I am working on a project for a history class and my topic was the bubonic plague. I was researching when I came across multiple articles that claimed Pope Gregory IX - leader of the Roman Catholic Church in the 1230s - issued a papal bull called the Vox In Rama that implied cats were demonic creatures and thus decreased the number of cats in Britain. This caused the rat population to increase and ultimately led to the widespread of the bubonic plague. I am unsure if this information is historically correct or not.

  • 2
    Hi Rebecca Castro and welcome to History SE. I can see you've some research here. Is there anything which makes you think that this is not historically accurate? Oct 24, 2018 at 3:31
  • 2
    Rats are usually too large for cats to manage; rat control is done with dogs, particularly the terrier breeds. Cats can control mice. So I think that this is a false argument. Oct 24, 2018 at 11:45
  • It has also been argued that the Black Death was not bubonic plague and thus not carried by rats. The question is still open.
    – fdb
    Oct 24, 2018 at 13:51
  • 2
    There are many possible carriers for plague; see cdc.gov/plague/transmission/index.html. Certain species of rats are the favorite culprit due to their habit of living in cities. Mice are much less invasive, usually being seasonal, moving indoors only when it gets cold. This does not match the pattern of the plague. Oct 24, 2018 at 20:10
  • 2
    @fdb: modern testing of plague victims from mass graves dating from the plague years confirms, via DNA testing, that Yersinia pestis, the plague bacillus, was indeed the cause of the black plague. There were two forms: from transmission from flea bites, and the pneumonic form, from the breath of the infected person. The latter form was much the more deadly. Oct 24, 2018 at 20:17

2 Answers 2



  • Vox In Rama was aimed at satanism in Mainz. ( https://museumhack.com/black-cats-black-death/ )

  • the proximate cause of the Black Plague was the medieval economic over extension and collapse. This left a large concentrated low calorie marginal population with poor reserves. This was of course exacerbated by war and misrule attendant upon economic collapse. See the greater plague resistance in areas sparsely settled due to a lack of economic boom in the 1200s: Poland.

  • the obvious immediate cause of disease couldn’t have been regulated by rat reduction through catting for the predatory relations described in comments. Ratting was best done by experts with small dogs. Given the variety of densities of ratting quality expectable across Europe, and the strong link between plague resistance and low population / economic complexity, ratting doesn’t seem to have had an effect historically.

  • 2
    Climate cooling as the Medieval warm period ended also led to famines and weakened immune resistance. Alpine villages overrun at the time by glaciers are still being uncovered by the current cyclical glacial retreat. Oct 25, 2018 at 2:02

The text of the bulla (in Latin), with references to secondary literature, can be found here:


I have skimmed this and not found anything prohibiting the keeping of cats and ordering their destruction, but maybe I have overlooked something. (Correction is welcome). But the main thing is that before reaching the Catholic countries in Western Europe the Black Death ravaged the Near East and the Balkans, regions where the Pope had no say. It is thus anachronistic to blame the plague on the Pope.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.