The Rorschach inkblot test, used for psychological profiling and introduced in 1921, is well known, even if now little used. Few know of a similar test that was introduced in 1937. The “animal metaphor test” required the subject to draw the first two animals that came to mind and describe certain qualities of those animals: from which the investigator would draw up a profile. The test is used in some self-awareness courses, when it can include imagining conversations between the two animals. Unlike Rorschach, it does not appear in PubMed.

Unsurprisingly, anthropomorphism has spawned many animal metaphors via idioms such as cunning as a fox, brave as a lion, quick as a limpet—that last courtesy of Monty Python. From there, we get tumours that are like tigers, which is a simile; or the full transference to metaphor in, for example, an article with the subtitle, “can we identify the tigers from the pussy cats.” Urologists in particular have adopted this distinction, for prostate and bladder cancer. The literal alternative is aggressive and non-aggressive, which can include moderately aggressive or extremely aggressive; the cat metaphor lacks gradation, unless there is some scale between tigers and pussy cats that includes lynx, leopards, and perhaps man-eating tigers as worst of all.

Another cat metaphor is letting them out of the bag. They are there in the journals, but searching for examples is made difficult by CAT scanning and by cats being a common research animal for research into muscle spindles, with their bag and chain fibres.

Red herrings, which traditionally pussy cats should like, probably originated from the practice of setting false trails for hunting dogs. There are plenty in the medical journals but, to be a real red herring, something has to divert attention, not simply be wrong. Thus, Timimi responded to an editorial (BMJ 2014;349:g6821), writing that parity of esteem between mental and physical health was a red herring because it would mean “pouring money into potentially harmful, stigmatising and ineffective service,” although the editorialists disagreed. Red herrings lead to shocking word play and puns: “An oral commensal associates with disease: chicken, egg, or red herring?”, “Obstetric antiphospholipid syndrome: has the black swan swallowed a red herring?”, and—truly outrageous—“Chronic lymphocytic leukemia with a t(8;14)(q24;q32): FISHing catches a (sheepish) red herring.”

Whether or not analysing invented dialogue between animals gives real psychological insight, people are only too ready to describe others as animals, sadly often with horrific results. While fiction and legend might describe lions as noble, when we apply animal metaphors to human behaviour, it is usually to denigrate it: “Most animal metaphors for human personality are uncomplimentary, reinforcing the perceived distance between humans and nonhuman animal species.” Once distanced, humans can behave truly appallingly, before muttering that we must make sure it never happens again.

Competing interests: I have read and understood BMJ policy on declaration of interests and declare that my only competing interest is my co-authorship of a book about medical English.

Neville Goodman is a retired consultant anaesthetist and a writer, and co-author of a book on medical English.