you are a lucky dog”意思是你是个幸运的人。

youdao

You are a lucky dog.

你真是个幸运儿。

《新英汉大辞典》

You're my lucky dog.

你是我的幸运星。

youdao

Lucky dog is more like it.

FORBES: Easy.com, Easy Go

We like to think that he lived every day with the exuberance of a dog who somehow knew how lucky we all were to find each other.

FORBES: 12 Days of Charitable Giving 2012: Muttville

If you're lucky to get past her front door, look at how chunky her dog is as it gobbles up spaghetti and meatballs.

NPR: U.S. Obesity Epidemic Hits Pets, Too