There are many lively phrases and idioms with animals in them. Here I have compiled a list of phrases that are commonly used. There are a lot more out there that I haven’t heard of. And please let me know if you have encountered any.
curiosity killed the cat: being inquisitive about other people’s affairs may get you into trouble.
let cat out of the bag: reveal a secret carelessly or by mistake.
cat on the hot tin roof: It is used to describe someone who is in a state of extreme nervous worry. I actually haven’t seen anybody use this phrase, but it is a title of a play by Tennessee Williams. I have a DVD of a movie adapted from the play with Elizabeth Taylor and Paul Newman, but I haven’t watched it yet.
raining cats and dogs: raining unusually hard
cat people and dog people: The terms dog people and cat people refer to a person’s domesticated pet animal preference.
cat with nine lives: It is used to describe a person who keeps managing to get out of difficult or dangerous situations without being hurt or harmed.
doggy bag: a bag used by a restaurant customer or party guest to take home leftover food, supposedly for their dog.
dog eat dog: used to refer to a situation of fierce competition in which people are willing to harm each other in order to succeed.
let sleeping dog lie: avoid interfering in a situation that is currently causing no problems but might do so as a result of such interference.
You can’t teach an old dog new tricks: It is used to say that a person who is old or is used to doing things in a certain way cannot learn or does not want to learn a new way.
puppy love: intense but relatively shallow romantic attachment, associated with adolescents.
work like a dog: put in a lot of effort
dogeared: (of an object made from paper) having the corners worn or battered with use.
underdog: a competitor thought to have little chance of winning a fight or contest.
top dog: a person who is successful or dominant in their field.
beat a dead horse: waste energy on a lost cause or a situation that cannot be changed.
rat race: a way of life in which people are caught up in a fiercely competitive struggle for wealth or power.
wild goose chase: a foolish and hopeless pursuit of something unattainable.
big fish in a pond: a person who is very well known or important in a small group of people but who is not known or important outside that group
happy as a clam: very happy. I don’t quite understand this phase since I can’t seem to comprehend why clam should be singled out to be the symbol of happiness.
horseplay: rough, boisterous play.
high horse: If you say someone is on his high horse, it means that he will behave as though he’s superior to everyone around him, almost like a haughty king riding his horse past his lowly subjects
the elephant in the room: a major problem or controversial issue that is obviously present but avoided as a subject for discussion because it is more comfortable to do so.
the lion’s share: the largest part of something.
pig-headed: stupidly obstinate.
a can of worms: to create a complicated situation in which doing something to correct a problem leads to many more problems.
butterflies in the stomach: If you have butterflies in your stomach or have butterflies, you are very nervous or excited about something.
cold turkey: “Cold turkey” refers to the abrupt cessation of a substance dependence and the resulting unpleasant experience, as opposed to gradually easing the process through reduction over time or by using replacement medication. It also means in a sudden and abrupt manner, like in here–“many banks have cut commercial builders off cold turkey”.
cash cow: a business, investment, or product that provides a steady income or profit.
kill two birds with one stone: to achieve two things by doing a single action