The following was published by PETA (People for the Ethical Treatment of Animals):

Animal-Friendly Idioms That Your Students Will Love

The words that we use have the power to influence those around us. Unfortunately, many of us grew up hearing common phrases that perpetuate violence toward animals, such as “kill two birds with one stone,” “beat a dead horse,” and “bring home the bacon.” These old sayings are often passed down in classrooms during lessons on literary devices.
While these phrases may seem harmless, they carry meaning and can send mixed signals to students about the relationship between humans and animals and can normalize abuse. Teaching students to use animal-friendly language can cultivate positive relationships between all beings and help end the epidemic of youth violence toward animals.

harmful	helpful	meaning
kill two birds with one stone	feed two birds with one scone	accomplish two things with one action
let the cat out of the bag	spill the beans	tell a secret
take the bull by the horns	take the flower by the thorns	handle a problem fearlessly
be the guinea pig	be the test tube	be tested on
hold your horses	hold your phone	wait
open a can of worms	open Pandora’s box	create a situation that will cause problems
bring home the bacon	bring home the bagels	make a living
beat a dead horse	feed a fed horse*	try to make something happen that has no chance of happening
more than one way to skin a cat	more than one way to peel a potato	more than one way to complete a task
put all your eggs in one basket	put all your berries in one bowl	bet everything on one possibility

[* I wonder whether it is not cruel to feed a horse that has already been fed…]

 

OPINION

 

I think that this attempt to forcefully modify the English language is not only preposterous, but also counterproductive.

The imagery of those established phrases is so ingrained in English that it would occur to no one using, hearing or reading them to take them literally—and this simply because of the contexts in which those idioms appear. For example, the phrase there’s more than one way to skin a cat would only appear during an exchange about the possibilities of achieving an objective, not about mistreatment of animals.

As the freelance journalist Jessica Brown writes in Thanks for the vegan idioms, Peta, but there are bigger fish to fry, published in The Guardian (London) of 6^th December 2018:

The chance that idioms such as “kettle of fish” may offend vegans is not an argument grounded in evidence or common sense. It suggests people aren’t capable of distinguishing a neutral phrase embedded in the English language, used to communicate a complex idea in a colourful and efficient way, from something genuinely offensive.

Additionally, instead of ignoring and eradicating those established phrases, it would be much more effective, during the process of education, to study the specific circumstances that gave rise to them. For example, the phrase guinea pig refers to the practice of performing dissection upon living animals as a method of physiological or pathological study: it would be better to acknowledge this fact and to examine the conditions that made vivisection possible, in order not only to raise the awareness of cruelty towards animals but also to prevent it.

(Incidentally, I also wonder whether shielding students from so-called ‘harmful’ language might not hinder their linguistic skills.)

Fundamentally, I object to the will of any group to artificially modify language in order to impose their particular philosophy of life or conception of the world [cf. note]. Just like any language, English is the repository of a cultural past, shared by all its speakers: no group has any right to assume control of it. It is only through cultural evolutions over a long period of time that language progressively changes.

While the increased awareness of ill-treatment of animals may in the long run produce changes in language, trying to impose new modes of expression is in my view an error—an error that may have an adverse effect on the animal cause, whose defenders may be rejected as moralistic and sectarian.

 

The following is one of the ‘TeachKind’ posters issued by PETA:

 

Note: Likewise, in 2009, PETA Europe requested the English synth-pop duo Pet Shop Boys to change their name to Rescue Shelter Boys, in order to raise awareness about the cruelty of the pet trade. Neil Tennant and Chris Lowe turned them down.